Category: Oil Burner

Troubleshooting Oil Burners


Individuals involved in the installing and repairing of oil burners should be aware of a number of different indicators of malfunctions in the equipment, their probable causes, and some suggested remedies.

The average individual is most aware of malfunctions that warn the senses through excessive noise, smoke, or odor. These are external warning signals that require immediate investigation. Their nature is such that tracing the probable cause of the malfunction is made easier.

Excessive noise (pulsation, thumping, rumbling, etc.) in the heating unit is generally caused by a problem with the oil burner nozzle. It can usually be corrected by any one of the following methods:

• Replace the nozzle with one having a wider spray angle.
• Replace the nozzle with one having the next size smaller opening.
• Install a delayed-opening solenoid on the nozzle line (this reduces pulsation).

Sometimes a noisy fire is caused by cold oil originating from outside storage tanks. This noise may be greatly reduced or eliminated by pumping the fuel oil under 120 to 125 psi through the next size smaller nozzle.

Excessive smoke has a number of possible causes, including the

• The air-handling parts of the oil burner may be too dirty to operate efficiently.
• The combustion chamber or burner tube may be damaged by burn-through or loose materials.
• The oil burner nozzle may be the wrong size.

The dirty air-handling parts (e.g., the fan blades, air intake, and air vanes in the combustion head) can be made to operate more efficiently by a thorough cleaning. If the excessive smoke is caused by the oil burner nozzle, this can be corrected by replacing the nozzle with one that is a size smaller or one having the next narrower spray angle. A damaged combustion chamber is a more difficult problem to correct than the other two. In any event, all leakage through the walls must be eliminated before the oil burner can be expected to operate efficiently.

Excessive odors can be caused by flue obstructions or poor chimney draft. If the draft over the fire is lower than 0.02 to 0.04, it is usually an indication that the problem lies with the flue or chimney draft. The cause is usually an obstruction in the flue or poor chimney draft. Other causes of excessive odor include the following:

• Delayed ignition
• Too much air through the burner

Delayed ignition is commonly traced to a problem with the electrodes. This condition can result from a variety of causes, including the following:

• Improper electrode setting
• Insulator cracks
• A coating of soot or oil on the electrode
• Incorrect pump pressure setting
• Incorrect spray pattern in the nozzle
• Clogged nozzle
• Air shutter open too far

Table 1-6 lists a number of recommended electrode settings that should eliminate delayed ignition if the electrode setting is the cause of the problem. The type of nozzle spray pattern can also result in delayed ignition. This is particularly true when using a hollow spray pattern in oil burners firing 2.00 gph and above. It can be corrected by replacing the nozzle with one having a solid spray pattern.

table 1 6 Troubleshooting Oil Burners

Table 1-7 lists a variety of problems encountered with oil burners, many of which are of an internal nature and require a great degree of experience and training to correct.

Table 1-7 Oil Burner Troubleshooting

Symptom and Possible Cause Possible Remedy
No heat—circulator (pump) off and burner running.
(a) Defective circulator. (a) Replace circulator.
(b) Defective thermostat. (b) Replace thermostat.
(c) Defective relay. (c) Replace relay.
(d) Defective aquastat. (d) Replace aquastat.
(e) Incorrect aquastat setting. (e) Reset aquastat.
(f) Loose or disconnected wiring. (f) Tighten or reconnect wiring.
(g) Defective zone valve. (g) Replace zone valve.
No heat—both circulator (pump) and burner running.
(a) Defective or loose circulator coupling. (a) Repair or replace.
(b) Broken circulator impeller. (b) Repair or replace circulator.
(c) Air trapped in lines. (c) Locate point of entry and repair; purge air from lines.
(d) Loose or disconnected wiring. (d) Tighten or reconnect wiring.
(e) Defective zone valve. (e) Replace zone valve.
(f) Frozen flow valve. (f) Repair or replace flow valve.
No oil flow at nozzle.
(a) Oil level below intake line in oil storage tank. (a) Fill tank with oil.
(b) Clogged strainer. (b) Remove and clean strainer.
(c) Clogged filter. (c) Replace filter element.
(d) Clogged nozzle. (d) Replace nozzle.
(e) Air leak in intake line. (e) Tighten all fittings in intake line; tighten unused intake port plug; check filter cover and gasket.
(f) Restricted intake line (high vacuum reading). (f) Replace any kinked tubing and check valves in intake line.
(g) Air-bound two-pipe system. (g) Check for and insert bypass plug. Make sure return line is
below oil level in tank.
(h) Air-bound single-pipe system. (h) Loosen gauge port plug or easyflow valve and bleed oil for
15 seconds after foam is gone in bleed hose. Check intake line fittings for tightness and tighten if necessary. Check all pump plugs for tightness and tighten if necessary.
(i) Slipping or broken coupling. (i) Tighten or replace coupling.
(j) Rotation of motor and fuel unit is not the same as indicated by arrow on pad at top of unit. (j) Install fuel unit with correct rotation.
(k) Frozen pump shaft. (k) Check for water and dirt in tank and correct as necessary;
return defective pump to manufacturer or service center for repair or to be replaced.
Noisy operation.
(a) Bad coupling alignment at fuel unit. (a) Loosen fuel unit mounting screws slightly and shift fuel unit in different positions until noise is eliminated. Retighten mounting screws.
(b) Air in inlet line. (b) Check all connections for damage. Replace as necessary. Use only good flare fittings.
(c) Tank hum on two-pipe system and inside tank. (c) Install return-line hum eliminator in return line.
Pulsating pressure.
(a) Partially clogged strainer. (a) Remove and clean strainer.
(b) Partially clogged filter. (b) Replace filter element.
(c) Air leak in intake line. (c) Tighten all fittings; replace damaged fittings and/or damaged intake line.
(d) Air leaking around strainer cover. (d) Check for loose cover screws and tighten securely. Check for damaged cover gasket and replace if necessary.
Low oil pressure.
(a) Defective gauge. (a) Replace defective gauge.
(b) Burner nozzle capacity is greater than fuel unit capacity. (b) Replace fuel pump with one of correct capacity.
Improper nozzle cutoff.
(a) Trapped air causing fuel pump operating problem. (a) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drops from normal operating pressure and stabilizes, the fuel pump is running and the problem is with trapped air. Correct as necessary.
(b) Defective fuel pump. (b) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drop is 0 psi, fuel pump is defective and should be replaced.
(c) Filter leaks. (c) Check face of cover and gasket for damage and repair or replace as necessary.
(d) Loose strainer cover. (d) Tighten strainer cover screws.
(e) Air pocket between cutoff valve and nozzle. (e) Run burner by stopping and starting unit until smoke and afterfire disappear.
(f) Partially clogged nozzle strainer. (f) Clean strainer or change nozzle.
(g) Leak in nozzle adapter. (g) Change nozzle and adapter.
Oil leak—oil leaking inside burner.
(a) Seal leaking. (a) Replace seal or pump.
(b) Blown seal in a single-pipe system. (b) Check to see if bypass plug has been left in fuel pump. Replace pump.
(c) Blown seal in a two-pipe system. (c) Check for kinked tubing or other obstructions in return line. Replace pump.
(d) Cracked nozzle adapter. (d) Replace nozzle adapter.
(e) Defective pump piston. (e) Replace pump.
(f) Loose fitting. (f) Tighten or replace fitting.
(g) Loose fuel unit cover. (g) Tighten cover screws.
(h) Loose plugs or fittings. (h) Dope with good-quality thread sealer; retighten plugs or fittings.
(i) Leak at pressure adjustment screw or nozzle plug caused by damaged washer or O-ring. (i) Replace washer or O-ring as necessary.
(j) Damaged gasket. (j) Replace gasket.
Oil leak—oil leaking on outside of burner.
(a) Loose fittings. (a) Tighten fittings.
(b) Defective fittings. (b) Replace fittings.
(c) Damaged gasket. (c) Replace gasket.
Burner running—no oil pumping into combustion chamber and no fire in chamber.
(a) No oil in storage tank. (a) Fill storage tank.
(b) Clogged fuel pump. (b) Repair or replace fuel pump.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Clogged nozzle. (d) Clean or replace nozzle.
(e) Damaged or defective nozzle. (e) Replace nozzle.
(f) Clogged filter. (f) Clean or replace.
(g) Obstructed oil line. (g) Remove obstruction or replace fuel line.
(h) Closed oil valve. (h) Repair or replace oil valve.
(i) Loose or defective oil pump coupling. (i) Tighten coupling or replace oil pump.
(j) Defective oil valve. (j) Replace valve.
(k) Lost prime. (k) Reestablish prime or replace pump.
Burner running—oil pumping into combustion chamber but no fire in chamber.
(a) Chamber obstructed. (a) Locate and remove obstruction.
(b) Too much air. (b) Adjust to proper level.
(c) Water contaminating the oil. (c) Locate point of contamination and repair; drain and replace oil.
(d) Defective or weak ignition transformer. (d) Replace ignition transformer.
(e) Dirty electrodes. (e) Clean electrodes.
(f) Cracked or broken electrodes. (f) Replace electrodes.
(g) Loose wires. (g) Tighten connection or replace wires.
(h) End cone obstruction. (h) Repair.
Smoky fire.
(a) Improper pump pressure. (a) Set proper pump pressure or replace defective pump.
(b) Incorrect nozzle. (b) Replace nozzle.
(c) Distorted and burnt end cone. (c) Replace.
(d)Water contaminating the oil. (d) Locate point of contamination and repair; drain and replace oil.
(e) Dirty boiler. (e) Clean boiler.
(f) Dirty fan. (f) Clean fan
(g) Defective combustion chamber. (g) Replace.
Burner fails to restart after resetting safety relay.
(a) Power off. (a) Restore electricity to burner.
(b) Defective burner motor. (b) Replace burner motor or burner.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Defective safety relay. (d) Replace safety relay.
(e) Defective on-off switch. (e) Replace switch.
(f) Tripped circuit breaker. (f) Reset circuit breaker; call electrician if problem continues.
(g) Blown fuse. (g) Replace fuse; call electrician if problem continues.
(h) Loose or disconnected wiring. (h) Reconnect wires and tighten wiring connections.
Flame pattern not centered.
(a) Improperly positioned burner. (a) Reposition burner.
(b) Contaminated fuel. (b) Locate source of contamination and repair; drain and replace fuel.
(c) Obstruction in combustion chamber. (c) Locate and remove obstruction.
Water leaking from boiler pressure relief valve with pressure under 30 psi.
(a) Defective pressure relief valve. (a) Replace pressure relief valve.
Water leaking from boiler pressure relief valve with pressure at 30 psi or greater.
(a) Defective feed valve. (a) Replace valve.
(b) Holes or cracks in coils. (b) Replace coils.
(c) Expansion tank full. (c) Correct as necessary.
(d)Water temperature above 210°F . (d) Reduce water temperature; replace valve.

Combustion Testing and Adjustments


The following instruments are recommended for combustion testing and adjustments:

• Draft gauge
• Smoke tester
• Carbon dioxide tester
• 200/1000°F stack thermometer
• 0/150-psig pressure gauge
• 0/30-inch mercury vacuum gauge

Smoky combustion indicates poor burner performance. The amount of smoke in the flue gas can be measured with a smoke tester (see Figure 1-40). The tube of the smoke tester is inserted through a 3?8-inch hole drilled in the flue pipe, and the test is run as shown in Figure 1-41. Any smoke in the air drawn into the smoke tester will register on a filter paper inserted in the device. The results are interpreted according to the smoke scale in Table 1-5.

smoke tester Combustion Testing and Adjustments

smoke tester in use Combustion Testing and Adjustments

One of the most common causes of smoky combustion is soot formation on the heating surfaces. This is easily corrected by cleaning. Other possible causes of smoky combustion include the following:

• Insufficient draft
• Poor fuel supply
• Fuel pump malfunctioning
• Defective firebox
• Incorrectly adjusted draft regulator
• Defective oil-burner nozzle
• Wrong size oil-burner nozzle
• Improper fan delivery
• Excessive air leaks in boiler or furnace
• Unsuitable fuel-air ratio

table 1 5 Combustion Testing and Adjustments

Net stack temperatures in excess of 700°F for conversion units and 500°F for packaged units are considered abnormally high. The net stack temperature is the difference between the temperature of the flue gases inside the pipe and the room air temperature outside. For example, if the flue gas temperature is 600°F and the room temperature is 75°F , then the net stack temperature is 525°F (600°F – 75°F = 525°F).

stack gas temperature test Combustion Testing and Adjustments

A 200/1000°F stack thermometer is used to measure the flue gas temperature. The thermometer stem is inserted through a hole drilled in the flue pipe (see Figure 1-42). A high stack temperature may be caused by any of the following:

• Undersized furnace
• Defective combustion chamber
• Incorrectly sized combustion chamber
• Lack of sufficient baffling
• Dirty heating surfaces
• Excessive draft
• Boiler or furnace overfired
• Unit unsuited to automatic firing
• Draft regulator improperly adjusted

When the carbon dioxide (CO2) content of the flue gas is too low (less than 8 percent), heat is lost up the chimney and the unit operates inefficiently. This condition is usually caused by one of the following:

• Underfiring the combustion chamber
• Burner nozzle is too small
• Air leakage into the furnace or boiler

When the carbon dioxide content is too high, the furnace operation is generally characterized by excess smoke and/or pulsations and other noises. A high carbon dioxide content is usually caused by insufficient draft or an overfired burner.

co2 indicator Combustion Testing and Adjustments

The carbon dioxide reading is also taken through a hole drilled in the flue pipe with a CO2 indicator (see Figure 1-43). The CO2 indicator is used as shown in Figure 1-44. The results are indicated by a test liquid on a scale calibrated in %CO2.

co2 test Combustion Testing and Adjustments

A correct draft is essential for efficient burner operation. Insufficient draft can make it almost impossible to adjust the oil burner for its highest efficiency. Excessive draft can reduce the percentage of carbon dioxide in the flue gases and increase the stack temperature.

For the most efficient operating characteristics, the overfire draft generally should be not less than 0.02 inch wg. Smoke and odor often occur when the overfire draft falls below 0.02 inch wg.

It may be necessary to adjust the barometric draft regulator to obtain the correct overfire draft. If it is not possible to adjust the overfire draft for a –0.01 to 0.02 inch wg, install a mechanical draft inducer between the chimney and the barometric draft regulator.

The primary air band should be adjusted to a 0+ smoke or until a hard clean flame is visible. A clean flame is preferred to one with high carbon dioxide. Adjust the overfire draft for a –0.01 to a –0.02 inch wg. An excessive overfire draft condition will cause high stack temperature and inefficient operation. A too low or positive draft over the fire will usually cause the flue gases and fumes to seep into the space upon startup or shutdown.

The flue pipe draft in most residential oil burners is between 0.04 and 0.06 inches of water. This is sufficient to maintain a draft of 0.02 inches in the firebox.

MZF draft gauge Combustion Testing and Adjustments

The furnace or boiler draft is measured with a draft gauge as shown in Figure 1-45. A hole is drilled in either the fire door (overfire draft measurement) or flue pipe (flue pipe draft measurement), and the unit is run for approximately 5 minutes. The draft tube is then inserted into the test hole, and the gauge is read (see Figure 1-46).

overfire test Combustion Testing and Adjustments

Starting an Oil Burner


Oil burner manufacturers provide detailed starting and operating instructions for their burners in their user manuals. These instructions should be carefully followed when attempting to start an oil burner. If there is no available user manual, contact a local representative of the manufacturer or contact the manufacturer directly for a copy.

The procedure for starting an oil burner may be summarized as follows:

1. Open all warm-air registers.
2. Check to be sure all return air grilles are unobstructed.
3. Open the valve on the oil supply line.
4. Reset the burner primary relay.
5. Set the thermostat above the room temperature.
6. Turn on the electric supply to the unit by setting the main
electrical switch to the on position.
7. Change the room thermostat setting to the desired temperature.

The oil burner should start after the electric power has been
switched on (step 6). There is no pilot to light as is the case with
gas-fired appliances. The spark for ignition is provided automatically
on demand from the room thermostat.

Allow the burner to operate at least 10 minutes before making any final adjustments. Whenever possible, use instruments to adjust the fire.

Installing an Oil Burner


Under most circumstances, oil burners and oil-fired units should be installed in rooms that provide adequate clearance from the combustible material. The only exception to this rule is when specific instructions are given otherwise. In this case, the manufacturer provides or specifies a suitable combustion chamber (stainless steel, firebrick, etc.).

All local codes and ordinances take precedence over the oil burner manufacturer’s installation and operation manuals.Where local codes do not exist, install the oil burner in accordance with the most recent instructions and regulations of the National Fire Protection Association and the provisions of the National Electrical Code (ANSI/NFPA 70-199 or latest edition).

Only certified HVAC technicians or those with equivalent experience should attempt to install an oil burner.

Some sort of manual shutoff control should be provided for the oil burner in order to stop the flow of oil to the burner when the air supply is interrupted. This must be placed at a safe distance from the unit and in a convenient location. These manual shutoff valves generally consist of either a switch in the burner supply circuit (for electrically driven units) or a shutoff valve on the oil supply line.

Primary safety controls (automatic shutoff devices) must be provided for all oil burners and oil-fired units that operate automatically without the need of an attendant on duty—in other words, those types of equipment found where a stationary engineer would not be employed (i.e., noncommercial and nonindustrial locations).

One problem encountered when converting solid-fuel heating equipment to oil use is the accumulation of potentially dangerous vapors in the ashpit of the unit. This can be avoided by removing the ash door or by providing bottom ventilation to the unit. This precaution is unnecessary if the ashpit also serves as a part of the combustion chamber.

Never install or permit the installation of an oil burner until the boiler or furnace has first been inspected and found to be in good condition. The flue gas passages must be tight and free of any leaks.

All oil burners listed by Underwriters Laboratories, Inc., and Underwriters Laboratories of Canada meet the safety requirements detailed in the various booklets of the National Fire Protection Association.

Primary Safety Control Service


The cadmium detection cell is the most effective type of primary safety control used on oil burners. Malfunctions cause primary safety control to build up electrical resistance across the cell until the burner is automatically shut off. As soon as the burner shuts off, a reset button pops up on the burner. The button must be reset (pushed down) to restart the burner.

If the burner does not restart when the reset button is pushed down, do NOT keep resetting the button. Doing so will flood the firebox with oil. If ignition does not take place, the flooded firebox could result in a fire or an explosion.

The primary safety control can be tested by removing the motor lead from the burner and allowing the ignition circuit to be energized. Figures 1-38 and 1-39 illustrate two typical wiring diagrams for primary safety controls.

ignition wiring Primary Safety Control Service

intermittent ignition Primary Safety Control Service

Oil Burner Air System


The air system for the average oil burner is generally composed of the air shutter draft tube, the turbulator, and the fan. The draft tube and turbulator have already been shown

The fan construction consists of a (squirrel cage) series of vanes or blades mounted on the rim of a wheel. These vanes are slanted forward in such a manner as to provide the maximum discharge of air. Figure 1-36 shows the construction of a fan and flexible coupling.

coupling Oil Burner Air System

The operating principles of the air system are fairly simple. The fan draws air into the fan housing and forces this air through the draft tube and turbulator and into the combustion chamber. The amount of incoming air can be regulated by adjusting the air shutter. As the air is forced through these vanes, it is given a swirling motion just before it strikes the oil spray. This motion provides a more thorough mixture of the oil and air, resulting in better combustion.

The shape of the turbulator varies in different models, but the purpose is the same: to thoroughly mix the air and oil spray. Figure 1-37 shows a double turbulator consisting of an air impeller and nose piece.

draft tube1 Oil Burner Air System

Oil Burner Electrodes


The electrodes must be frequently checked and adjusted to ensure proper and efficient ignition of the fuel oil. Broken or malfunctioning electrodes can result in smoke leaking out into the rooms of the structure. This problem, called a puffback, is not an uncommon one in oil-fired appliances (see sidebar).

A puffback, or the leaking of sooty smoke from the combustion chamber of an oil furnace or boiler, is caused by the accumulation of fuel oil in the combustion chamber of the furnace or boiler after an ignition failure. When the oil burner is successfully restarted, the accumulated fuel oil burns too rapidly for the exhaust system to carry away the smoke. The excess smoke is forced out into the rooms through the seams in the furnace or boiler combustion chamber walls. Damaged electrodes are not the only cause of puffback. Other causes include the following:

• Ignition transformer failure
• Contaminated or eroded oil burner nozzle
• Fuel pump malfunction
• Clogged oil filter
• Clogged burner air intake
• Damaged combustion chamber linings

Oil Burner Nozzles


An oil burner nozzle is a device designed to deliver a fixed amount of fuel to the combustion chamber in a uniform spray pattern and spray angle best suited to the requirements of a specific burner. The oil burner nozzle atomizes the fuel oil (i.e., breaks it down into extremely small droplets) so that the vaporization necessary for combustion can be accomplished more quickly.

The components in a typical nozzle (see Figure 1-30) include the following:

1. Orifice.
2. Swirl chamber.
3. Orifice disc.
4. Body.
5. Tangential slots.
6. Distributor.
7. Retainer.
8. Filter.

oil burner nozzle Oil Burner Nozzles

Fuel oil is supplied under pressure (100 psi) to the nozzle, where it is converted to velocity energy in the swirl chamber by directing it through a set of tangential slots. The centrifugal force caused within the swirl chamber drives the fuel oil against the chamber walls, producing a core of air in the center. The latter effect moves the oil out through the orifice at the tip of the nozzle in a coneshaped pattern.

The following are the two basic spray cone patterns:

1. The hollow cone.
2. The solid cone.

Each has certain advantages depending on its use.

The hollow cone pattern (see Figure 1-31) is recommended for use in smaller burners (those firing 1.00 gph and under). As shown in Figure 1-31, they are characterized by a concentration of fuel oil droplets all around the outer edge of the spray. There is little or no distribution of droplets in the center of the cone. The principal advantage of the hollow cone patterns is a more stable spray pattern and angle under adverse conditions than solid cone patterns operating under the same conditions and at the same flow rate.

hollow spray Oil Burner Nozzles

The solid cone pattern, illustrated in Figure 1-32, is characterized by a uniform or near-uniform distribution of fuel oil droplets throughout the cone pattern. Nozzles producing this cone pattern are particularly recommended for smoother ignition in oil burners firing above 2.00 or 3.00 gph. They are also recommended where long fires are required or where the air pattern or the oil burner is heavy in the center.

solid spray Oil Burner Nozzles

A combination cone pattern that is neither a true cone nor a true hollow cone can be used in oil burners firing between 0.40 gph and 8.00 gph.

spray angles Oil Burner Nozzles

Oil burner nozzles are also selected on the basis of the spray angle they produce (see Figure 1-33). The spray angle refers to the angle of the spray cone, and this angle will generally range from 30° to 90°. The angle selected will depend on the requirement of the burner air pattern and combustion chamber. For example, 70° to 90° spray angles are recommended for round or square combustion chambers (see Figure 1-34), and 30° to 60° spray angles are recommended for long, narrow chambers (see Figure 1-35). Recommended combustion chamber dimensions and spray angles for nozzles are given in Table 1-4.

spray angles chamber Oil Burner Nozzles

spray angles chamber 2 Oil Burner Nozzles

table 1 4 Oil Burner Nozzles

Troubleshooting Fuel Pumps


The troubleshooting list in Table 1-3 contains the most common operating problems associated with fuel pumps and fuel units. Each problem is given in the form of a symptom, the possible cause, and a suggested remedy. The purpose of this list is to provide the operator with a quick reference to the cause and correction of a specific problem.

Table 1-3 Troubleshooting Fuel Pumps

Symptom and Possible Cause Possible Remedy
No oil flow to nozzle.
(a) Clogged strainer or filter. (a) Remove and clean strainer; repack filter element.
(b) Air binding in two-pipe system. (b) Check and insert bypass plug.
(c) Frozen pump shaft. (c) Remove pump and return it to the manufacturer for repair or replacement.
Oil leak.
(a) Loose plugs or fittings. (a) Dope with good-quality thread sealer.
(b) Leak at pressure-adjusting end cap nut. (b) Fiber washer may have been left out after adjustment of valve spring; replace washer.
(c) Blown seal. (c) Replace fuel unit.
(d) Seal leaking. (d) Replace fuel unit.
Noisy operation.
(a) Air inlet line. (a) Tighten all connections and fittings in the intake line and unused intake port plugs
(b) Bad coupling alignment. (b) Loosen mounting screws and shift fuel pump to a position where noise is eliminated. Retighten mounting screws.
(c) Pump noise. (c) Work in gears by continued running or replace.
Pulsating pressure.
(a) Air leak in intake line. (a) Tighten all fittings and valve packing in intake line.
(b) Air leaking around strainer cover. (b) Tighten strainer cover screws.
(c) Partially clogged strainer. (c) Remove and clean strainer.
(d) Partially clogged filter. (d) Replace filter element.
Low oil pressure.
(a) Nozzle capacity is greater than fuel pump capacity. (a) Replace fuel pump with one of correct capacity.
(b) Defective gauge. (b) Check against another and replace if necessary.
Improper nozzle cutoff.
(a) Filter leaks. (a) Check face of filter cover and gasket for damage.
(b) Partially clogged nozzle strainer. (b) Clean strainer or change nozzle.
(c) Air leak in intake line. (c) Tighten intake fittings and packing nut on shutoff valve; tighten unused intake port plug.
(d) Strainer cover loose. (d) Tighten screws.
(e) Air pockets between cutoff valve and nozzle. (e) Start and stop burner until smoke and afterfire disappear.

Adjusting Fuel Pump Pressure


The oil-pressure regulator on the fuel pump is generally factory-set to give nozzle oil pressures of 100 psig. The firing rate is indicated on the nameplate and can be obtained with standard nozzles by adjusting the pump pressures as follows:

1. Turn the adjusting screw clockwise to increase pressure.
2. Turn the adjusting screw counterclockwise to decrease pressure.
3. Never exceed the pressures indicated in Table 1-2.

table 1 2 Adjusting Fuel Pump Pressure