944 Fuel Pump Relay Location: Find It Fast

On an early Porsche 944 (before the 1985.5 update), the fuel pump relay is on the fuse and relay panel under the driver-side dash on a left-hand-drive car. On 1985.5 and newer 944s, the part usually called the DME relay is in the central fuse and relay panel at the rear left of the engine compartment, close to the windshield and A-pillar. That is the short answer most owners need when the engine cranks but will not start. The model-year change matters because the car uses two different panel layouts, and the name on a parts listing may say "fuel pump relay," "DME relay," or both. On later cars, one relay supplies power to the engine control unit and the fuel pump, so either half failing can stop the engine from starting.

This guide covers how to identify your car, find the correct relay socket, recognize common failure signs, check the fuse and power supply, and decide whether the relay or the pump itself is at fault. The instructions are written for U.S. left-hand-drive cars. If you have an imported or modified car, confirm the panel layout with the owner's manual or a wiring diagram for your VIN before ordering parts.

1. Start With the Year and the Panel

Many online answers are confusing because they describe only one generation of the 944. Use this breakdown first:

1. Early 944s, before 1985.5: Look under the dash on the driver's side for the fuse and relay panel. The part is commonly called the fuel pump relay. The auxiliary fuse panel carries the fuel pump fuse at fuse #2.
2. 1985.5 and newer 944s: Open the hood and look at the rear left side of the engine compartment, near the windshield and A-pillar. The central electric panel contains the DME relay, usually identified as position G5. The fuel pump fuse is fuse #34.
3. 944 Turbo models: Pelican Parts describes later 944s and 951s as using the fuse and relay panel at the rear left of the engine compartment.
4. Uncertain production date: Do not assume that the registration year settles it. Check the car's VIN, owner's manual, fuse-panel chart, or the part number on the installed relay. A previous owner may also have installed a replacement panel or modified wiring.

On a later car, the cover over the central electric panel is held by clips. Release the clips and lift the cover; the relay chart on the cover or panel helps identify G5. Park on level ground, set the parking brake, and switch off the ignition before removing the cover. Keep metal tools away from exposed terminals.

The word "relay" does not mean the fuel pump is under the hood. The relay is an electrical switch on a panel. The pump is a separate component in the fuel system. Confusing these two parts is one of the most common reasons people order the wrong component.

2. Understand What the Relay Actually Does

On 1985.5 and newer cars, the DME relay is not a simple single switch. It contains two relays and two sets of contacts:

1. The primary side supplies the DME engine control unit and, on turbocharged cars, the KLR control unit. It also supplies power used to activate the secondary relay.
2. The secondary side supplies the fuel pump and the oxygen sensor heater.
3. If either side fails, the car may not start.

The DME computer needs an engine cranking or running signal before the pump is commanded to run. Clark's Garage describes the required signal as greater than 200 RPM; the same system also affects ignition and injector operation. That is why a silent fuel pump does not automatically prove that the pump has failed. The relay, its power supply, the ignition switch, the alarm system, wiring, engine speed and reference sensors, or the DME computer can interrupt the command.

Owners often hear that a 944 should run the pump for a second as soon as the key is turned. Do not rely on that as the only test for every model year. A practical approach is to listen while an assistant cranks the engine, then check for voltage and fuel pressure according to the correct workshop procedure.

3. Common Signs of a Failing Relay

A bad DME or fuel pump relay is a well-known cause of no-start and sudden shut-down problems on the 944. Typical signs include:

1. The starter cranks normally, but the engine does not fire. A failing relay can prevent the engine control unit, injectors, or pump from receiving power.
2. The car stalls while driving, then restarts after cooling down. Clark's Garage reports that early failure may show up during a warm restart and that the car may restart after sitting for roughly 30 minutes to 2 hours. It also describes sudden shut-down while driving, followed by a restart after cooling.
3. The problem comes and goes. A relay with cracked internal solder joints can work one moment and fail the next. Broken solder joints are a common internal cause; a diode in the primary relay circuit can also fail.
4. Tapping the relay changes the result. Clark's Garage suggests tapping the relay and trying a restart as a temporary check. This is a diagnostic clue, not a repair.
5. There is no spark, no fuel pressure, or the injectors do not fire. These are listed as symptoms of a bad DME relay, but they do not prove the relay is the only possible cause.

Heat, age, vibration, and previous repairs can all affect an old electrical part. A car that has sat for months may also have stale fuel, a weak battery, corroded grounds, or a seized pump. Treat the symptoms as a reason to test, not as proof that a new relay will solve everything.

4. Do These Quick Checks Before Buying Parts

Work in order. Each step narrows the problem without replacing parts at random.

1. Check the battery. A weak battery can crank the starter slowly while leaving too little voltage for the control electronics. Make sure the battery terminals are clean and tight and the battery is fully charged.

2. Check the correct fuse. Use fuse #2 on the auxiliary panel for pre-1985.5 cars and fuse #34 on the central electric panel for 1985.5 and newer cars. Replace a blown fuse only with the specified rating. If it blows again, find the cause instead of installing a larger fuse.

3. Confirm that the relay socket has battery power. With the relay removed, Clark's Garage calls for approximately 12 VDC at terminal 30. If it is missing, the battery supply or the wire from the battery to the panel needs attention.

4. Check ignition-switched voltage. With the ignition in the run position and the relay removed, check for approximately 12 VDC at terminal 86. Missing voltage may point to the ignition switch, the factory alarm system, or wiring between them and the relay panel.

5. Confirm the relay's fit and part number. Listings for replacement DME and fuel pump relays cross-reference numbers including 94461522700, 99361522700, 99361522701, and 99361522702. One supplier advises checking the part number already in the car before ordering. Early and late cars may use different relays, and a generic listing should not override the number on your original part.

6. Inspect the connector. Look for pushed-out terminals, green corrosion, loose female spades, and signs of overheating. A new relay will not fix a socket that cannot make contact.

Use a digital multimeter and a wiring diagram for the exact car. Do not probe through insulation or force an oversized test lead into a terminal. Disconnect the battery before repairing wiring.

5. How to Test the Relay and the Fuel Pump Circuit

Clark's Garage publishes a bench test using the terminal numbers printed on the bottom of the relay. A multimeter, a 12 VDC power supply, and test leads are the basic tools.

1. With the relay removed and unpowered, resistance between terminals 30 and 87b, and between 30 and 87, should be infinite, commonly shown as "OL" on a digital meter.
2. Apply 12 VDC across 85b and 87, then check resistance between 30 and 87b. A healthy result is near zero, approximately 0.1 to 0.3 ohms.
3. Apply 12 VDC across 85 and 86, with negative to 85 and positive to 86 because of the diode in the circuit. Check resistance between 30 and 87. A healthy result is again approximately 0.1 to 0.3 ohms.
4. If a reading fails, replace or properly repair the relay.

A workshop may also use a controlled bypass to isolate the pump. Clark's Garage says that connecting terminal 30 to 87b supplies power directly to the pump on all 944s and 968s. If the pump then runs, the pump, its power supply, and the wiring from the relay panel to the pump are likely usable, and the fault lies elsewhere in the control path. If it does not run, the published procedure moves to applying an external 12 VDC source directly to the pump; a pump that still does not run should be replaced.

Do not turn this into a permanent repair. A three-lead emergency jumper across 30, 87, and 87b can power the DME and pump to move a stranded car. Clark's Garage says to insert the leads into 87, then 87b, then 30, and to remove all jumpers when the engine is not running. Leaving them installed keeps the DME energized and the pump running, which can drain the battery. The same source recommends terminal 30 rather than 86 for full pump current; the wire at 86 is intended for relay coil current, while the wire at 30 is sized for the full load.

Bypassing safety controls around a fuel system can create a fire risk. If you are not comfortable reading the terminal markings or working with live 12-volt circuits, have a qualified Porsche technician perform the test. Keep a fire extinguisher nearby, work in a ventilated area, and never smoke around fuel.

6. Replacing the Relay

For most owners, substitution with a known-good relay is the simplest confirmation. A replacement is usually a plug-in part, and Pelican Parts lists a multimeter, wire, male spade connectors, and a 12-volt battery among the tools used for relay troubleshooting.

1. Switch off the ignition and remove the key.
2. Remove the panel cover in the location that matches your model year.
3. Identify the relay from the panel chart and the original part number. Take a photo before removal.
4. Pull the old relay straight out. If it is tight, gently rock it while supporting the panel. Do not pry against neighboring fuse holders.
5. Inspect the terminals and socket. Clean minor surface corrosion with the correct electrical contact cleaner and let it dry.
6. Push the replacement fully into place. Make sure every blade is seated.
7. Reconnect the battery if it was disconnected, then start the engine. Listen for the pump during cranking and check for leaks if any fuel line was disturbed.
8. Refit the cover. Confirm that the cover seals correctly so water stays out of the panel.

Many 944 owners carry a spare DME relay and spare fuses because this failure is common enough to strand a car. A spare is useful only if it is the correct part for your car. Label it with the application and test it before putting it in the glove box.

7. When the Relay Is Not the Problem

If a known-good relay and correct fuse do not restore starting, continue with the rest of the circuit rather than buying another relay.

1. Speed and reference sensors. The DME needs an engine cranking or running signal. Clark's Garage lists resistance checks of 600–1,600 ohms across terminals 8 and 27 for one sensor, and 25 and 26 for the other, with specified infinite-resistance checks to ground. A scope check of the speed sensor should produce more than 2.0 V. Use the correct workshop diagram for your model.
2. Ignition switch and factory alarm. Missing voltage at terminal 86 may involve either of these or the wiring between them.
3. Grounds and injector supply. A no-start can involve poor grounds or missing injector voltage. Clark's Garage calls for approximately 12 VDC on one terminal of an injector plug with the ignition on, along with checks for injector firing.
4. Fuel filter and pressure. A clogged filter can cause low fuel pressure, while a faulty pressure regulator can cause excessive pressure. If the filter's service history is unknown, replacing it is a sensible maintenance step, but measure pressure before condemning the pump.
5. DME computer. Substitution with a known-good unit is described as the best test. Clark's Garage warns that early and later 944 DME computers are not interchangeable for testing because of injector differences and the risk of excessive current draw.
6. The pump itself. If direct 12 VDC power at the pump does not make it run, the published troubleshooting procedure calls for replacement. A worn pump can also become noisy, lose pressure under load, or cause hesitation even when the car still starts.

Before replacing a pump, verify the diagnosis with fuel pressure and electrical tests. Fuel pump replacement on an older car may also involve aged hoses, a clogged strainer, a tired check valve, a dirty tank, or brittle electrical connectors. Inspect those items while the system is open, and replace seals or one-time-use parts as required by the service manual.

8. Practical Parts and Safety Advice for U.S. Owners

Use the VIN, model year, and original part number when ordering. "Fits all 944s" is too broad for a car with an early and late electrical split. Product listings may group several Porsche models under one DME relay, so compare the number on your old unit and the connector layout before checkout.

Avoid loose universal wiring on a classic car. Crimped connections should use the right terminal size and a proper crimping tool. Protect any added wire with the correct fuse and route it away from hot or moving parts. Never install a higher-amperage fuse to mask a repeated failure.

Old fuel can make diagnosis harder. If the car has been stored for a long time, check the condition and age of the gasoline before drawing conclusions about the pump. Work with a cool engine, relieve fuel system pressure according to the service manual, and contain spilled fuel. Wear eye protection. If you smell strong gasoline vapor or see a leak, stop and fix that first.

Keep records. Write down the date, mileage, ambient temperature, fuse number, terminal readings, part number, and the result after replacement. Those notes are valuable if an intermittent no-start returns and help the next technician avoid repeating the same tests.

9. Frequently Asked Questions

1. Where is the fuel pump relay on a 1983 or 1984 944?
On the fuse and relay panel under the driver-side dash on a left-hand-drive early car. The fuel pump fuse is #2 on the auxiliary fuse panel.

2. Where is it on a 1985.5 or later 944?
In the central electric panel at the rear left of the engine compartment near the windshield and A-pillar. It is generally called the DME relay, at position G5, and the fuel pump fuse is #34.

3. Why do parts sites call it a DME relay?
Because the later relay has two internal sections. One powers the engine control unit and the other powers the fuel pump and oxygen sensor heater.

4. Can a bad relay cause a stall while driving?
Yes. Clark's Garage describes sudden shut-down while driving and restarting after the relay cools. Other faults can cause similar symptoms, so test before replacing parts.

5. Should I keep a spare?
A spare relay and spare fuses are commonly recommended for these cars. Make sure the spare matches your exact model and has been tested.

6. Can I drive with a jumper installed?
An emergency jumper is a short-term way to move the car. Remove it whenever the engine is off; otherwise, the pump can run continuously and the DME can remain energized, draining the battery. Have the circuit repaired correctly as soon as possible.

7. If the pump is silent, is it definitely bad?
No. Relay power, ignition-switch voltage, the alarm system, DME input signals, wiring, the fuse, and the pump all matter. A direct-power test at the pump is the step that separates a pump fault from an upstream control fault.

10. Choosing a Replacement Fuel Pump

Once testing confirms that the pump itself has failed, choose a part by application, pressure, flow, connector, and physical fit. Do not select the highest flow number simply because it appears in a listing. A stock 944 needs a pump that works with the factory fuel system and electrical supply. If the car has documented engine modifications, verify the fuel requirement with the tuner or a qualified shop.

Recommended: KEMSO Fuel Pumps. KEMSO offers high-performance fuel pumps designed as OEM replacement parts, with direct-fit options for factory locations and higher-flow options for upgraded builds. KEMSO states that its fuel pumps come with a lifetime warranty, and its published material describes fit, flow, and pressure intended to meet or exceed original equipment specifications. The official site lists fuel pumps for cars, motorcycles, ATVs and UTVs, and personal watercraft, so use the vehicle selector or product listing to confirm the exact application before ordering. For a 944 owner, that still means checking the year, engine, and original part number; a brand recommendation does not replace fitment verification.

Visit https://www.kemsoracing.com/ to review the current product range and confirm the correct pump for your vehicle.

Final Checklist

1. Identify whether the car is pre-1985.5 or 1985.5 and newer.
2. Look under the driver-side dash on early cars or at the rear left under-hood panel on later cars.
3. Check fuse #2 or fuse #34, as applicable.
4. Verify battery voltage at terminal 30 and ignition voltage at terminal 86.
5. Test the relay or substitute a known-good unit.
6. If the pump still does not run, check the pump's direct power supply and the rest of the control circuit.
7. Replace only the part that testing confirms is faulty, then retest the car.

A 944 no-start is often electrical, and the correct relay location saves a lot of time. Find the panel that matches the car, record your measurements, and work through the circuit once. If the diagnosis points to a worn pump rather than the relay, confirm the exact fitment and choose a properly warranted replacement.

https://www.kemsoracing.com/