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Location: Williamsburg, VA
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Fuel pump relay

Fuel pump stopped last night ??????????

After some looking around and checking things, I think I know where the problem is...Where does the + signal to activate the fuel pump relay come from? I have verified all other wires and connections.

If I jumper across the relay connections I can make the fuel pump run.

I think it's the signal from the ECU???

Does the same signal to activate the fuel pump go to another location? Anything else on this signal?

Cheers

Kerry
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Old 08-04-2003, 04:31 PM
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I may not be able to answer your question but here goes: If you have a 1.8, the fuel pump only runs when the engine is running. As the air flap moves, it triggers the fuel pump to run. You can check by turning on the ignition, removing the black cap on the air flow meter & moving the meter needle.

Unfortunately, I can't answer your question if you have D-Jet 1.7 or 2.0

Vern
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Vern
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Old 08-04-2003, 05:13 PM
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Thanks..

I keep forgetting to indicate this in my Q's

I have a 1974 with a 2.0L D-Jet..


Also, I have power to both sides of the fwd most fuse on the engine relay board. When does the aft most fuse get power? With the key on the aft one has no pwr?
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Kerry (Back on the road, sort of)

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Old 08-04-2003, 05:18 PM
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On a D-jet car, the fuel pump power comes from the fuel pump relay on the relay board. The fuel pump relay is triggered by the ECU supply or removing a ground from one of the "switching" contacts on the relay. The relay always has power going to its "input", regardless if the car is running or not. So if you jumper the relay the pump should always run.

Relay board diagram:
http://www.pelicanparts.com/914/parts/Electrical/914_electric_73E.jpg

Note that pin 86 of the fuel pump relay goes to the four-pin connector which the ECU wiring harness plugs into. Pin 85 of the fuel pump relay is hooked up to the output of the FI power relay, so it will have +12V any time the ECU is getting power. Pin 87 is the output from the relay and goes to the pump, and pin 30 is the input to the relay. It is powered by the rear-most fuse, and should have power all the time.

Sounds like you need to check the red wire hooked up to pin #14 of the front 14-pin connector on the board.

BTW, the fuel pump power supply also feeds the Auxiliary Air Regulator. Note it hooks over to pin #12 of the 12-pin connector on the right-rear of the relay board.

--DD
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Old 08-05-2003, 08:29 AM
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Thanks Dave..

I now have power to both fuses on the relay board. BUT I still have no power to the fuel pump.

If I force the fuel pump relay to make contact the pump runs. It seems like the signal form the FI relay is not getting to the pump relay????

Any more thoughts..

Thanks again
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Old 08-08-2003, 11:49 AM
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Ummm...bad relay?
Old 08-08-2003, 12:30 PM
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Like I said on the "other board", unplug the four-pin connector and ground the left-front pin on it. The pump should run when the key is on. If not, then unplug the relay and check the relay socket pin #85 to see if it has +12V.

Then plug the connector back in again (turn the key off first), and poke a probe from your multimeter down to the back side of that same pin. Have someone turn the key from off to on. For about 1.5 seconds, you should see that pin get grounded by the ECU.

Tim's 914 Fan Page has a long text article about D-jet fuel pump troubleshooting. http://www.914fan.net/fuelpump.html

Brad Anders has a flowchart for troubleshooting D-jet fuel pump problems. http://members.rennlist.com/pbanders/FPChecklist.htm

--DD
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Old 08-08-2003, 12:40 PM
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Thanks I'll give that a shot his weekend.

I have swaped in 3 relays and no change so I ruled out the relay. The relays are not new but worked before swapped out.

Thanks again guys

Kerry
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Old 08-08-2003, 02:18 PM
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FWIW, I had fits trying to track down the same type of fuel problem, and it turned out to be a bad connection across the fuse on the relay board. Double check it to be sure. Mine showed voltage but there wasn't enough punch to make the pump go.
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Old 08-08-2003, 07:48 PM
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Links are dead

Dave,

Could you please refresh the links on the attachments mentioned in this article?

Thank you!
Respectfully,
Cary Conrad
Boston MA
Old 08-11-2018, 07:25 PM
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Archived version of the 914 Fan Page article: https://web.archive.org/web/20000929210032fw_/http://www.914fan.net:80/fuelpump.html

Supposedly this page has Brad Anders' fuel pump troubleshooting slides, but I can't see them. https://members.rennlist.com/pbanders/FPChecklist_frame.htm

Not sure what the issue is with that. Searching through archive.org produces basically the same results...

--DD
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Old 08-12-2018, 04:15 PM
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