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Join Date: Oct 1998
Location: Quilcene, WA, USA
Posts: 123
Fuel pump problems - HELP!

I just got my '75 1.8L down off the blocks and was trying to crank it up for the first time in about 10 months. During this time, engine, interior, wiring harness, everything had been out.

When I turned on the key, no fuel pump whirr. Everything else worked electrically that I could check. After 6 or 7 tries, the fuel pump came on and after waiting for the fuel to make its circuit and blow the air out of the system, she started right up!

Next time I tried it - no fuel pump again. Thought maybe I had a dead spot in the fuel pump (no problems before the rebuild), but when I put 12v to it directly it works fine. Doesn't appear to be any power to the pump (not 100% sure, can't find my multimeter).

I opened up the relay box and found that the two fuses were gone so I replaced them - no difference. Also noticed that there were only 2 relays in the box even though there are spots for 4 relays (I also seem to have the earlier 911.615.109.01 relays). There was no relay in the spot for the fuel pump relay. Putting one there didn't help either.

Should there be 4 relays in there? (If so why did it run fine before?)

I hope to find my multimeter (I think it is on my boat) and do some more digging, but in the meantime, any helpful suggestions????

This one is especially frustrating.
Old 09-03-1999, 09:22 AM
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I had a similar problem with my '74 2.0. After dropping the engine out to change the clutch, fuel pump would sometimes not work. Turns out I had scraped a bit of the insulation off of a wire, it bounced around sometimes touching metal and was shorting out the fuel pump circuit. As to the number of relays, I think two relays in the relay box is the correct number. Good Luck!
Old 09-03-1999, 11:22 AM
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The four relays on the relay board are for the heater blower, the rear window defogger, the fuel pump, and finally the fuel injection controller. The fuese are for the heater blower and the rear window defoger, I think.

I had problems on numerous occasions with my fuel pump. The power goes from the ingnition switch to the fuel injection power relay, through the FI control box, to the fuel pump relay, and then to the fuel pump. My problems generally related to the wires between the FI control box and the relay board. The wires got brittle with age. I had to carefully cut the plastic tube off of the wiring harness to find the broken wires and then splice them. Once I had to drive 600 miles the next day and did not have time to find the problem, so I actually ran a wire from the battery through a fuse into the passenger compartment to a switch and then to the fuel pump. It got me home where I finally found the problem.

On another occasion the fault was actually a bad ground for the FI controller. On the top of the engine at the transmision end is a three pronged ground lug. I had one wire break at the connector and the fuel injection controller would not turn on, therefore no fuel pump.

Whatever you do, remember that when the key is first turned from stop to run, the fuel pump will only run for a second or two. It will not run again until the engine is running.

Good Luck!

Bobbitt
Old 09-03-1999, 01:49 PM
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Well if you had a D-jet we would be all set but this L-Jet mumbo jumbo...

O.K. from my failing memory (amazing how a receeding hair line can make you fell old) the D-Jet uses one of the two fuses in the relay board, and one of the four relays (the other fuse is for the heater blower, the other relays are for the ECU power, Rear defrost, and I think the last one is also for the blower) for power. The pump turns on for a few seconds to build preessure then turns off until the engine RPM is greater than 100 RPM. Now that said, you have a L-Jet.

I THINK that the fuel pump relay is not in the relay board but is one of two "combonation relay" that is under/next to the battery. It looks like two relays stuck together. The L-jet pump is controlled by the opening of the air flow meter. Manually opening the vane (or the vaccuum caused by the cranking motor) should send a signal to the pump to opperate.

So what I would do (that means alot) is to clean the contacts on the combo relay, then wack it real good, just to make my self fell better . Clean the ground contact for the pump (it is a welded on tab under the tank but you can "just" reach it though the access hole) and both the contacts on the pump. Turn the key on and manually open the vane meter to see if the pump turns on.

Also look at the 914 fans web site. There is a fuel system tech article that is about the pump. Sorry I can't remember if it only about the D-Jet or not.
Old 09-04-1999, 12:01 AM
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You need to look to see if the heater blower comes on when you pull the defroster lever. If not the circuit is broken. As JPN pointed out they are on the same circuit.
Old 09-04-1999, 06:04 AM
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JP's got it here, folks. The 1.8 only uses the heater blower relay on the relay board. And the rear defroster relay if the defroster is there. The other two don't do anything--they're "on-board spares".

The article on Tim's Fan Page is about the D-jet fuel pump control circuit.

The L-jet system works off of the air flow meter. When the flap opens at all, two of the contacts in the plug get crossed. That in turn signals one of the relays in the "dual relay" near the battery, which closes and sends power to the pump.

I agree with JP: clean up the connections, and tap the relay to see if that has any effect. You can also push the flap in the air meter with the ignition "on" to see if the pump runs.

Good luck!

--DD
Old 09-04-1999, 08:43 AM
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Yes the Ljet is a bit different.
When the engine is running the air vane is open and energizes the Fuel Pump relay. The other way that the fuel pump is activated is there is a yellow wire with a single female spade connector (lighter gauge than the yellow wire in the right rear multi- connector which is to the starter) This is connected to the left rear 4 male spade connector block on the relay board. The position is the right side rear most connector. The reason for this is to energize the fuel pump during any cranking of the engine.
Bill K.
Old 09-05-1999, 03:38 PM
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Thanks everyone! I do have an L-jet. My big thanks to Tom at Pelican. I gave him a call Friday and he told me to quit looking at the relay board and look over by the battery.

It was just a loose connection. When I wiggled the plug, away she went. I had a wonderful little spin 5 minutes later. Top off, wind in my hair.

There is still a lot of work to finish my restoration, but it is great to be back on the road again! Many, many thanks to Pelican and all you folks out there willing to share your "experiences".

Ascaris
Old 09-05-1999, 07:28 PM
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