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Posted by: #1RAGE May 7 2007, 11:01 PM

Just since this last weekend, my 914 has been having trouble starting. It turns over and over but doesn't start. Two out of three times trying, I got it to start. The last time I noticed just before it finally started, I heard a buzzing sound come on. Normally I hear this buzzing sound coming from the front of the car when it is running. Is that noise coming from the fuel pump?

I have heard that some people relocate the fuel pump to the front trunk area. If that is the case with my car, would the fuel pump likely be underneath the tank?

Just to make it clear. Normally I hear a buzzing noise coming from the front trunk / gas tank area. Recently I have been having trouble starting the car but just before it does the noise appears... which leads me to think it might be the fuel pump.

I'm not much of a mechanic. I remember looking for the fuel pump a couple years ago and couldn't find it in the engine bay; this also leads me to believe it is up front somewhere.

Thanks in advance.

Posted by: porsche914blue May 8 2007, 09:11 AM

That probably is your fuel pump. Mine was relocated to the front (74) by the PO and I can always hear the pump run for a couple of seconds when I turn the key. Yours may have been moved to under the tank or to the front trunk.

I had the same issue, car wouldn't start sometimes and when it wouldn't I noticed that I didn't hear the pump running when I turned the key. Ended up being a failing relay on the relay board in the engine compartment.

The fuse and relay for the fuel pump are on the relay board in the engine compartment. Make sure the fuse, fuse holder tabs, relay, and relay socket are clean and not oxidized. Check the electrical connection at the pump too.

Posted by: mstein95 May 8 2007, 09:16 AM

BTDT - I would start there.

When mine FP died it would start by providing enough fuel pressure to start the engine but couldn't sustain the pressure and the engine would die. Mine is located in the front so the "buzzing" coming from under the fuel tank is your FP. Also, while you are there - check your fuel filter. If dirty, could be contributing.

Posted by: Travis Neff May 8 2007, 12:36 PM

FI or carbs? if FI, I would first suspect your relay board for bad connections underneath. Remove the relay board and look underneath to see if the potting (black tarry stuff) is falling off - if it is you may need to resolder some of the connections underneath.

Posted by: swl May 8 2007, 04:46 PM

I'm with Joel. Intermittent no buzz is most likely electrical and not the pump itself. Fuse and relay are the first suspects that come to my mind. Sounds strange to think of a fuse as intermittent but it is the oxidization thing combined with heating and cooling that can do it. Test the relay by replacing with one from the headlight motors.

This is assuming of course that yours is standard FI - all bets off if it is carbed. From your avatar it looks like a 73 - d-jet?

Posted by: #1RAGE May 8 2007, 09:46 PM

Thanks guys.. I think we're on the right track but I took a look and I'm confused now.

Here is a picture of my relay board. I'm also posting a picture of a picture a relay board from my Haynes manual to show what's what. Notice how both the power supply relay (for fuel injection) [#11] and the fuel delivery pump relay [#12] are missing? There's no way they could have fallen out.

The two fuses seem to be fine, although there are two 16A fuses instead of a 15 & 30.




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Posted by: Marlow May 8 2007, 10:22 PM

Are you running carbs?

It would seem someone has wired your fuel pump separately. If that's the case you'll have to trace the wiring from the pump back to the power source. There's also the possibility that your fuel pump is failing, although I would bet on a wiring/connection problem.

Posted by: KELTY360 May 8 2007, 11:30 PM

You may find your fuel pump behind the steering rack cover underneath the car.

Took me weeks to find mine last year, I was afraid I was going to have to pull the tank.

Posted by: #1RAGE May 8 2007, 11:53 PM

It is FI. I guess I'll have to look for my fuel pump.

Posted by: Dave_Darling May 9 2007, 09:51 AM

You didn't mention you were running L-jetronic EFI. The 1.8 uses a different EFI setup--the single wire on the four-pin connector gives it away.

The "dual relay" that hangs off of the battery tray takes care of providing power to the ECU and power to the fuel pump. The 1.8s fuel pump should run under two circumstances:
- when the starter is cranking
- when the flap in the air flow meter is open

It shouldn't do the ~1.5 second "buzz" when the key goes from off to on like D-jet does.

--DD

Posted by: #1RAGE May 10 2007, 08:48 PM

I appologize for not giving information my car. For some reason I thought my profile showed my car info but I was thinking of another forum.

It is a 1974 with the 1.8L.

Dave, I found that dual relay. It wasn't attached to anything and was just laying on top of the engine. I unclipped the connectors and removed it. Visually it appears to be fine.

I did notice 3 wires that weren't connected to anything, although it looks like they were cut, not broken. I'm not sure where they come from but the 3 are bundled together and then they run into another wire housing that contains other wires so I'm not sure where it leads to.

I can't get it started at all anymore. Still no indication of the fuel pump running.

I'm attaching a picture that shows the dual relay and the disconneted wires in the bottom left corner.



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Posted by: Dave_Darling May 10 2007, 09:22 PM

Those look to be fuel injection wires--they're white, which the EFI wires pretty much all are. I also see a number (12?) which may also be a clue.

The dual relay must be plugged in for the EFI to work at all. So if you've unplugged it, plug it back in!

To force the fuel pump to run, remove the top of the air filter housing. Then, with the key on, reach into the air inlet from the housing to the air flow meter and push on the flap in the meter. You should hear the pump run. If not, start checking for what is wrong there.

Chase the wire bundle that has those three cut-off wires in it--where does it go?

--DD

Posted by: #1RAGE May 11 2007, 07:00 PM

Yes, I believe that is a 12 on the wire.

I pushed the flap and it didn't start the fuel pump but it did make a clicking noise every time I pushed the flap open. I think the clicking sound was coming from the relay but it was hard to check by myself so I will have to look at it again when I have someone here to help me.

Could this be a sign that it is something after the relay? Either the wiring to the fuel pump or the fuel pump itself?

This weekend I'll spend some more time trying to figure it out. I still don't know where the fuel pump is exactly.

Thanks again Dave, I really appreciate the help!

Posted by: Dave_Darling May 11 2007, 07:48 PM

The click is probably the dual relay--if it is, then whatever is keeping your pump from running is "downstream" (electrically) from the relay. Could be the pump, could be the wiring... When you find the pump, jumper +12V and ground directly to it. If it doesn't run, it's a goner.

--DD

Posted by: #1RAGE May 15 2007, 11:36 PM

Alright, made some more progress today.

Got a good buddy of mine to help me. We pulled the gas tank out and the fuel pump was underneath it.

We're not experts on the electrical stuff so hopefully someone here can help.

We disconnected the fuel pump and hook it up directly to a battery and it seemed to work fine. When we pumped a bit of clean gas with the pump out of the car, the gas coming out was very dark and dirty looking... that can't be good, can it?

Then we tested the voltage of the wires going to the fuel pump, at the fuel pump end. We got a reading of 0.25 V no matter what position the key was in. When we unhooked the white connector on that relay (picture in my earlier post), we got 12 V but again no difference with the key on or off.

What does that indicate? Shouldn't I be getting 12 V only when the key is turned on? Is there any way to test the relay?

Thanks!


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Posted by: Dave_Darling May 16 2007, 10:00 AM

The L-jet system does not run the pump when the key is "on". The easy way to force the pump to run is to turn the key on, then push open the flap in the air flow meter. Check for voltage at the pump when you do that (after you've plugged the dual relay back in).

--DD

Posted by: Marlow May 16 2007, 10:10 AM

You might consider cleaning your tank out if the fuel coming out of it is dirty/contaminated. One of the fittings on the bottom of the tank has a strainer sock on it, if it clogs it can cause all sorts of drivability and running issues (the sock is only a few $$ to replace).

Posted by: Garold Shaffer May 16 2007, 10:42 AM

QUOTE(Marlow @ May 16 2007, 08:10 AM)

Posted by: #1RAGE May 16 2007, 08:03 PM

We plugged in the relay, turned the key to the on position, and then opened the flap on the air flow meter. Again we get a constant 0.25 V until the flap is opened. When we opened the flap the voltage went up to about 2.2 V, mind you the battery was pretty weak at this point (around 11.6 V).

Is that normal?

We plugged the pump in again and it won't run at all, even when we unclip the white connector from the relay and we're getting nearly 12 V at the fuel pump. The pump seems to run fine when directly connected to a 12V battery. It doesn't make sense to me.

I want to find another relay to put in and test. I might try get one tomorrow.

Posted by: #1RAGE May 29 2007, 11:41 AM

Can anyone tell me how I would test that dual relay? I have a multimeter and the wiring diagrams from my Haynes manual. I don't where to start testing or even how.

I think the wiring from the relay to the pump is fine because I can get 12 V at the pump end when one connector is disconnected from the relay.

Posted by: Marlow May 29 2007, 01:02 PM

http://manuals.type4.org/ljet/

Go to the 'Components' section, instructions on testing the dual-relay are there.

Not exactly for the 914 but still applicable to L-Jet troubleshooting. I'm not familiar with L-Jet at all, just trying to help out.

Posted by: kwales May 29 2007, 08:13 PM

Square relays are easy. Listen for clicks when activated or......

Take a couple of very small screwdrivers or knife blades and carefuly spread the cover box relative to the base to unlock the cover. Pull the cover up. Plug into the harness, and do your start sequence while looking at the little arm. If it works, the coil turns into an electromagnet, pulls the little arm closed and creates an electrical contact between the arm and another contact.

I hadda troubleshoot my daughters Volvo this weekend. THey run a later version of the Bosch design with a hot wire instead of a flap. With the cover off, both relays tripped in response to key movement to energize the pumps (plural).

Ya might want to open the relay to look inside. My L-jet relay was corroded out from water standing inside and needed replacing. The Volvo guys recommend resoldering the Bosch relays as they the guts become unsoldered over time.

Ken

Posted by: #1RAGE Jun 14 2007, 06:37 PM

Hey thanks!

Took the relay apart and found evidence that water had been in it before. One corner of the circuit board was corroded and rusty. One of the contacts on one relay doesn't make a good connection anymore. Ordered a new dual-relay; it should arrive next week. I hope that's the only problem.

Posted by: #1RAGE Jun 28 2007, 11:08 PM

FINALLY! Got a new relay, put it in, put the tank back in and hooked everything up. Had to run the pump for a little while before I got gas through all the lines but she fired up. I was so excited I went for a drive right away in my blue coveralls without the hood on.

Unfortunately I don't have help right now to get the hood on and I'm going away for the weekend so I'm going to be leaving the 914 in the garage for a few more days.

Thanks so much to everyone for all your help!