Trust Issues, Can I trust it? Options

[sdoolin]

Went to start the 914 a couple of days ago and noticed that the fuel pump sounded a little weak, didn't seem to run consistently when key turned. Car started, then died (as if it ran out of gas). Then would not start again. Cranked, but would not fire.

Luckily it was in the barn and not far away from home.

Went to push it out of the way last night (to get it on the lift) and it started right up. Damnit! I'd rather it stayed broken. It starts consistently now - even though the fuel pump still sounds weak.

So now I can't trust it to drive it anywhere for fear it'll not start somewhere far away.

Gonna check/replace the fuel pump and filter. Any other thoughts from the collective knowledge base?

[Mikey914]

Just he AAA and drive it. You can replace the pump, but easier to find the problem when its inop.

[walterolin]

Need to eliminate the relay board first. Corroded/loose connections there could be the cause. Run a fused wire from the battery to the the pump and see what happens.

[Tom_T]

Yeah, somehow cars always know when they're going to the shop or getting looked at & stoop.

Check fuel flow first before replacing parts on that side, cuz intermittent is more often on the electrical side - both ignition & ECU/EFI, so that all should be checked before throwing a load of new parts at anything.

One exception on the fuel side - if it was hot there then & you had driven the 914 before the problem (I know some areas are still very hot), & if you have an early 70-74 with the fuel pump in the engine bay - then it could be vapor lock & will want to move the fuel pump up under the fuel tank near the tunnel & behind the steering rack cover. AA sells a ready to go kit for that.

Basically in hot weather + engine bay heat overheats the fuel pump & it causes vapor bubbles inside & in lines & you have to wait for it to cool down & fuel to re-liquify. Porsche recognized this later & issued a Service/Tech Bulletin for the relocation noted above in the mid-70's & relocated the fuel pumps to the front on all 75-76 cars.

It happened to me once at a quick stop in Blythe CA in the SoCal desert summertime, which turned into an extended lunch stop while the fuel lines & pump cooled. The next week I had the pump moved & nary a problem since.

PS - You should also check & clean all the elec. connections throughout & at battery, & at the relay board as noted above, cuz they can corrode & cause problems too. I used to have to do it or have my mechanic do them every 6 months when I lived 3 blocks from the beach, more often was due to the salt air. Wurth or other elec. connection oil or elec. grease helps keep them clean.

914s can be very reliable DDs, so don't give up.

Good Luck! (IMG:style_emoticons/default/beerchug.gif)
Tom
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[Tom_T]

PSS - Maybe if you changed your title to "Starting Issues...." - instead of trust issues, you'll get more on point replies.

BTW - I've always loved that Blue! (IMG:style_emoticons/default/drooley.gif)

(IMG:style_emoticons/default/beerchug.gif)
Tom
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[chandler1969]

I feel your pain. Drove mine to work this morning, about 45 minute drive. Had to stop at McDonalds for a sweet tea cause thats how we roll in the south.

Went out to lunch and back to work.

Then headed home after work but needed to stop at the store. Thats about a 45 minute drive. Weather - sunny and low 80s. I was in the store for about 30 minutes. The car ran great all day. It does on occasion stumble in de-acceleration. I dont know if that is important information or not. When I went to start the car to get home, it started then died. Started then died. Did this several times until it started acting like it didnt want to fire at all.

I got a ride home and let the car sit. Went back after about an hour or so. I used some starter fluid. The car fired up and ran for about 10 seconds then died. After several failures of starting, I decided to get it towed home.

This is a 74 with a 2.0. I will try to start the again in the morning and go from there.

I need to check the fuel pump. I dont even know where it is. I rememer my 75 1.8, the fuel pump was in the front trunk and I could hear come when I turn the key. This one I assume is still in the engine compartment.

[euro911]

Look under the engine bay tin, passenger side fire wall area

[chandler1969]

and of course when I went back out to meet the tow truck, I tried it and it started right up. I'll add moving the fuel pump to the list of things to fix :-)

[EdwardBlume]

I had an intermittent fuel pump. Replaced it with a 75-76 and now life is good.

[eyesright]

Here's my show and tell...

I drove 700+ miles to Colorado in July to visit friends. When I got there the fuel pump was making a buzzing noise that got a little worse as I drove around town for a couple of days. Should I ignore things and head back to Oklahoma?

Maybe I better have a back up plan. The local FLAPS can get me one in 2 days. The local indy Porsche shop will have one by noon that day. Hmmm, I think I should at least carry one with me. So $350 later, I put the new fuel pump in my tool box and start for home......and of course the old fuel pump isn't buzzing now and gets me home just fine and has been trouble free since. So I guess I have a new fuel pump on my shelf for whenever...

You never know.

[bigkensteele]

If it is a 1.8, it could be the fuel pump relay. This is located on the battery stand. Mine was failing intermittently. I don't know how you would test it, but I replaced it and never had the problem again.

[sdoolin]

Fuel pump is completely INOP now, makes no noise when key turned. I have removed, cleaned contacts and replaced all replays on the relay board (on drivers' side engine compartment). All fuses check OK and the wiring/connector at the pump appears OK. It is a 2.0 so no relay on battery side of engine compartment.

Looks like I need to buy a pump (and filter), and maybe those cool SS lines from Tangerine...

Oh - this was/is not a vapor lock issue - car had been sitting for days when problem first manifested itself and is cool now and no pump.

Thanks for all replies, car goes up on the lift tonight...

[sdoolin]

Can I apply 12V DC (from a known good battery) across the pump and expect it should spin?

[walterolin]

Can I apply 12V DC (from a known good battery) across the pump and expect it should spin?

Yes

[euro911]

The relay board would be on the driver's side in the engine compartment. If you don't have a spare relay, you can 'borrow' one from one of the headlight motors until you get some new spares (IMG:style_emoticons/default/idea.gif)

[sdoolin]

I had tried the relay swap deal with no luck, and 12V DC across the pump produces nothing. Well, actually the pump spun very slowly and irregularly when I first applied 12V, then nothing.

Ordering a pump and related bits today...

[sdoolin]

As I somewhat suspected (and prolly many of you too) this is not as simple as buying a replacement pump, installing it, and living happily ever after.

Digging a little deeper, I do not get 12V across the FP connecter when key is switched on (I get like 0.2V). I swapped the headlight and FP relays on the relay board and the headlights work (they did before the swap also). Connecting a new (borrowed not bought) FP and switching the key on I get nothing at the pump.

So I can surmise that the relay is good and that I either have 1) a bad power lead, 2) a bad ground, or 3) a toasted relay board (I have several spares).

I have done some searches and it looks like some folks run a power line directly to the pump from the relay board?

Relay board comes out (again) today.

[Spoke]

Digging a little deeper, I do not get 12V across the FP connecter when key is switched on (I get like 0.2V).

I looked through your thread and missed the part of whether you have FI or carbs.

If FI, the FP only runs for 2 sec after the key is turned on and you would expect 0V when the key is left on.

Before you try to swap everything, with the engine on or running, measure the voltage at the FP from the POS to NEG terminals. Also measure at the FP from POS to chassis.

If you don't get what you expect, follow the wires back to the battery, measuring voltages from whatever you're measuring to chassis.

Many times solving electrical issues like this is not magic. You have a bad connection somewhere. You need to find it. It could be a board connector, a wire connector, a relay connector, and even a fuse. Follow the wiring from the FP to the battery. Somewhere is your issue.

Take your time and do the troubleshooting right. You can swap stuff out all day and if you're not touching the issue, you're just verifying that a good component is good.

[sdoolin]

Digging a little deeper, I do not get 12V across the FP connecter when key is switched on (I get like 0.2V).

I looked through your thread and missed the part of whether you have FI or carbs.

If FI, the FP only runs for 2 sec after the key is turned on and you would expect 0V when the key is left on.

Before you try to swap everything, with the engine on or running, measure the voltage at the FP from the POS to NEG terminals. Also measure at the FP from POS to chassis.

If you don't get what you expect, follow the wires back to the battery, measuring voltages from whatever you're measuring to chassis.

Many times solving electrical issues like this is not magic. You have a bad connection somewhere. You need to find it. It could be a board connector, a wire connector, a relay connector, and even a fuse. Follow the wiring from the FP to the battery. Somewhere is your issue.

Take your time and do the troubleshooting right. You can swap stuff out all day and if you're not touching the issue, you're just verifying that a good component is good.

Thanks for the suggestions. It is a stock 2.0l FI car. I have been reading many threads on FP elec. issue diagnosis and I am following many of those instructions.

Jumpering things on my original relay board produced unwanted results, so I swapped the relay board to another one where jumpering exercises produced desirable results, and all is well, except the FP runs "irregularly". So I pulled the gas tank. Really. Decided to go "all in" with new fuel lines/pump/sock/everything from Tangerine. The lines are the OE rubber ones in the tunnel and I have been worried about them since I purchased the car.

So while I think the relay board was my root cause issue, I have pretty much taken the fuel system apart for a complete makeover.