Printable Version of Topic

Posted by: SteveL Aug 4 2019, 04:58 PM

Happens when idling or driving. After 5-10 minutes, the engine loses all power, stepping on gas pedal does nothing. Engine dies. Restarts like nothing in wrong in 10 to 60 seconds and runs great for another 10 minutes.

74 1.8 L-Jet. Bosch 2 port updated fuel pump. Just getting it back on the road after being under a cover for 3 years. It had old gas, which I drained and replaced. New fuel filter after new fuel. The fuel pump was replaced 4 years ago, but only about 1000 miles on it. Old gas was, however pumped through it. I just replaced the fuel filter again, thinking it might be clogging up from the lines being rinsed with the new gas, but it made no difference.

Ideas Please??

Posted by: theer Aug 4 2019, 09:12 PM

Hmmm - maybe ignition switch/fuel pump relay is getting touchy.. as in fuel pump is intermittently not getting power?

Do you have to wait the 10-60 seconds? What happens if you try to start immediately after it stalls (or pop start while still rolling)?

Posted by: thelogo Aug 4 2019, 09:19 PM

Most of time after sitting 3 years a tune up is in order

And this could also be fuel sock ?

You mentioned draining the gas and the filter
but not the sock ?

Posted by: SteveL Aug 4 2019, 10:16 PM

I will check the fuel sock, thanks. It did get a full tuneup (cap, rotors, plugs, wires, oil, trans oil, air filter).

I usually do have to wait 10-60 seconds, but a couple of times it started right back up immediately. It is really strange, the engine will keep running for about 5 -10 seconds, but absolutely no power, step on gas, nothing, but still "running", then dies. wait briefly, starts up perfectly.

Posted by: cuddy_k Aug 5 2019, 07:22 AM

I'm no expert, but the symptoms def sound like a fuel delivery issue. Blockage/dirt/restrictions prevent the free-flow of fuel...but if you let it sit for a few seconds, enough seeps by to start. The restriction sounds like it's partial...allowing enough fuel to idle, but when you step on the gas and the engine calls for more fuel, it starves and stalls.

Posted by: dr914@autoatlanta.com Aug 5 2019, 07:45 AM

easy and typical, losing power to the dual relay cutting power to the pump

Posted by: SteveL Aug 5 2019, 10:04 AM

[quote name='dr914@autoatlanta.com' date='Aug 5 2019, 05:45 AM' post='2735564']
easy and typical, losing power to the dual relay cutting power to the pump

Doc - are you saying that the power lead to the relay is bad, or more likely that the relay itself is bad? I see that new relays are not exactly cheap (for a relay anyway).

Thanks

Posted by: Seattle_914 Jan 22 2022, 03:51 PM

Hi Steve,

I just picked up a 914 last summer so I'm a newbie. Took a drive today and ran into this same issue. First occurred going down a hill (thankfully). I left it in gear hoping it would jump start itself. It did restart on its own but took about 20 seconds for it to restart. Engine was plenty warm. I pulled over at the bottom of the hill and it idled fine. So I took off again and about 4 minutes later it happened while I was leaving a 4 way stop up a hill (with no shoulders). Never seems to be shoulders when you're having car problems. Anyways, I drove it home for another 20 minutes with no issues. Since this is my first Winter with this car, I had a similar issue in November but I chalked it up to not letting the car warm up properly, but I think it's this same issue I had today. Did you ever resolve your issue? I'd like to hear because I have no clue where to start. I have yet to replace the fuel filter, and knowing the previous owner, it's probably 10 or more years old. New plugs, wires, etc. The car idles great and runs very well.

Posted by: wonkipop Jan 22 2022, 04:01 PM

9 to 10 it will be fuel delivery problem.

i've got a similar thing with mine but its hot weather related.
i had to replace the original fuel pump (the original 3 port) with an inline.
(its under the engine bay location).
the inline fights for fuel in hot weather and its due to how i had to route the hoses in, combined with just enough heat radiating off engine and exhausts to cause some cavitation. goes away when its cooler weather. also only happens at the lights sitting idling when heat builds up under car, does not happen on the move.

not saying your problem is this exactly, but i'll bet its fighting for fuel.
and something is causing it along the fuel line track to the pump.

there is a chance it is also the power to pump cutting out randomly as suggested above.

i've rebuilt my original fuel pump and will be reinstalling it to get rid of the fuel line that loops just that little bit too tight to get it into the inlet side of pump. also going to shield the metal fuel lines i did to replace the original plastic ones where they exit the tunnel and travel across to the fuel pump as i think this is part of the problem but not all of the problem.

hope that helps you.

Posted by: Seattle_914 Jan 22 2022, 04:24 PM

Thank you wonkipop for the lightning fast response. First step will be to remove the gas tank and replace the fuel filter. Then look at getting new fuel pump or scoping out wiring in that area. Appreciate the input.

Posted by: wonkipop Jan 22 2022, 04:45 PM

i'd check the filter on the feed side of pump first.
its a bit of a classic for a blockage to build up in that then float off once the pump stops.

where is the pump in yours.
if it is pre 75 and under the engine bay is it still an original pump (ie the old three ports with all the ports at one end)?
i think that inline pumps (like all modern fuel pumps) and those that were installed in 75 up the front (early inline) are just a tiny bit more prone to cavitation than the old 3 port roller cell pumps. not a problem if the pump is up the front. those old pumps were good in the engine bay location (particularly where they moved it to in 74 just a bit further away from the heat sources in engine bay area) but most of them wore out long ago. however there are still some on lower mileage cars. those pumps were built to military grade spec.

my three port was leaking fuel everywhere after a long lay up.
i had take it off. but it still ran.
so i rebuilt it. it turned out to be not that hard to do.
a bit tricky. once you open them up you can see how much wear there is on the electric motor brushes and armature. mine was barely worn so worth the rebuild to put all new seals into it. i'm hoping it means that all the curves on the fuel lines can go back to being very relaxed curves and get rid of my problem. the feed line on the new pump i installed meant a curve on the hose in that i just felt was too tight but had little choice about due to the length of the pump and having to connect the hoses at either end.
not as good a layout as original fuel pump allowed. i can hear the pump cavitating when the car is hot and the idle will start hunting. in extreme instances the engine starts to die and i have to kick the throttle and hold it at higher revs to keep it going. all fine once i am on the move.

given its summer down here i am having to put up with it again so its on my mind to get it on the hoist and get it sorted.

Posted by: 914Mels Jan 22 2022, 05:34 PM

You need to get a fuel pressure gauge to make sure you're not chasing the wrong system. Sounds like fuel but.... If you are losing fuel pressure you can discount a bunch of other things. Long time ago a customer brought in his '75 with a similar problem. Ends up the fuel lines got swapped at the tank end. a leaf was floating in the tank and would get sucked down over the unprotected return port which then shut off all the gas. As soon as the engine died the suction stopped and the leaf floated off for its next visit. No idea how long the lines were crossed but one leaf got in somehow and caused a lot of headache.

Posted by: 914werke Jan 23 2022, 11:02 AM

? ... start with some detail. MY, FI? Carbs? Engine displacement? Modded?

Posted by: willieg Jan 23 2022, 11:23 AM

I had a Volvo P1800 that had very similar issues. Turns out the fuel line in the fuel tank would suck in debris from the fuel tank and fuel flow would stop. The debris would then fall away from the intake in the fuel tank and fuel flow would resume. Once I figured out the problem, I pulled the fuel tank, cleaned the fuel tank and put the fuel tank back in. Problem solved. In my mind, your issue is a definite fuel delivery problem. Good luck. If you don’t already have stainless steel fuel lines, if you pull the fuel tank, this would be a good time to put them in.

Posted by: Seattle_914 Jan 24 2022, 01:55 PM

Thanks for the input. My 914 is a 1975 with the original fuel injection system & fuel pump in front. My guess is the filter is ancient because the previous owner didn't keep up with maintenance. Looks like I'll be taking the tank out, replacing the filter, inspecting the tank, and testing the fuel pump. See where it leads. Some other clues....happens more so when the tank is full, and at colder temps?