Stalling while driving

944Nick · 09:31 AM

A while back my 88 944S stalled while going 40 down a road and after some cranking it started again. This happened once twice more and once I clutch kicked and bump started it basically. Yesterday I put a bit of gas in the tank and this morning it took a bit of cranking to start. It made it barely past the driveway and stopped and has made some weird noises while trying to restart. Sounds like if the flywheel was stripped (which its not)
The only thing I can think it is would be the 50$ amazon fuel pump i put in a few months back.
The fuel line from the tank to the pump is a little bent so I thought it might be struggling for gas but that wouldn't explain much else
Also when I turn the key to just before cranking the tach will move a little bit up to just under 1 and then drop down every once in a while

Jfrahm · 01-18-2021, 09:31 AM

Stalling is often a typical 944 problem, the DME relay can fail intermittently.
DME Relay Information and Testing

A kinked fuel hose sounds bad though. It should still start and run but starve out under high load.

944Nick · 01-18-2021, 09:35 AM

Quote:

Originally Posted by Jfrahm

Stalling is often a typical 944 problem, the DME relay can fail intermittently.
DME Relay Information and Testing

A kinked fuel hose sounds bad though. It should still start and run but starve out under high load.

After reading that I think you may be right because i have had trouble starting while its warm

944Nick · 01-18-2021, 10:38 AM

I tested both (there was an extra in the box) DME relays and they came back 0.00 and the guide says close to 0 but between .1 and .3 so does that mean both are bad? I looked at the soldering and they both seem to be fine

Jfrahm · 01-18-2021, 03:55 PM

What are the part numbers? IMO if they are the early part they are junk. Best way I have found to troubleshoot is to see if you do not have the problem with a new one from a reputable vendor. Or the jumper wire.

Ohming with a DMM does not tell you much if they fail under load and/or heat.

GostRidr · 01-18-2021, 06:04 PM

Hey Nick,

Are you able to run through the fuel supply diagnostics on Clarks? I would want to rule out any issues with the filter. By the way, I would get a replacement hose for the pump to the tank. Mine failed sitting in the garage a couple years back. The way I found out was gasoline leaking down my driveway from INSIDE the garage!

Good luck and keep us posted!

944Nick · 01-19-2021, 12:03 PM

Quote:

Originally Posted by Jfrahm

What are the part numbers? IMO if they are the early part they are junk. Best way I have found to troubleshoot is to see if you do not have the problem with a new one from a reputable vendor. Or the jumper wire.

Ohming with a DMM does not tell you much if they fail under load and/or heat.

The part numbers of the dme relays are 993.615.227.00 and this other one not from porsche but is 89 6368 000

944Nick · 01:01 PM

Quote:

Originally Posted by GostRidr

Hey Nick,

Are you able to run through the fuel supply diagnostics on Clarks? I would want to rule out any issues with the filter. By the way, I would get a replacement hose for the pump to the tank. Mine failed sitting in the garage a couple years back. The way I found out was gasoline leaking down my driveway from INSIDE the garage!

Good luck and keep us posted!

I know its not the fuel filter because I replaced it when I replaced the pump but im following clarks garage and I've gotten to testing the computer plug and plug 18 is fine but I dont have a plug 35?

944Nick · 01-20-2021, 12:10 PM

I think it may be the fuel pump wires because everything else checks out. Where along the body do they run so I can inspect the wires?

mytrplseven · mytrplseven's Garage

When's the last time you checked the fuel strainer? Also is there a kink in the fuel hose between the tank and the fuel pump? I had that issue on my 951

944Nick · 01-21-2021, 10:51 AM

Quote:

Originally Posted by mytrplseven

When's the last time you checked the fuel strainer? Also is there a kink in the fuel hose between the tank and the fuel pump? I had that issue on my 951

I havent checked the strainer
(Because of course all this happens after I get a lot of gas)
And the line is bent but isn't kinked its been running for a while the way it is

Also probably wouldve been worth noting but right before it stopped I got like maybe slightly over half a tank of gas but also put half a bottle of octane boost in it which might have cleaned too well

GostRidr · 01-21-2021, 07:19 PM

Ugh. I don't have any experience with ANY of those sea foam, booster, cleaners as there doesn't seem to be a clear consensus. Sounds suspect here. Sticking with that point, I would think that testing for fuel at the rail would clarify. I do not know where the wiring goes but would think you can also check for power output at the pump to narrow it down. Keep us posted and good luck!

944Nick · 01-25-2021, 11:09 AM

So I think I got it
Since I have the S I think it has the updated flywheel and all that of the s2 age cars and I've been looking at this one random sensor that looks like the speed and reference ones thats cracked and the wire is exposed and literally green. Looking around I think its the sensor plug that i spent several days looking for

944Nick · 01-30-2021, 11:56 AM

Well I replaced the sensor and its still not running even when bumb started so im going to test the connector and other than that I dont know

walfreyydo · walfreyydo's Garage

Get a solid state DME relay (Its really essential that you do).

They are much much less prone to intermittent failure than the old OEM relays.
https://www.ftech9.com/new-products/993-ssr-pp

You can also "jump" your current relay to verify 100% whether its actually the relay or not (not test the relay, BYPASS it). Read the clarks garage link posted above on how to do that

944Nick · 02-03-2021, 11:19 AM

Quote:

Originally Posted by walfreyydo

Get a solid state DME relay (Its really essential that you do).

They are much much less prone to intermittent failure than the old OEM relays.
https://www.ftech9.com/new-products/993-ssr-pp

You can also "jump" your current relay to verify 100% whether its actually the relay or not (not test the relay, BYPASS it). Read the clarks garage link posted above on how to do that

Its not the relay, I tried the bypass before but ill try it again because maybe I did it wrong

PHillary · PHillary's Garage

Also check fuse #34 "sneaky little bastard" its to the fuel pump if it goes you don't go! Lol!