I was driving home when she started to sputter, then when I pressed the gas it dropped and I was hard pressed to get 15 mph out of her. I finally got to a safe place where I could stop. I let her rest a bit and I was able to re-start. She was fine again for a little bit, when the symptoms came back. I was barely able to get her home. Now she will not stay started. She turns over and acts normal for a second and then shuts off.
My first thought was the fuel relay DME. Got a new one and replaced, no change.
Next I pulled the fuel filter and found it was the original dated 4/14/1989.
I've decided to go ahead and replace the pump as well while I have everything apart.

Any other suggestions? What else should I go ahead and change while I'm at it?

Thanks in advance, Chris

 

What kind of fuel pressure do you have? Consider the possibility of a failing/now failed fuel pump.

 

A number of things: What brand of DME relay did you install? If it was a Uro brand, toss it and get a different brand. Second, check the fuel lines for collapsing when squeezed. Pull the vacuum line from the fuel pressure regulator and see if you can smell gasoline in it. Also start the engine and see if there's vacuum on the line to the FPR. Check to see if you have tach bounce when turning the engine over. It's barely noticeable but if it's not there, suspect the Ref/Speed sensors (also check the connectors for the TPS, AFM and the ref/speed sensors (rear of the intake manifold in a bracket near the oil filler cap). Good luck.

 

Your symptoms don't necessarily point to any one culprit, and indeed could be a wide number of things. If it were my car, I'd start by checking for spark, checking fuel pressure, and checking the fuel injection pulses with a test light. If you're car won't run, chances are one or more of those will be bad and you can then start narrowing down with more specific tests. If they all test good, then you're probably getting a bad sensor signal somewhere or have big vacuum leaks, causing the fuel-mixture to be too far off to run. Either way, some basic diagnostic info goes a long (long) way when trying to fix something like this. If you've already done some diagnostics like that, then post up the results as they may help us steer you in the right direction.

 

I just had this happen to my other car. Vehicle would start and idle but no power when you try to accelerate. It ended up being the fuel filter. I would try replacing the filter first.

 

I was not able to run many tests because the car would not remain running for more than a half second.
I am currently in the process of changing out the fuel filter and fuel pump, now. Was thinking about replacing the vac lines with silicone ones while I was at it.

Anything else while I'm changing things out?

 

If the car starts up then dies immediately, that can be a sign of a bad AFM signal, so you might check that. The car doesn't need to run to check for spark and fuel though -- in fact it's easier to test both when just cranking with the starter motor, but I won't preach... Just re-read and see you have a 27 year old fuel filter, so whether or not that's the issue, you probably got your money's worth out of that one.

 

Ok so I'm a bit of a novice when it comes to Porsche, but I want to learn! So can you walk me through testing for a bad AFM signal?

 

Well, a quick and dirty test for your purpose is just to test the voltage at pin 7 of the DME when you start up the car. Should be somewhere in the .5 to .9vdc range. If you don't have a good digital multimeter, it's almost required equipment for 944 ownership. Tons of youtube videos that can help you learn to use them too. For a complete test of the AFM, and everything you wanted to know about it (and the rest of the car) check out clark's garage. Here's the specific page on the AFM:


http://www.clarks-garage.com/shop-manual/elect-22.htm

 

Could even be as simple as the hoses after the AFM has come loose and you've got a massive leak. The J-boot loves to crack underneath where you can't see it.

 

Well, Monday I completed the install of the new fuel pump and she can back to life. I then went ahead and changed to new silicone vacuum lines. I also added a new solid state DME relay.
She runs and sounds better than ever.
Hopefully no more fuel issues!
Thanks for all the help and suggestions!