1988 924s

Hey all, I have been an avid rennlist reader for over a year now . Today I finnaly decided to create my own membership because I am in dire need for some advice from other Porsche 924s and 944 enthusis. After much restoration and a years worth of driving my 60,000 mile Porsche. 924s will not start And it has me scared and driving me crazy. So here is what I have checked so far. Any tips , things to look at , or clues will be greatly appreciated. .
.Car starts right up on starter fluid so I believe this is pointing at a fuel delivery issue
. Changed in tank fuel strainer because original one was completely destroyed. Also changed in line fuel filter.
.Checked fuel pressure at rail and have about 36-40 psi when cranking and d.m.e. relay jumped
. Noid light shows I good signal at injector harnesses
. Resistance on injectors is in proper spec
. jumping d.m.e. relay did cause fuel pump to run constantly.
. I do have good tach bounce! Does this mean speed and reference sensors are working properly
. checked for spark at all 4 plugs with a spark checker light and all four wires showed proper signal.
. Changed year old sparks for the hell of it and properly gaped them
. cleaned throttle body
.changed air filter
. pulled fuel injectors and found two to be leaking.. The appeared very fouled . rust was present inside them.
. When I first got the car the tank had tons of rust and varnish at the bottom. Toughly flushed , cleaned , and sealed tank.

Everything is pointing to the injectors as the culprit and before the car would not start I was noticing the car to be sputtering and hesitating and running slightly rich. I went ahead and ordered some remanafactured injectors from autozone and i am hoping this will solve the problem! Any advice? Thanks a bunch !!

1988 924s

I also had all belts replaced last year!

jhowell371

From the sounds of your post it sounds like it starts on starting fluid and continues to run, correct? Try checking the fuel injection temp sensor. I think that what it's called(it's late and I'm old and too tired to look it up). It causes the fuel injectors to add fuel to compensate for the cold engine. It's in the front of head, driver's side, below the intake. Been there done that. Clark's Garage has the simple test procedure.

1988 924s

Thanks for the quick reply! It will start right up when starter fluid is sprayed directly into throttle body or air box. It will only run for a brief 6 second period then dies when the ether runs out. I assume it would continue to to keep running if kept giving it spray but the use of ether scares me due to many starter fluid horror stories ! I have deffinatly target the dme temp sensor like you suspect is a likely culprit! I plan in just ordering a new sensor tommrow since it is original and they cheep to replace. Just ready to get back in this thing ! I love to drive it! Thanks for the help! I suspect it is the injectors!

944crazy

So have you swapped in the new injectors yet?

Tom M'Guinn

Since it runs on starter fluid, you can assume away many potential issues (spark, timing, speed/ref sensors, compression, etc.). Assuming your gas is good with no water in it etc., then I'd start by physically confirming the injectors are spraying fuel when you crank the motor. You can pull the plugs and just look/smell in the cylinders -- if there's fuel, you will know. If no fuel, then check injector connectors (under the boots), as one bad wire can prevent them all from firing. A bad DME itself could also stop them from firing. Assuming there is fuel, then chances are good that you are just too lean or too rich to fire up. Have you looked for big vacuum leaks? If you are sure there are none, then I'd check the air-flow meter signal and the dme temp sensor to start, and check the DME for solder joint cracks.

1988 924s

Hello all! I have not installed the new fuel injectors. They will arrive for delivery at my local auto zone in the New Orleans area. Well glad it is safe to be able to rule out a lot from the car " catching on the starter fluid. I did visibly inspect the fuel injectors and they don't look good. They had rust coming out the ends , and two were visibally leaking from the bottom , not the o rings. I did not crank the motor while watching their spray pattern but from the looks of them they can be to good. My theory right now is that they got very fouled and dirty from when I was driving for a year with a rusted , sediment filled gas tank. A month ago I decides that it was time to do the tank the right way and clean and seal it properly. I installed the clean tank, changed the fuel filter , and tank strainer added some seafoam and ten gallons of chevron gas 93 octane and started it right up. Car ran for 30 mins or so very rough, and was hesitating on accerlation pretty badly. Then all of a sudden it would not start at all. Please keep the ideas coming I do appreciate it. I want to be able to correct this issue fast so I can get back to fixing up the cars interior such as adding new carpet, and a new stearing wheel

1988 924s

So I must add this .. I got off work and decided to investigate . Turned the key and the car started for a second or two then died. This was the first crank of the day and this was with no starting fluid. I tried to start it one more time and no rumble.. Just kept cranking. I then jumped the three terminals again so I could try to start it like that hoping for a miracle and it just cranked away. While I had the relay jumped I listened around the motor and herd a hissing noise that deff sounded like an air leak. I felt around the damper and could feel a slight feeling of cold air?. Could the damper itself be busted and leaking and could this cause a no start?

Jfrahm

If the damper was leaking fuel into the vacuum line the engine would have wet plugs and not start on starting fluid. You'd also see fuel drip out of it with the vacuum line removed.

With the DME relay jumpered you will get fuel passing through the fuel rail and back to the tank so the fuel rail might get cool (or warm) that'd depend on the weather. If the fuel rail was warmer than the gas in the tank then the rail would cool down when gas was circulated though it.