Hello,
I have a 1984 Porsche 944, I purchased it about 2 weeks ago with a low fuel pressure issue. The car supposedly just needed a fuel filter, I replaced the fuel filter and pump, I think I saw the fuel pressure shoot up to around 4 bar (58 psi). I then tried to start the car and it wouldn't start, I put the injectors in a cup and fired them and only 2 sprayed, I replaced the injectors and did the same cup test and all 4 fired. I tried to start the car and it puffed and would get close to idling then it would die. I also had someone look at the top of the AFM to see if the thing was moving (I'm unsure of the technical term) and they said it wasn't moving while I was cranking and giving the car throttle. Spark is good, DME is good and the tach bounces. I'm unsure of where to go because I haven't seen any threads with my issue before.If anyone has any advice it is much appreciated.

Thank you,
TurrFinn

 

Vacuum leak is the first thing I would check
https://www.clarks-garage.com/shop-manual/ts-01.htm

 

Does it run if you give it a lot of throttle? That would fit a vacuum leak.

Are you sure the spark plug wires aren't mixed up? Easy to do and might cause this condition

 

Remove AFM and rotate "barn door" internal flapper. Judge how it rotates. Check Clark's Garage website for test procedure

 

I looked at all the vacuum lines today and didn't find any leaks, once it warms up I'll take a look at the AFM according to Clark's Garage

Edit: I took a quick look at the AFM, the conducting strip looks lightly grooved to the point you can't feel the groove. I also moved the arm at the top of the AFM that opens and closes the barn door and at the start of opening it, it felt sticky then it would swing smoothly. I'm having a problem with air I could only presume there's something wrong with the AFM let me hear yall's thoughts.

 

Remove the AFM from the intake air circuit and try to start the engine. Observe what happens????

 

I cleaned the AFM and it make the barn door less sticky. When cranking the car I notice the arm on top of the AFM doesn't move when giving it throttle. Is there any chance the car would have a bad TPS or are there any signs are ways to diagnose it? I'll try to start it without the AFM this time or have it help open and unplugged since its already back in the car.

 

Test DME coolant temp sensor per Clark's Garage. The fuel mixture might be lean when it should be richer on cold start.

 

The car has a chip tune from the 80s according to the previous owner and the car would run extremely rich on the power tune vs the stock tune. On crank I can also smell the fuel that ends up in the exhaust from inside the car, I doubt the temp sensor is bad but I'll still check tomorrow. I'll keep the thread posted on what I find.

Edit: The DME/ECU has a switch where one side says power and one side says stock, I currently have it set to stock.

 

New update for the the thread. I tested my AFM according to Clark's Garage and the air temperature sensor read 0 ohms, key out of the ignition and key turned to accessories. Clark's Garage states "With air temperature between 15 - 30 °C, the ohmmeter should read 1.45 - 3.3 k-ohms". My OAT is 18.88 °C (66 °F).

 

Today I replaced the starter because it was just clicking and the AFM. I tested the new AFM and it actually read between 3 or 4 ohms. I also got a new batter since the battery was old battery was bad. I went to start the car and it will start idling for a second then die, i bumped up the idle screw to see if it would do anything and no results other than a higher rpm idle for that one second. Could the ECU/DME have a bad solder joint? (I currently have brand new FTech9 DME relay in the car so I know it works)

 

Will it start and run with carb cleaner sprayed into the intake? 58 lbs is too high a rail pressure. Should be about 25 psi. Since you smell fuel, sounds like your pressure regulator might. Be kaput. If you have a hand held vacuum pump, hook it up to the regulator and see if it holds vacuum. If not… you know what to change next.

 

The spec in my Haynes Repair Manual is "between 33 and 39 psi." It then goes on to say pressure above 58 is possibly a faulty FPR. The fuel pressure blew the line off a barbed fitting and I saw it hit 4 around 4 bar. I haven't check the FPR but it is shiny new and the previous owner says that he replaced it less the a year ago. I just pulled my DME and am checking for bad solder joints, If I don't find anything I will retry a fuel pressure test tomorrow. I will keep the thread posted on what I find.

Edit: I tried to start it on Brakleen (The Flammable kind) and it puffed the same way it normally does.

 

I pulled apart the DME and found corrosion. I don't know if this enough for me to have a problem, looking for some input.

 

Looks like you have waay more than corrosion problems sadly 😥 something got really hot next to that chip!!