TurboMike

i've got a 83 944 NA that has a SERIOUS cold start problem. When you start it the car absolutely floods to death. Sometimes if it stalls, it won't restart back because it's flooded so bad. We've replaced EVERY ( i really mean every) sensor on it and just replaced the DME and AFM... same problem. New Fuel pump, pressure reg, etc. The way i can get it to clear up is by unpluging one injector at a time and it'll clear up then run great. Warm restarts are fine. ANY ideas at all?? I'm truly stumped.

Zero10

Check out your fuel pressure. It could be leaky injectors as well.

I know you changed the pressure regulator, but remember, it is vacuum operated, so if there is no vacuum, it will be up about 10psi (give or take), so it could be a vacuum leak on the way to the FPR.

Those are my guesses.
If it didn't help, at least now your thread is at the top of the list =)

special tool

MSD 6AL and blaster2 - and keep the plugs clean in winter.
(AL because it comes with a 3000 RPM valet/wiseass son chip)

TurboMike

I checked that very thing last night and discovered that the two hoses on the throttle body were reversed. The one going to the FP regulator didn't have vacuum on it. It has been this way for a long time because i marked the hoses when i took them off before. So i fixed that, changed the oil (it had a slight fuel smell to it) and a fresh set of plugs. I started it this morning and it did fine. i'll try again tonight. it's in the low teens here so the cold start problem can easily be tested. Surely the regulator hose could have caused it to run THAT rich?

Charlotte944

Yes it could.

Normally vacuum to the FPR is some where between 14" and 18" Hg which gives a fuel pressure of around 30 psi. The FPR is designed to open with vacuum. The FPR controls fuel pressure by regulating how much fuel is recirculated back to the fuel tank.

With the throttle body vacuum lines reversed, there is NO vacuum going to the FPR which gives a fuel pressure around 50 psi.

Zero10

Well, yes and no.
See the FPR is vacuum dependant, it is set to run say... 40psi above the pressure on the other side of the diaphram (SP?), so, if the vacuum is disconnected, and it is idling, where you should have 18"Hg vacuum, it will cause the fuel pressure to go up a decent amount. Which could cause your problems. However it could have been a combination of things, so do check if it has cured the problem.

For what it's worth,I had a small leak in the vacuum line AT the FPR, it was just a little loose, and I was only getting about 10"Hg vacuum at the FPR, and my mileage went from 12L/100km to 17L/100km (almost 50% worse!).
So, never underestimate the FPR, but see if it's fixed the problem.

RMills944

Would something like this cause the car to turn many times before actually cranking also? My car has been like that for about 2 years now and I can't find the problem. Maybe it's leaky injectors, a vaccuum problem, or soemthing of that nature...

Zero10

How many times does it turn? Mine turns 6 times every single time I start it, and I've been told that's normal.

Cass944

My car turns like 2 times. Sometimes it only does like half a turn. Its almost instant. Is that werid?

adie

I think there's a fuel pressure retaining mechanism somewhere near the rear of teh car, I'm not sure of the reliability of these, I guess the pressure either losses it'self via the diaphram or possibly into the engine via leaky injectors, either way I thint that it takes a few seconds for teh car to build up enough pressure to satisfy the senders, if mine doesnt start on teh first couple of rotations I turn off and then it usually restarts 1st click.

Zero10

Mine only ever started once on 1 turn, other than that it's always 6, and that sort of bugs me.
There is a check valve near the rear of the car, but there is nothing fuel pressure related back there other than the check valve. If your car is working perfectly, it is my understanding that the rail will hold pressure for many hours. However if it holds less than 18psi after 20 mins, you have a leak somewhere. I know mine will hold 35psi for about 2 days, after that I decided it was good enough.
The fuel pump in our cars is pretty powerful, and it will pressurize the rail very quickly, even when mine was completely empty, it only turned over 8 times before it started. If it is full, just not under pressure, it should be pressurized within 1 or 2 rotations of the engine.

adie, I am not sure what you mean when you say 'to satisfy the senders', to the best of my knowledge, the DME hasn't got the foggiest idea what the fuel pressure is, there are no sensors that I have seen.

I think the source of my '6 turns' problem is my injector spray problem, and VERY low compression (~110psi on all 4).

jason952

swap dme relay?