rwdfan

In the morning it is all but impossible to start my car without it nearly dying for the first 2 minutes, I usually end up killing it three times before getting it out of the garage and into the alleyway where I live. You can tell its running rich. Plus for about the first mile its bogging a bit. I believe the 255 Walbro in it is too much pump, I thought that the engine computer would only send so much fuel...So...I'm confused. The car had a supercharged engine in it before, but now its near stock for now. What do I do? If I purchase a tuner, can I turn down the amount of fuel being sent? Or would I have to install a fuel regulator...thought they already had one. Or just replace the fuel pump until I add more power later? By the way, its not a spark issue, car has new plugs, cap, rotor, wires, timing is set to 10.

1990NOS!

have you checked your fuel pressure? Since you say its nearly stock... should be no more then 41psi and thats rich.Factory psi is 39.
Do you have a FPG (fuel pres guage) mounted under the hood closest to the FPR and fuel rails?

Stepman

I wouldn't think it is a pump problem but, more of a coolant sensor issue since, it clears up once it gets warmed up? How can you tell it's running rich? Black smoke?

rwdfan

I can tell by the way it runs, it bogs like it is receiving too much fuel. It only does this when cold or cool and the engine is just started or not up to operating temperature yet. Plus, you can smell a gas like smell in the exhaust. Its not quite gas. I know its not any other issue because it runs fine after it gets two minutes to warm up. If it is warm outside the engine will be just warm enough for the fuel to atomize properly. But I still think it is a little too rich. I do not have a fuel pressure gauge on the car as far as I know. I will have to check on that. What would make you think it is a coolant sensor issue. That should not have any effect on how the car runs...That just sends the signal to the dash on how hot the coolant is. Right? The only thing that dictates the flow of coolant as the thermostat. Even then, coolant should not have anything to do with how the car runs in the first 60 seconds of it being started. You can run a car without coolant for that long because its nowhere near operating temperature yet.

1991LX5.0

i dont understand the first post. Was this happening before the 255 was installed or did this start after. Also was the 255 in it when it was supercharged and now the motor is near stock and your having the problem? If the car was supercharged and you went back to stock that sounds about right becuase if the car was tuned with the blower they would have added lots of fuel to account for all the air being crammed in there which would make you run very rich if you took the blower off

rwdfan

Ok. Heres what happened. I bought the car with the 255 in it. It was supercharged when it had the 255, it has been having this problem since it has been cold. Thing is, you say tuned. The chip that had the custom program was taken out when the supercharged engine was taken out and sold. So, I am now having this with the near stock engine and the 255. But only in the cold or when its cool.

1991LX5.0

what size injectors are on there now and do you know if the MAF is calibrated for those injectors?

rwdfan

The engine is stock except for a cold air intake. Injectors and MAF should be stock. Its not the original engine.

Stepman

I'm still thinking a coolant sensor because that is what computer uses to calculate fuel, If it says -40 it's going to dump it. The pump shouldn't matter because no matter how much the pump is capable of, it is controlled by the regulator. I suppose it could also be an idle control motor, if it doesn't allow enough air. Of course if the comp see's -40, it could be shutting down the motor but, I would think it would try to raise the idle in that case,so, mabe its just the idle motor. (just thinking out loud now).....but it really don't sound like the pump....did you get a gauge yet?

rwdfan

I thought it was the MAF sensor that calculated fuel. It calculates it by the temperature of the incoming air. It will not be until after work today or tomorrow before I can even try to test the fuel pressure with a gauge. Is there an easier way to test the fuel pressure?I amnot used to working on fuel systems.Plus, I am not exactly made of money this month. It might have to wait until next month. I am in the process of starting my own business.