Like it says, car I just bought used to have a powerdyne 6 psi unit on it, and right now it still has a FMU and an inline pump still on it. When under load it stumbles, then revs clean, then stumbles and pops. According to the A/F gauge, anything over 1/4 throttle, and it goes to super rich. Could this be the stumbling problem? I checked everything else, EXCEPT the opti which is the last straw....thanks

 

I doubt it's the pumps. The only way it could be is if the FP were rising for some reason. It possible to have too much pump for the regulator or the return line to handle and have excess FP. But this would not be rpm related, in fact it would be worst at idle. The regulator, assuming it's working right, should open up and keep the FP at the correct level.

Since the car had a blower, has the PCM been reprogrammed? It could be reprogrammed to add fuel.

Rich Krause

 

That is the thing, its running on the stock program right now. Another reason why I believe its possibly the opti is because it will not start at all, after you crank, let off, then crank, it will fire, and you have to hold the gas about 1/4 for a minute for it to hold an idle, otherwise it will die, and not start back up. Sounds as if its running on 6 cyl instead of 8. It has the original non vented opti with 140k on it, so maybe that is the entire problem....what do ya think? I appreciate the input...thanks

 

A friend had a problem kinda like that...turned out being the computer ground on the firewall supposedly.

Joe

 

I see no reason the FMU should affect things but just for sanity sake I would remove the FMU from the system (hook fuel lines back up like stock). You may also have a problem with the fuel regulator. You need to get a fuel pressure gauge on the car ( a mechanics gauge would work for checking things) and see what the fuel pressure is doing.

Later ... Larry S.

 

Hmm, I think I found some of the problem. I lifted the hood at night while it was running, and the coil was arcing badly off the wire, and one of the plug wires was lighting up the passenger side! Maybe this is the problem