Just got my 850 GLT 1993 back from dealer with a new fuel pressure regulator. Before I took it in, the cylinders were almost full of gasoline and a whole lot was in the intake manifold. How did the gas get into the cylinders without the injectors being open?

I imagine that if the regulator is leaking, that it just wont hold the pressure and the gas will just flow down the return line back into the tank.

While I was trying to figure it out I checked the fuel pressure and it went up where it needed to be . I can see that I didn't keep the gauge on long enough to find that it was leaking, but I was looking for something that was keeping the injectors open-something that was telling the ECM to go full rich- like during a cold start up.

I checked a few different sensors but I still don't understand how the fuel pressure regulator leaking would cause what it did.

Can anyone explain this to me please so i can stop pulling my hair out after spending $715.
Its killing me that I over looked this especially because the parts total for my bill (new spark plugs, regulator, oil & filter) cost $200 and the rest was labor that I have the tools for and am capable of doing.

Thanks in advance for any advice!

Revdevil

 

Can't you take it back to the dealer and complain? That sounds incredibly dangerous...

 

When the regulator goes bad it will leak through the vaccum line back into the intake manifold.
Does your regulator have a vaccum line?

Are you sure the injectors aren't leaking?

 

Revdevil,

Did you ever find a fix for this problem? I've got an 850 (1995, normally aspirated, 5 speed manual transmission) that stalled on me a month ago and has been in the shop ever since. It flooded out at a stoplight and never came back. My mechanic is stumped; he's replaced the fuel regulator (it was bad--fuel was in the vacuum line), but it's still flooding. He claims a Knoxville, TN dealer has one that's doing the same thing after $3000 worth of work, which has resulted in a consultation with Volvo engineers; we're still waiting for their verdict.

I'm trying to get my car back (I'm a commuting student, and have been borrowing a car for 3.5 weeks) but it of course doesn't run for very long. This is the first major problem I've had with it.

 

Are the injectors leaking?
Is the coolant temp sensor good?

 

The verdict from my mechanic is as follows, to the best of my understanding:

(1) The fuel regulator was bad (same scenario as Rev--excess fuel in cylinders and intake manifold). Replacement of fuel regulator fixed problem with fuel in intake manifold, but still receiving too much fuel in cylinders. He feels that the fuel regulator being bad was a separate problem that only came to light when a secondary electrical problem developed. This has been replaced (I've seen it).

(2) Injectors are physically OK.

(3) Coolant temperature sensor is functioning normally.

The mechanic suspects that one of the ground wires has broken, and the result is an electronic glitch that's keeping the fuel going in at maximum. He is supposed to check those in the morning. Of course, in the meantime, he had a WONDERFUL 940 turbo he was trying to sell me...I was tempted until I saw where the front of the engine compartment had been hammered out from a collision...

 

If a ground wire was Broke then the car wouldn't run or only run on a few cylinders.
The Computer sends a Ground Pulse that fires the injectors.
Did he Pull the Fuel rail out and watch the Spray of them and then let them sit to see if they are leaking?

If there is an electrical problem with the injectors there should be a codes for it in the computer.

 

Yes, I think the fuel rail has been pulled out of it several times. The way it was described to me, the fault codes in the computer tell him yes there's something wrong, but doesn't narrow the problem down. He talked as if the fault code that's displayed indicates a bad computer unit, but he says if there is a problem in the grounds, that will return the same code for a faulty CPU when in fact there is not a problem with the CPU, but in the grounds themselves. He claims (and my Haynes manual seems to back this up) that if the car were a 96 instead of a 95, the electronic diagnosis ability would be greatly enhanced.

The folks he has consulted claim to be experiencing the same problem in another Volvo, and a computer replacement didn't do the trick.

I should add that while he can get the motor to fire, it doesn't run very long before it floods itself again. I don't know if all or only some of the cylinders are firing.

 

Have him crank it with a Noid light in the Injector plugs. If the light blinks then they are working normally.
If it doesn't flash it is a ground problem. If it stays lit then again a ground problem.

 

Tech,

Thanks for the advice. My mech. seems to have isolated the problem--bad ground to the second cylinder to the left from the right-hand side of the motor, if you are standing in front of the vehicle facing it. He seems to think that what caused the ground going bad is the action of the motor when it is started--apparently, the direction the motor pulls in (I've always notices that motor seemed to move a lot when cranked!) pulls a portion of the wiring harness very tight. He believes he can replace this ground and move some of the wiring a bit to give it more slack when cranking. I'm supposed to get it back tomorrow afternoon, provided no other distractions or disasters occurred. I think he isolated the problem ground by wiggling individual grounds around until he found the one that fixed the problem cylinder.

Adam Stewart

 

Sounds good keep me posted.

 

Any news on this prob? Just curious...