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AutoTech1, ASE Certified Technician
Category: Car
Satisfied Customers: 42
Experience:  16 years experience, ASE advanced level cerification, Emission expert, Repair shop owner
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1998 oldsmobile silhouette: my fuel..blowing fuel..intake manifold

Customer Question

1998 oldsmobile silhouette Problem my fuel injection has gone crazy!!!! It is blowing fuel out of the bottom of the the fuel regulator and out of the top of the PCV vacuum line that plugs into the the upper intake manifold. What the heck is the problem???????? Ineed a 3400 SFI expert please. THX
Submitted: 7 years ago.
Category: Car
Expert:  AutoTech1 replied 7 years ago.
You seem to have made a good diagnosis of the problem with the fuel pressure regulator, have you tried to run the car with the vacuum hose unhooked from the regulator to see if fuel is still leaking from it? If not you may want to try this, it is ok to do at idle for a few minutes, look for leaking o-rings all around the fuel rail and at the regulator. The only way it could really get in the upper intake plenum where the pcv hose connects, would be though the vacuum line hooked to the fuel pressure regulator. You may also want to check for any computer codes. Just because the regulator is new does not mean it can't be bad. It is also very easy to roll the orings used on the pressure regulator when installing it, check that.

Edited by AutoTech1 on 2/19/2010 at 3:45 AM EST
Customer: replied 7 years ago.

Tried a new MAP sensor also .. Your not understanding it's not just a leak it is under pressure and blowing out every where, it's like it gets to the regulator then stops but the fuel rail is clear and not clogged in any way.....When I say blowing out every were I mean from the bottom of the regulator from the seal that goes into the feul rail plus out the vacuum from the PCV line pops it right out and sprays 3 feet in the air... HELP

It does it just by turning the ignition on also... seals are all good...It seems like it is getting to much feul to handle at idle (that is when it starts) but usally it will not start becuase all the feul is being blown out from regulator and upper plenum manifold..

Customer: replied 7 years ago.

Still waiting on a answer? It is not the pressure regulator or the o-rings I checked that before I asked the ? This all happened when I got done with changing the intake gaskets if that helps


Expert:  AutoTech1 replied 7 years ago.

does the fuel spray out with the key in the on position, or only when the car is running?

Customer: replied 7 years ago.
With the key on also. Did you see that I changed my intake gaskets? Yes it sprays fuel with just the key on also?????
Expert:  AutoTech1 replied 7 years ago.

The fuel enters the rail on the rear side at near 60psi, it gets as far as the regulator, and provided all the 8 o-rings that have pressure on them at that point are sealed, none of the injectors are stuck open, the regulator is in place and functioning, and there is no cracks on the injectors or rail, that pressure is held in the rail until vacuum from the running engine opens the regulator and fuel is transfered back to the fuel tank. If any leaks are present the fuel will spray out with tremendous force and may appear to be a huge leak, when in reality it is quite small, it could be leaking from the tops of the injectors at the o-rings, through the regulator, or the regulator o-rings, or even the quick connectors at the end of the fuel lines where they hook to the rail.

Customer: replied 7 years ago.

I'm going to give you your 23.00 dollars but ther are still ?s I need to ask, I have it tore down and the fuel rail off of it at the moment tomorrow morning i'm going to put it back together. I will be in touch with you after that prob ask you a couple more ?s then I'll pay you. Your telling me things that are not happening it's not leaking any were except were I said. But I'll put it back together tomorrow and tell you again were and what is leaking.

Thank You for your response but not done yet. Would a couple of clogged injectors cause that much pressure leaking?

Expert:  AutoTech1 replied 7 years ago.

Clogged injectors could in no way cause the situation you have described.

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Customer: replied 7 years ago.
Auto Tech1 were are you?