1994 Pontiac Grand Prix

[pattywho]

It is burning way too much fuel and slight power loss but car is still running and starting fine. It eats gas like no tomorrow. Please help any suggestions would be most appreciated!!!!

[tblake]

What motor do you have?

I would suggest to check fuel pressure key on engine off, and with the engine running. Then I would pull the vacuum line off the fuel pressure regulator and make sure the regualtor isnt leaking gas into the line.

[richtazz]

In addition to above suggestions; do you have a check engine light on (if so what codes are stored), and is the car shifting all the way into overdrive?

[pattywho]

Originally Posted by richtazz

In addition to above suggestions; do you have a check engine light on (if so what codes are stored), and is the car shifting all the way into overdrive?

Thanks very much! You have solved the probelm and we really appreciate it and very kind of you!

[pattywho]

Originally Posted by tblake

What motor do you have?

I would suggest to check fuel pressure key on engine off, and with the engine running. Then I would pull the vacuum line off the fuel pressure regulator and make sure the regualtor isnt leaking gas into the line.

Thank you very kindly for your info. We did replace the gas regulator pressure valve but it ended up being a computer chip, mainly the map light chip. Car is functioning normally at this time. Thanks again for your info and have a great day!

[pattywho]

Okay we took it for a test ride after changing all of these things and it is still sucking gas like crazy. Could it be the fuel pump? We have also done a tune up on it. It is running better but still sucking fuel like crazy. Any other suggestions would be most appreciated.

[tblake]

What motor do you have? As Rich asked, is the SES light on?

Next step I would ohm out the injectors to check for any that are shorted.

[pattywho]

Originally Posted by tblake

What motor do you have? As Rich asked, is the SES light on?

Next step I would ohm out the injectors to check for any that are shorted.

Sorry for the delay in reply. It is a 3.1 liter engine. How do you ohm out the injectors?

Thx again for your help.

[tblake]

in 94 did it have the 3100sfi motor, or the 3.1mpfi?

I know on the 3100sfi there is a large electrical connector in the alternator area, you may be able to unplug it, and text the resistance of the injectors there.

You could also rent a fuel pressure tester from advance or oreilley's or autozone and check fuel pressure.

[pattywho]

Originally Posted by tblake

in 94 did it have the 3100sfi motor, or the 3.1mpfi?

I know on the 3100sfi there is a large electrical connector in the alternator area, you may be able to unplug it, and text the resistance of the injectors there.

You could also rent a fuel pressure tester from advance or oreilley's or autozone and check fuel pressure.

Thank you for your information. We agree with you that it is definitely one of the injectors. My question is, if we pull them out of a used car to replace them, would that be in our best interest as they are very expensive up here ($120/injector). Also would there be any visual evidence by looking at the injector as to why it has failed. We have never dealt with this type of problem before but can do most other things on a vehicle. Again, we thank you for your advice and would appreciate a further reply.

[tblake]

there is generally two ways to chech injectors.

1) injector balance test (requires a spendy balance tester and fuel pressure guage)
2) ohm check them

Have you looked for that large connector I told you about? You either have to find that and check them there, or remove the upper intake plenum.

I will see if I can find a wiring diagram so you know what wires to ohm check at that plug.

[rkvons]

Originally Posted by pattywho

Thank you for your information. We agree with you that it is definitely one of the injectors. My question is, if we pull them out of a used car to replace them, would that be in our best interest as they are very expensive up here ($120/injector). Also would there be any visual evidence by looking at the injector as to why it has failed. We have never dealt with this type of problem before but can do most other things on a vehicle. Again, we thank you for your advice and would appreciate a further reply.

Why do you agree that it is one of the injectors? You say it is sucking gas like crazy. Did you fill it, run it to empty and calculate the mileage? What kind of mileage is it getting?

[tblake]

good thought rkvons. Even though its "sucking" gas doesnt mean that the motor is to blame. It could have a trans issues, or maybe the tires are extremely under-inflated.

[richtazz]

To the OP:

Please reread all the posts in this thread and answer those questions in which you haven't. In particular, do you feel the car shift through all 4 gears as you accelerate
? We cannot help you if don't answer our questions, and we could continue speculating until the cows come home.