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Ron
Ron, ASE Certified Technician
Category: Buick
Satisfied Customers: 33439
Experience:  34 years as a Tech
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Buick roadmaster: I have a 1994 buick roadmasterit will start

Customer Question

I have a 1994 buick roadmaster
it will start right up and sometimes it will run and run. other times it will die within minutes annd then It wont' start up again
Submitted: 1 year ago.
Category: Buick
Expert:  Ron replied 1 year ago.
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
In order for the engine to start and stay running you need good spark to the spark plugs, proper fuel pressure (13 to 14 PSI) and injector pulse. If you can check each one of these when the engine will not start and post back with which one you are lacking I will help you determine the cause. Be sure to change the fuel filter before you read the fuel pressure to be sure the pressure readings are accurate.
Customer: replied 1 year ago.
Yes, I connected my fuel pressure gauge to the MFI fuel rail
Key On, pressurized to 41psi and dropped to 34PSI in about 15 second and stayed steady, started up no problem
I then depressurize fuel line and replaced the fuel filter
Key On, pressurized to 41PSI and stayed, no drop in pressure.
Started Engine, pressure dropped to 34 PSI and remained steady for about 5 mins, then pressure started to drop, engine started to sputter and then stalled.
Key Off, waited a few minutes
Key On, No Pressure
Key Off
waited overnight and
Key On, 41 psi, no drop
started up to 34 psiI BELIEVE THE FUEL PUMP MOTOR IS TIRED. I ORDERED A NEW ONE FROM AMAZONPLEASE ADVISE
Expert:  Ron replied 1 year ago.
Providing you have a good power and ground at the new pump then if the pressure is dropping off that usually means the new pump is defective. The next time it stalls and the pressure drops, check fro power and ground at the pump with the key on and the engine cranking. If you have power and ground and no fuel pressre that means the new pump is defective.
Customer: replied 1 year ago.
So I have not replaced the pump, as far as I know the fuel pump in the tank is the original. I'm in the process of replacing the pump. the new one arrives tomorrow. tonight I'm getting the gas tank ready to drop.
I"m assuming when cold, the old pump powers up, so it is obviously getting voltage. its when the pump has been running for awhile that it seems to fail. anyway, I hope to have the new pump in over the weekend. I'll up date you then.
Expert:  Ron replied 1 year ago.
I would agree with that and I think you are on track. Let me know how it works out, sure sounds like a bad pump to me as well.

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