91 Grand AM LE 2.5l Doesn't Run Right When...

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Old 07-10-06, 12:18 PM
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91 Grand AM LE 2.5l Doesn't Run Right When...

91 Grand AM LE 2.5l Doesn't Run Right When the fuel pump relay is pluged in but when it isnt pluged in it runs great and for a long time.

What do you guys/girls thin could be the problem.
 
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Old 07-10-06, 12:28 PM
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Originally Posted by chevyastro4x4
91 Grand AM LE 2.5l Doesn't Run Right When the fuel pump relay is pluged in but when it isnt pluged in it runs great and for a long time.
It shouldn't run when the relay isn't plugged in. Are you jumpering it
 
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Old 07-10-06, 01:37 PM
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no, it is running without the relay. after i pulled the relay the pump doesnt turn on
 
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Old 07-10-06, 01:41 PM
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The the wiring to the fuel pump is shorted some where. or wait hang gm product that means that there is an alternate means to power the fuel pump.

Geez its been a long time. oil pressure switch I believe is the alternate way the pump gets power in case the relay fails. disconnect the oil pressure switch and with the relay out and tell me if you can start it.

Thats why you can start it with out the relay. you could have some bad wiring in the relay circuit or bad contacts
 
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Old 07-10-06, 01:46 PM
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Originally Posted by chevyastro4x4
no, it is running without the relay. after i pulled the relay the pump doesnt turn on
also reread this, your unclear

If I am reading this correctly you are running the car then pull the relay, but if you try to start it the pump won't come on.

the engine needs to build oil pressure before the oil pressure switch will close.
 
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Old 07-10-06, 06:16 PM
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Originally Posted by snuckers99
The the wiring to the fuel pump is shorted some where. or wait hang gm product that means that there is an alternate means to power the fuel pump.

Geez its been a long time. oil pressure switch I believe is the alternate way the pump gets power in case the relay fails. disconnect the oil pressure switch and with the relay out and tell me if you can start it.

Thats why you can start it with out the relay. you could have some bad wiring in the relay circuit or bad contacts


still starts there isn't any power going to the pump because it isn't kicking on and i check voltage to it and theres none
 
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Old 07-10-06, 06:18 PM
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Originally Posted by snuckers99
also reread this, your unclear

If I am reading this correctly you are running the car then pull the relay, but if you try to start it the pump won't come on.

the engine needs to build oil pressure before the oil pressure switch will close.

no, when i have the relay pull out car off, then start it with the relay out it starts but if i have the relay in and try to start it, it doesn't start just backfires
 
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Old 07-10-06, 08:15 PM
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I can't see how your car will run without any power getting to the fuel pump. Will it KEEP running? Or are you just starting it for a second with the relay out...in other words, using up the fuel in the lines. A car can't run without fuel...and no battery power to the fuel pump means no gas. I'm confused...
 
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Old 07-10-06, 08:21 PM
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ya you got me confused here.????????????

answer his question above there is a miscommunication happening here. You point is not coming across clear.
 
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Old 07-11-06, 07:06 AM
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Originally Posted by davzack
I can't see how your car will run without any power getting to the fuel pump. Will it KEEP running? Or are you just starting it for a second with the relay out...in other words, using up the fuel in the lines. A car can't run without fuel...and no battery power to the fuel pump means no gas. I'm confused...

with the relay out it will run for awhile, then it dies and does start again
 
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Old 07-11-06, 06:19 PM
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Snuckers99 is correct: the fuel pump relay is backed up by the oil pressure switch which continues to operate the fuel pump as long as there is sufficient oil pressure. I would suggest you try replacing the oil pressure switch and fuel pump relay. This is the cheapest way to go without getting into a whole bunch of diagnostics.

A fuel pump relay is only about $9 and a new oil pressure switch is around the same amount for that vehicle. Try that and get back to us.
 
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Old 07-11-06, 11:21 PM
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Originally Posted by davzack
Snuckers99 is correct: the fuel pump relay is backed up by the oil pressure switch which continues to operate the fuel pump as long as there is sufficient oil pressure. I would suggest you try replacing the oil pressure switch and fuel pump relay. This is the cheapest way to go without getting into a whole bunch of diagnostics.

A fuel pump relay is only about $9 and a new oil pressure switch is around the same amount for that vehicle. Try that and get back to us.

when i went to go get the part i told the guy there what it was doing and he says it sounds like a Fuel Pressure Regulator
 
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Old 07-12-06, 03:24 AM
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sounds like it is getting to much fuel when you are attempting to start it dont see why it would make a difference in how it ran once the oil pressure built up enough to turn on the fuel pump but it would lean it out enough at start up that could mean the difference between the engine starting or not.
doubt it is a regulator problem if the regulator was leaking you should be able to see it as it is throttle body injection, suspect a sensor not reading correctly such as coolant temp or maybe an ecm problem have you had it to a shop and had the computer scanned to see if all the sensors are reading correctly.
 
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Old 07-12-06, 07:02 AM
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Originally Posted by bejay
sounds like it is getting to much fuel when you are attempting to start it dont see why it would make a difference in how it ran once the oil pressure built up enough to turn on the fuel pump but it would lean it out enough at start up that could mean the difference between the engine starting or not.
doubt it is a regulator problem if the regulator was leaking you should be able to see it as it is throttle body injection, suspect a sensor not reading correctly such as coolant temp or maybe an ecm problem have you had it to a shop and had the computer scanned to see if all the sensors are reading correctly.
ya i took it to a shop and they said all the sensors are reading what they are suppose. he said it sould like regulator is leaking so bad when the relay is pluged in that it is flooding the car, then when i pull the relay the car runs off the gas that has been flooded.
 
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Old 07-12-06, 09:09 PM
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you ever pull the vacuum hose off the regulator and see if fuel dribbles out
 
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Old 07-12-06, 10:03 PM
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if i knew were the hose was
 
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Old 07-13-06, 02:28 AM
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there is no hose the regulator is right beside the injector on this tbi car and it should be fairly obvious if it was leaking gas you would see it if you had the air cleaner off and looked for any fuel leaks around the regulator.
 
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Old 07-13-06, 07:29 AM
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no fuel is leaking but awhole alot is pour into the port
 
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Old 07-14-06, 02:34 AM
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from the injector I would assume have you chacked for injector pulse sometimes a computer can go bad and open the injector all the time when the key is on, a noid light should flash when cranking over if its lit up solid there is a prolem probably ecm related but could be wiring shorted to ground.
 
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Old 07-14-06, 08:22 AM
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I replaced the Fuel Pressure Reg and it works great now.

thanks for everyones help
 
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