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Won't Stay Running


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sboom
Novice

Mar 2, 2010, 8:12 AM

Post #1 of 10 (4251 views)
Won't Stay Running Sign In

I have a 1998 Pontiac Grand Prix GTP, 3.8, super charged,175k, I was driving the car when it just quit running. I can restart but it will only run for about 20 seconds and kill. If you feather the pedal I can keep it running but very rough and it will die as soon as it is put into gear.


nickwarner
Veteran / Moderator
nickwarner profile image

Mar 2, 2010, 8:53 PM

Post #2 of 10 (4243 views)
Re: Won't Stay Running Sign In

check your fuel pressure. Also, is the engine light on? If so what are the codes?


Sidom
Veteran / Moderator
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Mar 2, 2010, 10:39 PM

Post #3 of 10 (4242 views)
Re: Won't Stay Running Sign In

Follow Nick's advise 1st and get the codes read.

Once you have the codes pulled a quick check you can try would be to disconnect the MAF sensor and see if this makes a difference in the way it runs. If it runs better or can be driven you may be looking at a bad sensor but this will set a code so you do want to have them pulled 1st before you start setting them...........


sboom
Novice

Mar 5, 2010, 10:55 AM

Post #4 of 10 (4229 views)
post icon Re: Won't Stay Running Sign In

I did have the codes read and they all came back as evap codes high pressure,low pressure, evap malfunction. M ore than likely they came up when I was forcing the car to stay running.
the fuel pressure is in range. when the car starts and runs for a short time the fuel pump does not stay operating after the car is started. I turn the key on the pump pressures up but does not continue once I start the car.
Fuel Regulator??


bioguy
User

Mar 6, 2010, 2:39 PM

Post #5 of 10 (4221 views)
Re: Won't Stay Running Sign In

Could be fuel reg and a few other things. It could have a faulty oil sender if it is a three wired unit. They need to have good oil pressure to allow the fuel pump relay to continue to run ( safty feature on some cars) Turn key on and pump pumps up to pressure then start, then the oil sender has to read around 4 pounds of pressure to keep the relay open to pump. Had this on a car once with a bad loose wire. You may not have that but it is worth a check. Also check for good gas cap, faulty relay.
Just a couple thoughts from here.


nickwarner
Veteran / Moderator
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Mar 7, 2010, 2:24 PM

Post #6 of 10 (4212 views)
Re: Won't Stay Running Sign In

pull the vacuum line off the pressure regulator and see if there is fuel leaking past the diaphragm. If so, replace your regulator


Hammer Time
Ultimate Carjunky / Moderator
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Mar 7, 2010, 3:37 PM

Post #7 of 10 (4208 views)
Re: Won't Stay Running Sign In


Quote
It could have a faulty oil sender if it is a three wired unit. They need to have good oil pressure to allow the fuel pump relay to continue to run ( safty feature on some cars) Turn key on and pump pumps up to pressure then start, then the oil sender has to read around 4 pounds of pressure to keep the relay open to pump.


I'm afraid that's not true. When they are wired through the oil pressure switch, it is a redundant power supply to the fuel pump. The car will run without either the oil pressure switch or the relay but not both of them but in this particular situation, the oil pressure switch isn't even in the circuit for the fuel pump.

This circuit has a prime wire at the relay that you can power to see if the pump holds pressure to determine if the pump itself is good or not. That will determine where to go next. This is a 2 speed pump on this car and it has a resister and second relay in the circuit.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



sboom
Novice

Mar 8, 2010, 11:01 AM

Post #8 of 10 (4187 views)
post icon Re: Won't Stay Running Sign In

Where would the prime wire be located. I'm aware of the dual speed and dual relays, I switched them to see if it had an impact on the way the car ran but there was no differcnce. The pump pressures up to about 53# and drops to about 43#.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 8, 2010, 11:08 AM

Post #9 of 10 (4185 views)
Re: Won't Stay Running Sign In

There is a terminal off the fuel pump speed control relay where you can apply power right to the pump.






~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



sboom
Novice

Mar 8, 2010, 12:21 PM

Post #10 of 10 (4179 views)
Re: Won't Stay Running Sign In

The car will start and run for 10 to 20 seconds. When pressure was checked it goes up to 53# then falls to 43#. After the key is turned on the pump energizes but cuts out as soon as the car starts and it kicks back in once the car stalls.






 
 
 






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