Pontiac G8 Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
2008 Pontiac G8GT. the car quit starting. We checked the relay and fuse for the fuel pump and they were fine. replaced the fuel pump and that didn't help. Kind of seems like the pump isn't getting any power. Battery, starter and alternator are fine. Any ideas please? and Thank you
 

·
Premium Member
Joined
·
4,670 Posts
Is it cranking, but not starting or not cranking at all? Do you hear the fuel pump run a few seconds when the ignition is switched on prior to starting the vehicle?
 

·
Premium Member
Joined
·
4,670 Posts
Very well. Are you able to verify whether or the fuel pump is getting a signal to the sending unit or not? Am presuming the answer is no. Is checking the fuel pump fuse and relay merely just a visual inspection? Was the fuel pump fuse checked for current as well? The fuse can look good, but if there is no current being sent to it then the item won't work. Experienced a similar situation last weekend, and at first glance, most people would have simply replaced the fuel pump since it didn't run when the ignition was turned on. However, upon checking for current to the fuel pump discovered it had none which either meant a blown fuse or something other than a faulty fuel pump. Did a little more digging and the culprit turned out to be a blown fuse for the injectors(a) 20 amp that shut off current to the fuel pump fuse. This may not represent your particular problem, but gives an idea on the scope of troubleshooting.
 

·
Premium Member
Joined
·
4,202 Posts
Tough to image changing the pump right off the bat (that is one difficult an time consuming job on a hunch) If you have a little help, you could at least verify or eliminate the pump. Have a friend get there ears as close to the tank as possible on the passenger side (from underneath). Turn the ignition to the full on position. The pump will be commanded to run for about 3 seconds an then shutdown. Pretty much impossible to hear that pump from the drivers position.
 

·
Premium Member
Joined
·
4,202 Posts
^^^^Different vehicle, but one of my boys owned a 97 Chevy truck at one time. I helped him change a failed fuel pump, only to have it crap out a while later. Turns out an internal connector that fed power to the pump, had (hard to see unless looking for it) burned wiring/pins at that connector. It would cause the pump to slowly die. Changed the pump again *after* repairing the connector and problem solved. *Maybe* you have something similar causing the problem in your car.
 

·
Registered
Joined
·
31 Posts
^^^^Different vehicle, but one of my boys owned a 97 Chevy truck at one time. I helped him change a failed fuel pump, only to have it crap out a while later. Turns out an internal connector that fed power to the pump, had (hard to see unless looking for it) burned wiring/pins at that connector. It would cause the pump to slowly die. Changed the pump again *after* repairing
the connector and problem solved. *Maybe* you have something similar causing the problem in your car.
This is not the first time i hear this suggestion... now I'm wondering... I already replaced fuses, relays, went through a different tune and many pumps... any idea where to start checking these wires?
 

·
Premium Member
Joined
·
4,202 Posts
If you have R&R'd several pumps already, I sure hope your car has the improvised access cover/plate setup under that rear seat pan. If not, I'm impressed you haven't blown a gasket by now (dropping that tank over an over). Pump power arrives at the back thru a 14 pin connector (labeled A thru P) that is along the right side rail (outboard of the fuel tank). Verify that pin A (power) an pin H (ground return) on both haves of that connector are in good condition. These are the pump wires. If OK, due the same thing at the 10 pin connector attached to the pump/fuel level sensor housing going into the tank. Check pin 5 (pump power) an pin 4 (pump ground return). If OK, it appears that there is a replaceable harness section within the pump/fuel level sender housing. The bad is that (that) wire harness P/N 92193774 is no longer available. If it looks like it has a problem at either end of that wire section, its either find a way to repair *it* or you might have to buy the whole housing assembly that comes with everything new. It has a P/N 92203242 but comes with a steep price of about $397
 

·
Registered
Joined
·
31 Posts
If you have R&R'd several pumps already, I sure hope your car has the improvised access cover/plate setup under that rear seat pan. If not, I'm impressed you haven't blown a gasket by now (dropping that tank over an over). Pump power arrives at the back thru a 14 pin connector (labeled A thru P) that is along the right side rail (outboard of the fuel tank). Verify that pin A (power) an pin H (ground return) on both haves of that connector are in good condition. These are the pump wires. If OK, due the same thing at the 10 pin connector attached to the pump/fuel level sensor housing going into the tank. Check pin 5 (pump power) an pin 4 (pump ground return). If OK, it appears that there is a replaceable harness section within the pump/fuel level sender housing. The bad is that (that) wire harness P/N 92193774 is no longer available. If it looks like it has a problem at either end of that wire section, its either find a way to repair *it* or you might have to buy the whole housing assembly that comes with everything new. It has a P/N 92203242 but comes with a steep price of about $397
Yes sir, G8Only fuel pump access cover is installed! Got it just in case I needed to do this again, and sure enough. It paid off. Besides, i have plans for the car so i felt like this was a good purchase. . . And thank you for your help by the way... question... would a tune affect the fuel pump voltage? Would this cause the pump to die slowly? Now that i recall, since the car was tuned for DoD delete, this issue has been going on.
 

·
Premium Member
Joined
·
4,202 Posts
Being stock only, I can only give you a guess on that. From random posts over the years, my take is that the OEM pump can produce enough volume an maintain the pressure required for the small changes you have done so far. If others read this, they may be able to confirm this info, or let you know if a higher output GM pump or a pump from a performance company is needed.
 

·
Registered
Joined
·
31 Posts
Being stock only, I can only give you a guess on that. From random posts over the years, my take is that the OEM pump can produce enough volume an maintain the pressure required for the small changes you have done so far. If others read this, they may be able to confirm this info, or let you know if a higher output GM pump or a pump from a performance company is needed.
Cool well thanks for the help, one more thing to check. And yea, hopefully someone else can give me some more ideas. The car has 137xxx miles, DOD delete and stock ls3 cam. Some exhaust work and tune.
 

·
Registered
Joined
·
1,848 Posts
First thing I'd do when it's not starting is check for fuel pressure as there's a chance that it might be something not fuel related (e.g., ignition). Also, if there's a tune, it may be set to disable speed density. If there's an issue with the mass airflow sensor wiring or connector in that case, it won't start and may not reach a point where it can trigger a code.
 
1 - 13 of 13 Posts
Top