1999 Trans Am low fuel pressure
04-26-2016, 05:49 PM
#1
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1999 Trans Am low fuel pressure Hello all,
I am new to LS1tech and the proud new owner of a 1999 T/A, WS6 with only 13k miles. Unfortunately, my joy was short lived when the car became hard to start, and ran horrible once it did. I suspected low fuel pressure, so I checked the F/P fuse, F/P relay (swapped it with another), changed the fuel filter which was clean, and then finally got a hold of a fuel pressure test gauge. At the fuel rail, I have 0 psi when the key is turned on. As the engine cranks, the fuel pressure slowly rises to about 20 psi before the engine will fire. Once running, it will barely go past the 20 psi mark. From what I understand it should be in the 55-60 psi range, and should have it when the key is turned on. Before I go the joyous route of yanking the fuel tank and replacing the pump and regulator, is there anything else that needs to be checked?
Thanks in advance for all the help! I hope I've posted this in the right place!!!
I am new to LS1tech and the proud new owner of a 1999 T/A, WS6 with only 13k miles. Unfortunately, my joy was short lived when the car became hard to start, and ran horrible once it did. I suspected low fuel pressure, so I checked the F/P fuse, F/P relay (swapped it with another), changed the fuel filter which was clean, and then finally got a hold of a fuel pressure test gauge. At the fuel rail, I have 0 psi when the key is turned on. As the engine cranks, the fuel pressure slowly rises to about 20 psi before the engine will fire. Once running, it will barely go past the 20 psi mark. From what I understand it should be in the 55-60 psi range, and should have it when the key is turned on. Before I go the joyous route of yanking the fuel tank and replacing the pump and regulator, is there anything else that needs to be checked?
Thanks in advance for all the help! I hope I've posted this in the right place!!!
04-26-2016, 08:44 PM
#2
Just replaced the fuel pump in my 2001 Trans Am with 18,000 miles because of a similar condition. I suggest keeping the tank full at all times to keep the pump submerged while in storage. I let mine sit with 1/4 tank for a winter and it seized up.
04-26-2016, 09:18 PM
#4
Yes, I wasn’t willing to cut the floor pan to create an access panel. I have a lift and that made the decision easier, but it was still a lot of work. I recommend planning on spending an entire day on the project.
Assuming the car is clean underneath, you won’t have much grime to remove, but soaking all bolts with Kroil or similar is a good idea. Power-washing may be good if its grimy. It doesn’t require much more than a good assortment of basic hand tools.
Basically, you have to let the axle hang down on the control arms. That involves removing the panhard bar and torque arm, lower shock mounts, brake cables, etc. Pay careful attention to the position of the coil springs and the upper insulators as they’ll likely fall out when you remove the springs. The springs and insulators need to be reinstalled as they were.
The exhaust comes down next, then the heat shields. You then unclip the fuel lines from the tank and bulkhead wiring, etc. Before unbolting the straps that hold the tank to the body, you need to remove the access panel in the driver’s side wheel well and unbolt the filler neck support from the body. Then remove the cap and trim panel in the gas cap door. The tank is then ready to come down.
Depending upon how much fuel is in the tank, it’s good to have a helper guide it out, taking extra caution to not break the plastic filler neck on the way out.
Installing the new pump is straightforward. I decided upon a new GM pump, and it’s an updated design that fits just as it should but requires removing the original weather-pack connector from the main harness and installing a new one, which is supplied. The pickup sock is also internal—the original pump has an external sock. Be prepared for the price on the pump! GM asks $770! Jobber is $550.
Reinstallation involves reversing the process.
Assuming the car is clean underneath, you won’t have much grime to remove, but soaking all bolts with Kroil or similar is a good idea. Power-washing may be good if its grimy. It doesn’t require much more than a good assortment of basic hand tools.
Basically, you have to let the axle hang down on the control arms. That involves removing the panhard bar and torque arm, lower shock mounts, brake cables, etc. Pay careful attention to the position of the coil springs and the upper insulators as they’ll likely fall out when you remove the springs. The springs and insulators need to be reinstalled as they were.
The exhaust comes down next, then the heat shields. You then unclip the fuel lines from the tank and bulkhead wiring, etc. Before unbolting the straps that hold the tank to the body, you need to remove the access panel in the driver’s side wheel well and unbolt the filler neck support from the body. Then remove the cap and trim panel in the gas cap door. The tank is then ready to come down.
Depending upon how much fuel is in the tank, it’s good to have a helper guide it out, taking extra caution to not break the plastic filler neck on the way out.
Installing the new pump is straightforward. I decided upon a new GM pump, and it’s an updated design that fits just as it should but requires removing the original weather-pack connector from the main harness and installing a new one, which is supplied. The pickup sock is also internal—the original pump has an external sock. Be prepared for the price on the pump! GM asks $770! Jobber is $550.
Reinstallation involves reversing the process.
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