97 s10 Truck will not start or run?

Well my truck will not start or run when hot or cold it will crank over. I can pour a little gas down the T/B and it will start annd run . I have to do this every time i want to go anywhere. I was tlod that it was the F/pump, the F/pressure reg. or the egr valve. Can somone give me some info on what it could be.



P.S. i have checked the fuel pressure (not running key on 58psi, running 52psi) changed the F/filter also. No engine lights on to let me know anything but they do work.

58psi is too low, read on...

Fuel pressure is not monitored by the On Board Diagnostic (OBD) system and therefore cannot set a Diagnostic Trouble Code (DTC), or illuminate the Service Engine Soon (SES) light.

Fuel pump operation:
The fuel pump circuits are designed to energize the fuel pump through a relay continuously any time the key is in the START position. When the key is in the RUN position the fuel pump will operate provided the engine is running. If the engine stalls, or is not running for any reason, the PCM/VCM will shut off the fuel pump after approximately 2 to 3 seconds.

Fuel pressure test:
Install the fuel pressure gauge to the test port near the distributor. Turn the key to the RUN position but do not start the engine. While the fuel pump is running, fuel pressure must be 60-66psi. After approximately 2 to 3 seconds, the fuel pump will shut off. Fuel pressure must remain between 55-60psi for several minutes. A drop in pressure below 55psi indicates excessive leak down. Possible places to leak are the fuel pressure regulator, the fuel lines under the upper intake manifold, a fuel injector that is stuck open, a leaking fuel line or connector, or the check valve in the fuel pump assembly.

Here is a link to an inexpensive, and adequate fuel pressure tester: http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92699 Accurate diagnosis of an internal fuel leak requires additional test equipment. In some cases it requires the removal of the upper intake manifold.

Post your results and we can continue diagnosing.

So could you please tell me why the engine runs when i pour gas down the throttle body??

P.S. I already have a pressure tester that is how I know the pressure of the pump but thankes anyway on the link... you have been the only one to give me that info. This has been going on for 9-10 months now

The fuel pressure regulator, (under the upper intake manifold) restricts the fuel flow which allows the fuel pump to build pressure. Regulators are factory set anywhere from 60 to 66 psi. When that pressure is achieved, it bleeds off the excess fuel & pressure back to the tank and maintains a constant pressure at the injectors. The injectors will not open below approximately 57psi, sometimes as low as 55psi. The fuel that you pour in is enough to get the engine started and run half way decent. If the fuel pump can not build at least 60psi, you'll have driveability issues. Your 58psi is below that threshold. Does the pressure hold after the pump shuts off?

The fuel pressure regulator, (under the upper intake manifold) restricts the fuel flow which allows the fuel pump to build pressure. Regulators are factory set anywhere from 60 to 66 psi. When that pressure is achieved, it bleeds off the excess fuel & pressure back to the tank and maintains a constant pressure at the injectors. The injectors will not open below approximately 57psi, sometimes as low as 55psi. The fuel that you pour in is enough to get the engine started and run half way decent. If the fuel pump can not build at least 60psi, you'll have driveability issues. Your 58psi is below that threshold. Does the pressure hold after the pump shuts off?


Yes It does. But it still won't start after it runs for a while. I will do another pressure test to make sure my numbers r correct.

That's not surprising with only 58psi.

Fuel pressure holding indicates there are no leaks. That test covers everything from the check valve in the pump, the lines to the intake, the injectors, and the regulator. The factory only provides one place to check fuel pressure which makes checking fuel pump maximum output tricky. Without other test equipment, the only way to accomplish this is to slowly restrict the fuel return line while watching the fuel pressure. DO NOT allow fuel pressure to rise above 75psi or the regulator can be permanantly damaged. For the duration of this test, the fuel pump must be running, and the engine off. A fused jumper wire works well to energize the pump.

That's not surprising with only 58psi.

Fuel pressure holding indicates there are no leaks. That test covers everything from the check valve in the pump, the lines to the intake, the injectors, and the regulator. The factory only provides one place to check fuel pressure which makes checking fuel pump maximum output tricky. Without other test equipment, the only way to accomplish this is to slowly restrict the fuel return line while watching the fuel pressure. DO NOT allow fuel pressure to rise above 75psi or the regulator can be permanantly damaged. For duration of this test, the fuel pump must be running, and the engine off. A fused jumper wire works well to energize the pump.


Cool will do that. Is there anything else that I have to check? I figure I may as well cover every thing when I get to checking this. Would like to be though and give the right info to everyone so I can fix this. Thanks

To check max output without having to worry about regulator damage, disconnect the fuel line where it goes into the fuel filter and connect the gauge to the line. It will take some "plumbing creativity" to make the connection from the line to the gauge. BRIEFLY energize the pump and check pressure. The pump should build a MINIMUM of 75psi, if not, it's time for a new pump.