This truck has an OBDII computer on board. When i turn the key to the
run position the fuel pump used to come on a build pressure in the
line for a few seconds. It has stopped doing this. When i turn the
key to the start position it turns over and grinds and grinds, no
fuel. I have replaced the fuel pump, oil pressure/fuel pressure
switch, and checked the fuel pump relay. I have also scanned the
onboard computer and it has no trouble codes. Any help would be
appreciated. Thanks in advance for anyones help.
98 gmc 5.7 fuel gauge crazy works wen in gear, trouble starting ocasionaly have to pour fuel in t.b., drive on highway @ speed and once back at idle will die, can feel power loss and regain in 2-3 min incrimints on highway ???
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Re: 1996 GMC K1500 Pickup Starting Problem
I would try a fuel filter first. the fuel gauge going crazy is most likely the sender they go bad and eventually stop working. the bummer is you have to replace the fuel module. these aftermarket are about 200 bucks. the module comes with the pump and sender which is the next part you want to look at. gm has some issues with the harness to the fuel pump externaly. it actualy will melt and start to lose conection. i would check this by visualy inspecting the plug on top of the tank. unplug it and take a look. if it is at all disscolored replace the pump (module). the new pump comes with a replacement harness (make sure its in the box)hope this helps and good luck
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You should have the fuel system tested , fuel pump pressure an flow test . an static fuel pressure . There is a check valve in the fuel line inside the fuel pump module , this could be bad . You could try just turning the key to run, not start 4 or 5 times to see if this adverts this problem . This will build fuel pressure up , you see when you turn the key on the PCM/ECM -engine computer energizes the fuel pump for two seconds building fuel pressure .
You may have a bad check valve in the fuel pump module. Try turning the key to the on position three or four times ,to build up fuel pressure in fuel lines . When you turn the key to the on position the PCM energizes the fuel pump relay for two seconds . The check valve is there to keep fuel pressure in the fuel lines, if bad it can cause a hard start first start of the day. You could test it with fuel pressure gauge .
Most likely fuel pressure regulator or injectors under intake plenum leaking fuel. Remove intake plenum look for washed down intake. It will visibly be clean & no carbon build-up. Energize fuel rail. With plenum off, reattach fuel line. Turn key to run. Watch for fuel leaking in back (fuel pressure regulator) or out nylon lines (fuel injectors). Very common problem.
turn the ignition to the on position without starting the engine. you should hear the fuel pump running for 5 seconds inside the fuel tank. if not heard replace the engines oil switch. that starts the pumps circuit when the key is turned on. after the engine builds up its normal oil pressure the computer shuts that oil switches circuit off and turns on the fuel pump relay
When you turn the key to the "run" position, listen and see if you can hear a buzzing noise coming from the under the bed. This is your fuel pump buzzing for 2-3 seconds. If it isnt buzzing, you most likely have a faulty fuel pump. If it does buzz, check the fuel pressure. There is a schrader valve on the fuel line under the hood near the back of the intake manifold. You will need a fuel pressure gauge to check the pressure. If it doesnt build 50-60 psi, it will most likely, again, need a fuel pump.
u can try replacing the relay. when u turn the key to the position right before starting position which is the position it would be in when u start a car and let off key because car started, well this is somting to try turn the key to position right before starting position have sombody listing down by fuel tank and see if tey can hear pump come on, try a couple of times to make sure they can hear, also the pump will only come on for about 2 seconds each time u put the key in that position, if u do hear the pump come on each time u do that that means pump is working if so u need to build up fuel pressure which could b anywhere from 20 to 60 pressure, to build up pressure u need to turn the key to same position turn key off turn key back to that position then off and do it like 50 times each time u do that the pump is on for only 2 seconds only building a half to one pound of pressure thats why u haft to turn key somany times to build it back up, if u try that and car keeps almost starting but doesent then u need to build up a little more pressure. NOTE make sure u have gas, also most electric fuel pumps will go out when turned on dry
Sounds to me like either your pressure regulator is bad or you have a loose fitting somewhere in the fuel line from the fuel pump to the engine. When you turn your key to the on position, you should hear the whine of the fuel pump until it builds pressure. When you shut the truck off the pressure regulator should retain the pressure for a certain amount of time but if it don't close then air is allowed into the fuel line and the fuel drains down to fuel line away from the engine. Next time you try and start the truck after it has sat for a while try turning the key on until you hear the fuel pump whine shut off, then repeat it 3-5 times and then try to start it. Basically that is running the pump enough to get the fuel back up to the injectors. Check for loose fittings in the fuel line, or cracks in the fuel line and if all that is fine then replace the regulator.