Problem with Chevrolet 4.3 Vortec fuel pressure / oil pressure relay
I need some information regarding a situation with a 4.3 Vortec engine in
a Chevy Pick-Up. The engine started hard, which was an indication that
the fuel pressure relay was faulty or weak, and as a result, would not
achieve a speed of over 50 MPH on the road. This seems peculiar due to
the fact that the oil pressure relay is supposed to act as a backup for
the Electronic Fuel Ignition system in this particular set-up. Once the
oil pressure achieves a safe level, the oil pressure relay has the ability
to take precedence over the EFI. The fuel pressure relay has since been
changed; the problem that I have is that I have been told that a faulty
fuel pressure relay can render and EFI system useless. I find this hard
to believe due to the fact that the oil pressure relay is able to function
as a back-up in this situation. Any suggestions?
were is the oil preesure switch located?
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Re: Problem with Chevrolet 4.3 Vortec fuel pressure / oil...
A bad fuel pump relay will not cause vehicle to only run under 50. the oil pressure switch does bypass relay when pressure builds up. if you are having problems with running need to check fuel pressure. possibly caused by clogged fuel filter
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You'll have to figure out if it is a fuel or ignition problem to proceed. Is the check engine light on ? Have you checked for trouble codes ? It could be a relay, the ignition module, coil, fuel pump blockage, or a list of other things. Is the oil pressure light on ? If this is a vortec engine, it requires 60psi or more of fuel pressure to run. Have you checked the fuel pressure and is it enough ?
Sounds like the fuel pressure regulator is stuck in the open position.I am trying to remember if this engine(Vortec?)has a return line to the tank.If it does,try disconnecting the return(smaller) line,and use something to plug the fitting on the outlet of the fuel on the intake(Use a piece of fuel hose and a bolt_make sure you use a hose clamp,as there is 50 PSI of pressure)
If this truck has the 4.3L vortec motor it will not start with 40-45 PSI fuel Pressure.Thius engine requires approx. 56 PSI fuel pressure or it will not start. The fuel pump more than likely needs to be replaced this is a common problem with the 4.3L vortec engine.Change the fuel pump and your problems will be solved.
gmc put two sistems to the fuel pump 1 fuel pump relay 2 oil pressure sensor if the relay is bad it takes longer to start until oil pressure is buildup if the oil is too old or too tick or the oil pump is old not building enogh pressure all that together is very bad but depend how many miles on
without starting the engine position the key to the on position. you can hear the fuel pump operationing for 4 to 6 seconds upon having the key on. if not heard running check the fuel pump fuse, the fuel pump relay, and the engines oil pressure switch. they all work the pump you see the engine oil pressure switch runs the pump untill the engine reaches normal pressure once the pressure is reached to the normal range the computer shuts that circuit off and turns the fuel pump relay on
You need a new fuel pump relay. The engine fires up and runs off the oil pressure switch untill the oil pressure PSI is reached at normal operating conditions. When the oil pressure reaches its operating PSI the PCM or engines computer will shut off that circuit and turns on the fuel pump relay to run the fuel pump untill you shut the engine off
The oil pressure sending unit should be located behind the distributor way in the back angled away from the engine, fuel filter been changed? www.aceautomotive1.com if you findd this information helpful please give me a good rating
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in the fuel tank , MIninum fuel pressure for the vehicle if it has a vortec engine is 60 PSI the vehicle will not run on less than 60PSI
If you have a non vortec engine the fuel pressure is around 9 PSI
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