Question about 2001 Chevrolet Blazer

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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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  • slickdashock Mar 17, 2009

    im encountering a simuliar problem'have 60 pounds pressure, new pump, filter,converter not pluged,full tune up,good timing,have inj pulse any ideas?

  • gasitjr May 11, 2010

    There is a (fuel PUMP relay) and a (fuel pressure regulator).The relay turns pump on and off. The regulator controls fuel pressure according to engine vacuum. The oil pressure sending unit (switch) will disable the fuel pump relay if pressure falls below a preset minimum.What year is it? Is service engine soon light on?Has it been scanned for trouble codes or data ? Possabilities include; weak fuel pump, dirty injector(s), engine timing, plugged catylitic convertor, dirty or failed mass air flow sensor, ect.... Need more info...

  • Anonymous Mar 23, 2014

    oil gauge not working. no signal to cluster. runs with out fuel relay not hooked up

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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

Posted on Feb 14, 2009

  • MartysCycle Dec 17, 2010

    97 GMC 4.3L - I have deduced that the relay briefly operates the fuel pump to pressurize the system when you turn the ignition on. Once the engine is started the fuel pump will continue to run even if this relay is completely removed. If you get stuck from an inoperative relay you can manually jump pins 30 and 87 for a couple seconds to prime (my relay pins were labelled on the bottom as 30,85,86,87,87a with 85/86 being the actuating circuit).

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1 Answer

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