95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?
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HT4100 4.1, 4.5, 4.9 Discussion, 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump? in Cadillac Engine Technical Discussion; Hey guys, I am back again after a few months of being MIA. With a new problem. I have had ...
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    brandond25 is offline Cadillac Owners Fanatic
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    95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Hey guys, I am back again after a few months of being MIA. With a new problem. I have had problems with my car starting and running smoothly for a while. Some said EGR, some said check FPR. Here is the deal with the FPR. I can unplug the hose from the nipple with it running, without it running, with the key on (not running) and it still runs. No fuel coming from the FPR. But no difference in idle either. I checked the Fuel pressure with my dads gauge via the valve on the fuel rail. It is only getting somewhere between 18-22p.s.i at times. Could it be the fuel pump, or another issue with the FPR, or an issue with something totally from the two?

    When I start it, and hit the gas to goose it, it bogs down. Replaced fuel filter, no change. I have to feather the gas pedal until it smooths out, still not completely smooth either. Then put it in gear and go to drive and it misses like a son of a gun. Backfires under the hood. Then all the sudden up up and away it has power. Does this the whole time i am driving, hesitation on acceleration. The spark plugs, wires, distributor and rotor caps are new. So could it be the FPR or fuel pump? Book I have says it should have 40-50p.s.i fuel pressure. When we were removing the fuel filter we had to get out from under the car because of all the pressure being relieved. We didnt relieve the pressure prior to removing the filter. And the gas was spewing from all around the filter like it had a ton of pressure. But with the gauge, showed 22 was the highest. Please help. I am hoping this is why my car has been knocking too. My dad says lower end knock. My brother said when he was there it was fuel. 22p.s.i sure explains a lot though and the stinky exhaust, of lean mixture. Please help if you can. Thank you much!

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    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Your fuel pump is shot. 22 psi is WAY to low.

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    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    The low pressure from the weak pump is causing the engine to run lean which is what causes the knock. I'd change it before it leaves you stranded somewhere.

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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Please be careful with fuel spillage. One tiny spark and you're on fire.

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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    I usually have a big fan blowing away from me when I work on fuel systems. It keeps vapors from accumulating in one area and if there is a fire, the fan will blow the flames away from me. A fire extinguisher is a must, no drop lights, smoking etc... common sense.

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    brandond25 is offline Cadillac Owners Fanatic
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    You know, this is going to sound weird. But my car has been running like that a long long time. I thought it was spark plugs, this and that, never thought fuel pump. I always thought either it works or it doesnt. So, thank you all for the information. I am happy I at least know what the hek was causing it. All this time I thought I had bearing knocks, etc it must have only been the fuel pump. But to all who own the 95 with the 4.9 the fuel pump will go out slowly, and I do mean slowly. You are right though. Before I got it home last trip out I liked to have never gotten it started. Now it will start, run half decent if that idling and then putt out when you try to drive it.

    Now, my next question, can the fuel pump be seperated from the sending unit and replaced? Can I buy just the pump or do I have to buy the entire assy?

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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Try Rockauto.com, Advance auto, Napa, etc. Most places require you to purchase the filter sock with the pump to get the warranty. IMO, if you're going to drop the tank you might as well replace what you can WHILE you can. I dont think GM put in pump access panels in the trunk until 97 or so...

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    HUF
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Are you sure the fuel pressure gauge you used is good?

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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    if it stalls when you go around sharp corners when you have less then a half a tank of gas you might want to replace the tank as well .

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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    I always thought either it works or it doesnt.
    Sometimes that is the case.
    But to all who own the 95 with the 4.9 the fuel pump will go out slowly, and I do mean slowly.
    And sometimes that is the case.

    The point is, they can die an instant death or linger for months. No hard and fast rule on fuel pumps.

    Yes, I think you can replace the pump only and do not have to replace the sending unit.

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    steelybill is offline Cadillac Owners Enthusiast
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    The last in-tank pump I replaced had been seeping fuel into the pump motor, which gummed up the brushes etc and slowed the pump down. Maybe that's the scenario on your pump.

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    creeker is offline Cadillac Owners Connoisseur
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Quote Originally Posted by Sevillian273 View Post
    Try Rockauto.com, Advance auto, Napa, etc. Most places require you to purchase the filter sock with the pump to get the warranty. IMO, if you're going to drop the tank you might as well replace what you can WHILE you can. I dont think GM put in pump access panels in the trunk until 97 or so...
    I missed out on the trunk access by one year with my 97 sts, it started in 98.

  14. #13
    brandond25 is offline Cadillac Owners Fanatic
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Quote Originally Posted by HUF View Post
    Are you sure the fuel pressure gauge you used is good?
    Yup. My dad tested it on my stepmoms car to be sure of that. Hers also pushes 40psi. Mine was 18-22 depending on how long it set between testing.

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    brandond25 is offline Cadillac Owners Fanatic
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Quote Originally Posted by Ranger View Post
    Sometimes that is the case.

    And sometimes that is the case.

    The point is, they can die an instant death or linger for months. No hard and fast rule on fuel pumps.

    Yes, I think you can replace the pump only and do not have to replace the sending unit.
    Well I had to break down and buy the pump, the whole assembly. No parts stores here sell just the pump. It did come with everything though. No sending unit though. There isnt one for this year apparently. The gauge and sock were all included. Actually they didnt even sell the sock by itself, the strainer sock. So here, in my side of the world if the strainer is bad, its whole new assembly time. I found a couple on ebay but the people selling wouldnt answer back on whether or not it could be replaced without replacing the whole assembly. It was only $250 though with tax and all at autozone. Not too too bad.

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    brandond25 is offline Cadillac Owners Fanatic
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    Re: 95 Deville base 4.9 fuel pressure issues, FPR or fuel pump?

    Quote Originally Posted by quins90lac View Post
    if it stalls when you go around sharp corners when you have less then a half a tank of gas you might want to replace the tank as well .
    Huh? How would the tank do that? If you had to replace the tank did it have something to do with you bottoming it out a lot or something? I have replaced my tank once. But only because the shocks were bad and the pump kept going out. But I spent $100 and got that fixed. Might not ride Cadillac smooth anymore but its up high enough I would have to go some place pretty stupid for me to go for the tank to get damaged again.

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