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NO fuel pressure. Fuel Pump turns on still?

2000StreetRod

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fuel pump types

There are four types of fuel pumps: positive displacement roller cell; positive-displacement gerotor, positive-displacement roller vane; and the turbine. Most manufacturers have switched from the positive displacement pumps to the turbine since they are quiet, do not pulse, and have a longer service life. As I recall the turbine impeller has an electromagnetic clutch allowing it to slip as it comes up to speed (7,000 rpm).

Unfortunately, there are multiple possibilities for the pump running but there being low pressure: if a turbine pump the impeller could be excessively slipping; if a positive displacement pump the drive shaft could be slipping or broken; the pump motor speed or power could be low; the fuel pressure regulator could be defective. A weak pump motor could be due to worn brushes. Since the pump is sealed the brushes can't be replaced.

To isolate between a bad pump vs a bad fuel pressure regulator you could disconnect the pump outlet hose and connect the outlet to a pressure gauge. The pressure should increase to 65 psi within a few seconds after energizing the pump. Do not let the pressure increase above 80 psi.
 



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nlikens

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Ok quick update here:
I hooked the fuel pressure gauge directly up the pump and ran it and it was pumping fuel but the gauge didn't budge. Just to make sure there weren't any clogs in any of the fuel lines, I disconnected the fuel line from the fuel rail and ran compressed air through it. Also after removing the fuel line from the fuel rail I hooked the fuel pressure gauge up to the schrader valve and blew compressed air through the fuel rail and I got an exact reading on the gauge as I was blowing the compressed air through the rail which let me know the gauge was in fact working and there was nothing stuck in the fuel rail. Being that there was no pressure reading after hooking up the gauge directly to the pump, I'm going to have to concede that I will be buying a new fuel pump. Now I'm not sure if I should buy just the pump or the whole assembly so as to replace the FPR as well. Here is my set to test the fuel pressure on the pump
 






koda2000

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Ok quick update here:
I hooked the fuel pressure gauge directly up the pump and ran it and it was pumping fuel but the gauge didn't budge. Just to make sure there weren't any clogs in any of the fuel lines, I disconnected the fuel line from the fuel rail and ran compressed air through it. Also after removing the fuel line from the fuel rail I hooked the fuel pressure gauge up to the schrader valve and blew compressed air through the fuel rail and I got an exact reading on the gauge as I was blowing the compressed air through the rail which let me know the gauge was in fact working and there was nothing stuck in the fuel rail. Being that there was no pressure reading after hooking up the gauge directly to the pump, I'm going to have to concede that I will be buying a new fuel pump. Now I'm not sure if I should buy just the pump or the whole assembly so as to replace the FPR as well. Here is my set to test the fuel pressure on the pump

well the pump is around $60-$80 the whole assembly is quite a bit more. I guess you could buy just the pump and test it in water to see if it solves the problem. that way you could probably dry it and return it if you also need the FPR. just a thought.
 






2000StreetRod

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check valve & fuel gauge?

The intank fuel pressure regulator (FPR) is fairly reliable. I think the check valve in the fuel pump assembly fails more often than the FPR. When the check valve sticks open the fuel pressure bleeds off rapidly after the engine is shut off. That means that for the next start there is no residual pressure in the fuel rail and the starter has to crank longer for the pressure to build up enough for the engine to start. If you didn't have those symptoms before the fuel pump lost pressure I would suggest just purchasing a new, quality pump.

Also, if your fuel gauge is inaccurate or erratic then I suggest that you purchase the entire assembly.
 






RomeovilleIL

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You must replace the filter sock when you replace the pump! Airtech and Bosch are usually in stock for $60-115 at most autoparts stores, plus another $20-40 for the sock. Frankly that pricing is terrible, but that's simply because a fuel pump out is an immediate need item since the vehicle will not run without it. Mail order will save you at least half.

I have replaced a bunch of in-tank fuel pumps over the years and have yet to hear of a true difference in longevity or performance of one brand over another. Failures are almost always from not replacing the filter sock. I have used the $20 pump kits from Ebay and Amazon in five cars including two explorers with no issues whatsoever. Kits include sock, new orings, hose, and a wiring kit through Ebay or Amazon.

http://www.ebay.com/itm/New-Electri...es&hash=item4add649702&vxp=mtr#ht_6103wt_1124

Whatever route you choose, get the 2471 or equivalent model.
 






nlikens

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The pump was still under warranty so I took it to NAPA and got it replaced. Put the new pump in and it started right up. Thanks a million for all the input guys
 












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