Fuel Pump Dilemma! Help if you can?

[Diff Whack Daddy]

If that is the case, and the voltage is steady, than whichever item controls the fuel pressure needs to be replaced. Is the regulator a seperate replaceable item or do you have to replace the entire in tank sending unit? And finally, the fue line on the damper gores some where. If it goes back to the tank, then it is a fuel return line. If the pressure regulator is in the tank, what is the purpose of the diaphram on the fuel rail? Possibly a pressure relief valve in case the in tank regulator fails. If thatls the case, whatls the point of the vacuum line on it?

Rick, do you have a picture of your in tank sending unit? If not, can you describe it to include the number of tubes, if there is two, does the second have a rubber nozzle on it, and do you see anything in the output line that could be the regulator.

Just out of curiousity, since the OHV was only in about 33% of the 99 and 2000 X's, could the returnless system be used for the SOHC engines?
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[n0xdw]

If that is the case, and the voltage is steady, than whichever item controls the fuel pressure needs to be replaced. Is the regulator a seperate replaceable item or do you have to replace the entire in tank sending unit? And finally, the fue line on the damper gores some where.

The line from the damper goes to a vac port on the intake. In all cases unlike a pressure regulator if it goes bad it will put fuel into the intake. If it does not leak it is good. It has no effect on the pressure other then to try to damp pulsations. In other words it will try absorb the pulsations caused by the injectors turning on and off.

If it goes back to the tank, then it is a fuel return line. If the pressure regulator is in the tank, what is the purpose of the diaphram on the fuel rail? Possibly a pressure relief valve in case the in tank regulator fails. If thatls the case, whatls the point of the vacuum line on it?

Rick, do you have a picture of your in tank sending unit? If not, can you describe it to include the number of tubes, if there is two, does the second have a rubber nozzle on it, and do you see anything in the output line that could be the regulator.

Just out of curiousity, since the OHV was only in about 33% of the 99 and 2000 X's, could the returnless system be used for the SOHC engines?
Posted via Mobile Device

The system used for the SOHC was similar but different. It also was a returnless system, but it relied on pulse width modulation of the fuel pump power to control pressure.
It probably would not hurt to replace your relay though. Have you inspected the entire system from the tank to the engine to ensure the line has not been damaged or squished in any way?

 

[Diff Whack Daddy]

So after a lttle more research, it looks like up until manufacture date of Feb of 200, you could have either of both systems. The returnless, or the return type. If it's a US or Canada version and the VIN begins with 1,4,5, or 2 then you would use this which only has the one output and what looks to be a fuel pressure device on it.

If your vin ssttarts with 3 and your tank sending unit looks like this having two tubes, then your system has a return line and the fuel pressure "damper" on the fuel rail controls the pressure.

If the spring that provides pressure for the diaphram breaks, and the integrity of the diaphram is still intact, then the part can fail without leaking fuel into the vacuum line. Rare, yes it is, but it does happen, usually from a manufacturing flaw in the spring. The low pressure iscaused by the spring collaping inside of itself, and the high pressure is caused by the spring twisting and holding the diaphram in the closed position.

Now, the question still remains, if you do have the system with out the return line, then where does the fuel line off the diaphram go to? It has to go somewhere.

 

[n0xdw]

It is the supply!

the ones that have a pressure regulator have a separate line. The line from the regulator is return, but with the damper it is the source. Because i did not like a returnless system that does not compensate for pressure drop across the filter and it would have been quite difficult to set up a regulator at the tank to do that i replaced the fuel rail on my engine with the one from an earlier engine and modified a regulator to get the higher pressure the 99 and up system uses.

On the 99 and newer they did not drill the boss for the supply and simply put it in where the damper is.

 

[Diff Whack Daddy]

Ahhhhh. the light bulb has flashed brightly above my head and I stand corrected.

however, I still think that the problem lies in the device that is controlling the fuel pressure, which in this case would be that part of the in tank sending unit.
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[travlr]

On the subject of fuel pumps, prices for my '95 XLT range from $50 to $250.

Are after market brands ok?
Or is it wiser to use OEM in this case?

I found one at GenisisAuto-fuel_pump for $47.00.
The one at RockAuto-fuel_pump is $88.00.
The cheapest OEM is around $150.00.

Thanks,
~travlr

 

[n0xdw]

Ahhhhh. the light bulb has flashed brightly above my head and I stand corrected.

however, I still think that the problem lies in the device that is controlling the fuel pressure, which in this case would be that part of the in tank sending unit.
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Have you had a gauge on it to verify what the pressure really is doing? When you replaced the pump assembly it should have come with a new regulator.

 

[Diff Whack Daddy]

rickpotz, correct me if I am wrong, but you have only replaced the fuel pump, not the entire in tank unit?

 

[rickpotz]

Hey everyone,

Thanks for your input! I really appreciate it.

I believe I found the problem. Sorry I haven't written back but I've been out working on my car all day trying to resolve the issue. When I came in last night and the night before, I was dead tried.

First, just for your information, I found out that my engine is a SOHC.

Second, I believe my pump assembly filter was clogged!
My best analysis is that my fuel tank is bad.

On previous fuel pump replacements, there were fine particles in the bottom of my fuel tank but I didn't think much about it. I just thought it was due to dirty gas. That's the reason for the filter on the fuel pump assembly right?

This time the particles were more noticeable.
So, I tried to figure out where they came from.

I high pressure washed the inside of the tank and rust and particles just came flowing out. I was amazed.

I then went to a junk yard and inspected a similar tank. It was like night and day. My tank was rusting out from the inside. Soooo, I replaced it.

For others with problems, here are a few helpful things to help diagnose pump problems. You can measure voltage at the tank. It should be around 12 volts. Mine was a little lower. If you see a voltage drop when the pressure drops, you have a voltage problem. You can also test for voltage at the inertia switch.

Thanks again for your feedback and imput.
Rick

 

[n0xdw]

thanks for the update. I was working off the pic that was of a OHV... however with the additional information a question comes to mind. Have you ever filled up with E-85? If so don't! If you have a metal tank without a liner it will cause rust and corrosion. Glad you got it!
Good work!

 

[95exploresport]

This post has been helpful as I had the same problem of no power going up hills and it falls flat when I floor it. I just checked the fuel pressure and it reads 30 psi ignition on not running, 38 psi engine running. Now the question I have is what should the pressure be? I have read mixed answers on this ranging from 30 psi to 75 psi so I need a expert to let me know. *Engine specs below.
Also is my FPR in the tank or on the fuel rail passenger side.

1995 Explorer sport 4.0 liter 92,587 miles

 

[chuckthemadman]

po171 and po174 are not codes you should ignore they are telling you that your air fuel mix is not right this is pretty common among 4 wheelers because slinging mud every where will some times clog o2 sensors i believe you have been looking in the wrong area entirerley i think you should be checking your o2 sensors ,mass air flow/maf or manifold absolute pressure/map

 

[Tbars4]

po171 and po174 are not codes you should ignore they are telling you that your air fuel mix is not right this is pretty common among 4 wheelers because slinging mud every where will some times clog o2 sensors i believe you have been looking in the wrong area entirerley i think you should be checking your o2 sensors ,mass air flow/maf or manifold absolute pressure/map

..To whom's post are you answering?

 

[queen-latifah]

I am about to pull my hair out over this issue! Would someone please tell me if it is truly necessary to use a bronze tipped fuel pump rod if converting from a stock flat tappet cam, to an aftermarket roller? I have asked many sources, and I get both yes and no. I'm wondering why there appears to be no authoritative answer to this question? Here is what I'm working with. Standard (post '87) 350 shortblock with a Vortec full roller conversion. My bumpstick is GMPP #14097395. The manufacturers literature says NOTHING about using a bronze tip fuel pump rod to protect the cam lobe, however, I've read/heard about this being necessary to keep the lobe from being "chewed up" by the OEM steel pump rod. I have the original steel one, and a brand new Comp Cams 4607 as well. Which should I use? Oh, and lest I forget to ask, do I need to change the distributor gear too? It is the stock unit that came in the original (flat tappet) engine.