Running only the hp rail pump.

[purplepeopleeater]

Hello every one. I was wondering if anyone knowns how would running just the high pressure rail pump without the in tank fuel pump would work out. I recall someone saying it would work fine with the 2.9l, But if you were to run out of gas you would have to pressurize the tank. Thank you for any input.

 

[RonD]

Yes, what you said, in tank pump would need to be removed and tube extended to the bottom of the tank
Then you would need pressure in the tank that would push gasoline up and over the top of the tank to start the Siphon that feeds the HP pump.

Not sure if HP pump could create enough suction to start the siphon, if tank was full to the top it wouldn't take much to start it flowing

And yes, if you ran the tank dry or lost the siphon then you would have to get it started again

Might be able to siphon thru the low pressure pump, but can't say for sure if it would work at all or have enough flow for higher engine demand

Just getting an in tank HP pump would be a better solution in the long run, ditching the HP frame rail pump

 

[rusty ol ranger]

The lift pumps are like 25 bucks. Just replace it lol

 

[purplepeopleeater]

I already have the hp pump on the tank from a 92 ranger 2.9,but it starts acting up once I drive for about and hour. It starts idle I g rough and popping then has no power to even move off the road. I’ve relocated the tfi module with a heat sink and heatsink compound. and I’m getting kinda sick of pulling the bed to get to it. I was hoping to ditch it and make life easier to replace it. But it does seem to be more trouble then it’s worth. Thank you for the quick reply and help. You guys are awesome


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[alwaysFlOoReD]

If you already have a frame rail high pressure pump installed then I would buy a low pressure fuel pump and mount it somewhere on the frame between the high pressure pump and the tank. I'm not sure if it would pull thru the old in tank pump but it's worth a try in my opinion. If it doesn't pull thru the old in tank pump then I would remove the pump and extend the line to the bottom of the tank.

 

[bobbywalter]

you can just run the rail pump like ron outlined but there are times of air off concern when low on fuel....cant see any issues with a 2.9 though for normal use..

are you having contamination issues? are the wires getting restive? might just need fresh connectors/wire.

 

[purplepeopleeater]

That’s kinda what I was thinking. Just taking my out the pump in the tank and adding enough fuel line to make up for the missing 3 or 4 inches the pump took up. I replaced the high pressure pump on the frame along with the high pressure in tank pump. But that seemed to make my issue worse. What would take an hour of driving started showing up after 20 mins. I think they were fighting each other though.


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[purplepeopleeater]

Thanks for the ideas Bobby, the whole sending unit and wire are only a few months old and the pump is even newer that. I did have to put different connectors on the make the pump work, but haven’t looked at them since I put the new pump in. Contamination could be a problem too, though I’m not sure what could have gotten into there


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[RonD]

A blocked fuel line would show up alot faster than 45min-60min

You can't run two HP pumps on the same line, well you "can" but it won't work well, lol

If you have an HP pump in the tank then bypass frame rail pump and just run to fuel filter

Some dual pump setups also had a Reservoir in between tank and HP frame rail pump, that should be removed if using HP pump in the tank

Since you have already got the in tank HP pump then I would run it

Tank/HP pump------------------filter---------------engine

And thats all that should be on that fuel stystem

It is a 30psi system, but you can use barbed fittings and high pressure fuel line to put the system together

 

[adsm08]

There have been a couple people who have tried to run just the HP frame pump and leave the tank pump in place. The general experience seems to have been that when not running it creates too much of a restriction. The engine can run, but the frame pump has a hard time pulling through it and does not deliver enough volume.

 

[purplepeopleeater]

Well, I got bored and decided to give it a try, I removed the pump in the tank that i suspect to have a problem and placed a fuel line with the strained attached to it in the pumps place. I got rid of the canister filter thing some time ago,. Now I have the high pressure rail pump taking fuel from the tank to the filter and to the engine. Haven’t tested fuel pressure yet, but it starts and rungs great with little more then 1/4 tank of fuel. I haven’t taking a real road test, lust around the block a few times. But so far it seems possible. I will update when I get to test more. Thank you to everyone on the input and very helpful advise.


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[bobbywalter]

There have been a couple people who have tried to run just the HP frame pump and leave the tank pump in place. The general experience seems to have been that when not running it creates too much of a restriction. The engine can run, but the frame pump has a hard time pulling through it and does not deliver enough volume.

you dont want the tank pump for sure.


i have volume tested the oem style frame pump thoroughly and that pump feeds a 250 hp 302 with no issues just pulling out of the tank with a carb sock setup. it is my standard external fallback pump in an emergency or when i am trouble shooting with separate known good fuel supply.....anything more for loaded applications and you need a t rex type setup. so no worries there...save for off roading could bring issues when low on fuel.


but, running a high pressure into a high pressure will cause some cavitation and airoff issues and vaporlock over a short time which sounds like whats happening...

the stock low pressure looks like many stock high pressure pumps and i did it on accident before.


but, at the end of the day, the best setup for most is a single in tank unit.