Topic: 4 banger transplant. Need some tech advice/info

[Backroads]

So you all think some sort of inline check valve should be installed on the supply line to keep fuel in the line after the initial prime...

What about FPR then? Adjust the stock one down and see where it ends up or just go with an adjustable right off the bat.

[sharpxmen]

So you all think some sort of inline check valve should be installed on the supply line to keep fuel in the line after the initial prime...

What about FPR then? Adjust the stock one down and see where it ends up or just go with an adjustable right off the bat.

the stock one is adjustable so you don't need another one. A Mallory for example would have a larger return valve and that would def work better to offload the extra flow but you can always add that later if you run into that issue.

[dwtaylorpdx]

First thing I'd do is see if I can blow air backwards through the pump,
What does the Rail check valve look like, I have a Regulator on the rail,
is the regulator acting as a check valve? Cause there is no other part on
mine that could be a check valve and the rail has nothing on it I've looked
through it before...

Yep I dropped some numbers on the math.

When you look the MPI
pump up on the NAPA web page its a similar style pump to the pics for the TBI pump.
I really believe you could simply shorten the pipe that eh MPI pump is hose clamped to
and install the TBI pump and strainer. The napa web page has a picture of the MPI
fuel pump and gauge sender assembly and you can see how it would work.

I think its a easy fix.

Dave

[sharpxmen]

nice work 

[Backroads]

Thanks for seperating, I guess I should still update here since I cant reply in the FAQ thread?

[Backroads]

Well I just dont get it 

'new' pump setup is in, new soft lines from the pump to the hardlines on the frame. Everything seemed kosher...but of course it didnt work!

I only put a few gallons of gas in it, because after all the siphoning of gas I've done through this whole ordeal is literally making me sick, I didnt wanna have to pump it back out!
Despite all that my fuel gauge is reading 3/4 of a tank!!!

So I found this statement in searching
'The fuel level range is different resistance so it will require some mods to make them read correctly but you should be able to use the assembly in the poly tank and make it work'

I'm guessing thats part of the problem.

Second, it runs like complete crap. It was running fine before any of this, it just leaked.

It started right up, but just runs really rough, if I give it throttle, it idles up but never really smooths out. Its kinda hot rod-ish.

I've got 2 sources to test before I'm officially out of ideas.

The tank I put in had 2 'rollover' check valves coming off of it with a vacuum line T'd between them. I ran that line to my evap canister. wrong?

MAYBE my fuel filter is clogged, or something. I can see it spraying fuel in the throttle body though so I dont know about that.

any ideas?

[sharpxmen]

i can think of 3 things
1. you mixed the pressure and return lines
2. your pump sits too low and pressed on the bottom of the tank and you don't get enough pressure
3. your return is too low in the tank and you get too much pressure

you can figure it out easily with a fuel pressure gauge, not sure if you have one

[Backroads]

i can think of 3 things
1. you mixed the pressure and return lines
2. your pump sits too low and pressed on the bottom of the tank and you don't get enough pressure
3. your return is too low in the tank and you get too much pressure

you can figure it out easily with a fuel pressure gauge, not sure if you have one

you make good points, and I thought about those. I verified via my manual that I do have the pressure/return lines correct.

I really hate the thought of dropping the tank again but I know these dumb plastic tanks like to warp and its possible it is hitting. What could I do about that though?

The whole assy shouldnt be any longer than it would have been with the stock HP pump I swapped out.

also..the tank I used doesnt have anything in it. Just bare bone empty plastic tank. The other one I have has sort of a 'tray' at the bottom below the tank...think that matters? I took the pump from the other tank and used it in this one...

[dwtaylorpdx]

I recently had to replace the pump in my 94 YJ and I had to shorten the pump hose
by about 1/2 an inch, I also drilled a hole in the return pipe because the rubber gadget
that it has on the bottom end can block it if the tank is too tight to  it.
You don't have to drop the tank to tell if the pressure and return are reversed,
just unhook the hose from the filter and turn the key on briefly, the fuel
should come from the tank not from the engine end.
(Be careful a LOT of fuel comes out, I use a hose into a can to catch the fuel...)

Dave

[sharpxmen]

rent a fuel pressure gauge, that will tell you for sure what's happening there.