Gas tank swap from '91 4.0L to 87' 2.9L

[greaseandmetal]

I have a plastic gas tank pulled from a 91 4.0l that i want to put in my 87 2.9l. The 4.0l appears to have a single in tank fuel pump at 65 psi with 18 gph. While my 2.9l has an in-tank pump at 7 psi with 15 gph plus an in-line pump at 45 psi with 30-40 gph. Adding 7 to 45 yields 52 psi, which is 13 psi lower than the pump in the 4.0l fuel tank.

So question, do I:

a) Use the pump from the new tank and bypass my in-line pump, because the extra pressure won't hurt anything.

b) Try to put my in-tank pump from the 2.9l in the 4.0l tank.

or c) Go **** in my hand, cuz it just ain't gonna work.

Another factor to consider is i'm trying to get my fuel gauge working, I believe its the sender unit because I've tested the gauge itself. Plus the new tank is bigger and plastic so won't rust.

 

[oksleeper]

Go with the bigger pump the regulator will take care of the excess pressure

 

[echo]

I've done this already and have put a post about it on this forum. I think you'll find that the plastic tank rides higher then the metal one in the 87. You may have issues with it rubbing against the bottom of the bed. Either tank you can run your engine off of using just the in tank pump from the 91. I'm doing that in my 87 right now. Just pulled out the inline pump and replaced it with fuel hose. You can't swap sender units though. If you keep the metal tank issue it's sender unit but put the pump from the 91 on it.

 

[greaseandmetal]

Awesome, thanks for the info guys.

Will try to repair old sender unit, then check if the plastic tank fits. If it fits then I'll put the repaired sender unit on the new tank assembly.

 

[echo]

Just remember the sender unit from the metal tank won't fit in the plastic and vise versa. You've to use the sender unit that came with said tank. You can swap pumps if needed and the wiring connection is the same for both sender units.

 

[greaseandmetal]

So I'll have to swap my gauge if I use the new sender unit? I read the ohms are different and backwards. The new sender unit reads high ohms empty and the old one high ohms full.

 

[echo]

Not sure on that one cause I used the sender unit that came with my 87. Just used the newer pump.