Fuel system...

jeepin916

Active member
Ok all, i have it together. a carbed 350 TH350 trans with HP clutches and band, and shift kit, AA t-case adapter, now how do i go about hookin gup the fuel system?
its a 97 TJ and it has the stock tank and electric in tank fuel pump how can i adapt that to the mechanical fuel pump on the 350? is there a kit to switch everything? or do i have to rig something together? all input will help. thanks alot everyone, ken
 

So you want to use both the pump in the tank and the one on the engine? If you want to use just the one in the tank, simply remove the mechanical on on the engine, and you can get a blank cover to plug the hole in the side of the block.

If you want just the mechanical one on the engine, remove the one from the tank and put in a fuel sending unit for a vehicle that did not have the electric pump.

You could also put an electric pump out side of the tank (probably somewhere on/in the frame rail) and eliminate both of the other ones.

So, does that make sense at all? Hopefully it did! Let me know if you have any other questions
 

RE: 4.0 Rebuild Kit?

you can get the engine cover plate at autozone for a few bucks.. just bypass the mechanical pump altogether... you'll be making more than enough pressure that way... you might even want a regulator to keep it at about 6psi or less
 
RE: thanks for the positive comments on the Rubi

i wanted to use an electric pump but i didnt know that the pump in the tank would work with a 350. i was thinking that the PCM ran the fuel pump and since im taking out the PCM the pump wpuldnt run unless i riged it up. i guess i could rig it up but i didnt think it would have been a good idea. but if everyone thinks thats ok then i will go that way. thanks everyone for the input
 
RE: unlimited ?

AHHHHH. answer me this hehe..... on my TJ it has an electric in tank pump. now im not an expert with jeep electrical and why everything works the way it does, but i know that on a BMW, the fuel pump only runs when the engine computer sees engine RPM. Now on a BMW when the computer sees engine RPM it then triggers the fuel pumps to keep pumping.

NOW... if i put in a 350 in my TJ the computer will be disconnected and removed, so if my jeep fuel system runs off a system like this or similar then the fuel pump wouldnt work if the PCM is removed. any ideas on an alternative to fixing this? or maybe some info on how the fuel system works in my jeep will greatly help me in my project
 

I was told once (because I am looking into putting a carbed V8 in my 97) that the stock fuel pump in the 97 fuel injected runs about 30psi for the FI system, and a carbed system only needs 5-8 psi. I was told the stock pump would not work on a carbed system.
But please check it out yourself before trying....it could have been false info.....better safe than sorry
 
hmmm thats interesting. i know it runs higher Fuel pressures but i didnt think it would really matter, but im jsut hinking about putting in a fuel cell in place of the fuel tank and running an electric pump externally with a regulator but im just worried about having to run all that fuel line
 
RE: When did I become a

question: (thinking out my a$$ here)
If an external electric FP was installed under the hood, and the pump in the tank inhooked from the electrical system...would the new FP pull enough vac to pull gas through the old FP in the tank?

If so you could use exsisting plumbing.
 

putting an electric fuel pump in the engine bay is not a good idea... you want it back along the fuel rail to avoid vapor lock

as far as the pressure being too high.. you can always use a regulator.. and/or run it at constant ignition power with a pressure cuttoff switch.... once the pressure reaches say 15-20psi (just a tossed in figure), the fuel pump cuts off... when the system bleeds back to around 10psi, the pump turns back on.. that way, the pressure always stays between 10-20psi.. and the regulator will not allow the carb to see more than 5-8 psi
 
hmm interesting. thats a good idea i can use an external pump and the existing plumbing hmm i gotta look into that thanks guys.
 
the best way to make sure the pump is only running when the engine is turning is to have it switched by an oil pressure switch...
 

RE: sony radio cj7

oil presssure switch? u mean the pressyre sensor? that goes to the pressure gauge? if thats what ur talkin about mine is mechanical not electric so maybe i was thinking of using the distributor or something like that to trigger th fuel pump to stay pumping, what do u think?
 
RE: water in transmission

That's a good idea Snitty. I think there's a few places to tap into the oil system (behind distributor, on block around filter). Put an electrical switch in one of those locations to send power to your fuel pump. That way it won't start until you have oil pressure and it would shut off if you lost oil pressure while running.
 
RE: last touchup to the ranks

jeepin916, you can get an external switch like harry described... you can use fittings to piggy back it from your pressure sending unit.. or like he said, there are different spots here and there that you can tap into... you can run power right from that.. or have that power a relay... either way.. that is likely the best way to do it
 

hmmmm thanks everyone, here is what i think i will do, let me know what you guys think, i will have an external pump hooked into the exixting fuel system, i will run that pump off of ignition on, that way once the key is on it will start pumping, i think that if i hook it into the oil press switch it may have to crank too long at start up before the pressure switch sences oil pressure, and allows the fuel pump to turn on and pressurize the fuel system, what do u guys think? thanks again
 
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