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rocky_lange 02-13-2011 12:59 PM

Fuel injected to carb nightmare
I recently bought a 91 Wrangler that a previous owner had swapped the 4 cyl EFI engine out with a 304 V-8 carbed engine. He half assed EVERYTHING and now I am playing a game of WTF???:banghead:

I ran well enough to drive home over 30 miles, but has sat until I was able to get a clean title before I started working on it. Now, she won't run. I am pretty sure that the original EFI fuel jump is still in the tank and is part of the problem. So, lets start at the tank and work our way forward. 1) EFI pump, 2) inline filter near tank, 3) mechanical fuel pump on engine, 4) inline fuel pump with return line, 5) screw in carb fuel filter, 6) 2 barrel carb.

3 filters?? Really??

So, I disconnected the fuel line between the inline and carb filters and NO fuel while cranking. The metal fuel line on the bottom of the engine mounted pump is slightly kinked, but not enough to completely block fuel flow. I also cannot hear the in tank pump running.

So, what should I do?

I guess the proper repair would be to drop the tank and remove the EFI pump and bypass that with a piece of fuel line, remove the existing fuel lines all the way to the engine mounted pump, run new line, replace the engine mounted pump, replace the kinked line with new and put in a new screw in filter on the carb.

That would work, but are there less intensive options?

Also, do I need to run a return line or is the psi low enough that there won't be a need?

uplifted 02-13-2011 01:13 PM

I'm still running the stock FI pump in my tank in conjunction with my carbed V8 without a single issue... been that way for 14k now... screw the mechanical pump, get rid of it.. You need to make sure that the intank pump is still there and wired.. disconnect a line and jump the fuel pump relay under the hood and see if it will start pumping fuel up...If it does all you need to do is rewired the relay for a key on, tap in a fuel regulator under the hood to knock the pressure down to 6psi and use the return line off the regulator back to the tank.. Very easy.. All i have in one inline filter at the carb, thats all you need.. Your first priority is to make sure the intank pump is there and works.. I can talk you through it on the phone if needed.

rocky_lange 02-13-2011 01:32 PM

I guess that makes more sense. I'll go out and check out my relays/fuses if I can find them.

89JEEPYJ 02-13-2011 02:02 PM

or u could jsut unplug the rear pump and run a power wire directly to it and cc if it turns on

rocky_lange 02-13-2011 02:21 PM

Well, I am guessing that the pump isn't working because the fuse relay panel under the hood is missing. Looks like I will have to hunt down a wiring diagram and find the wires to hot wire them at the pump. But again, if I have to drop the tank to get to the wires/pump, I am going to opt for the mechanical pump option.

uplifted 02-13-2011 02:34 PM

Yeah if the wiring has been butchered up then just stick with the mechanical pump.. Drop the tank , take out the pump if it's still there and add a small piece of metal line to make up for the pumps length.. add a my sock to then end of it to keep the heavy debris from entering... Then just run a stock mecanical pump off the block and call it a day..

rocky_lange 02-13-2011 02:38 PM

So run a larger steel fuel line from tank to mechanical pump. Do I need a return line with a mech pump?

uplifted 02-13-2011 02:59 PM

No need for a larger fuel line and no return line required.

rocky_lange 03-02-2011 02:26 PM

Finally had time to tackle the problem. I first removed the in line filter near the tank and replaced it with a Mr Gasket blue electric pump and ran new rubber hose to the carb inlet with a new filter on the carb as well (bypassed the mechanical pump and no return line). Still no go juice. So down came the tank. The person who dropped in the engine did remove the EFI fuel pump from inside the tank and put in a piece of rubber fuel line and some type of filter screen. However, it failed and corroded on the inside causing a complete blockage. So, replaced the screen and hose with a slighlty longer piece of hose and a brass t fitting allowing 2 inlets to the pick up and installed an inline filter at the new electric pump location. Turned the key and let it prime, but soon fuel was pouring out of the carb onto the engine. No good. Okay, easy fix. Back under the Jeep and removed the electric pump and put in a piece of rubber hose using the factory steel lines and re hooked the mechanical pump.

SHE RAN!!! :dance:

Briefly :nonono:

I think she is flooding. I guess I am going to have to put a return line on her somewhere.

Undead-89 03-02-2011 02:31 PM

Is the float working/adjusted properly in the float bowl? It should shut off incoming fuel on it's own.

rocky_lange 03-02-2011 02:43 PM


Originally Posted by Undead-89 (Post 1092451)
Is the float working/adjusted properly in the float bowl? It should shut off incoming fuel on it's own.

The jeep ran fine when I drove it home a few years ago. Sure, it may be gunked up from sitting but I want to try quick and easy before I rebuild the carb.

What I did find though, the AutuZone website has a fuel filter from a '75 CJ5 with the 304 and it has 2 outlets. That is the way it was before I started fighting this problem, so I guess I will make a trip to the parts store and pick up a filter, some clamps and a short run of1/4" line(second filter outlet looks smaller in diameter than the inlet and main outlet).

rocky_lange 03-03-2011 12:57 PM

Its alive !!!

Finally! She will run, roughly though, going to run a can of carb/fuel injector cleaner through it.

2 little things made me pull my hair out. I need to remember K.I.S.S.. I kept over thinking the problem and over looked the obvious, and simplest, of problems. All it needed was the fuel tank pick up strainer. And while doing all the rest of the unnecessary things I tried, somewhere along the way, I crimped the steel fuel line at the bottom of the fuel pump.:banghead:

Now on to other projects......(and remembering K.I.S.S.)

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