Engine 85 CJ7, 258, Carb replacement

[Gdamitbob]

New to me 85 CJ7 AMC 258 i6 / 4.2l I6. Don't know much about the history. Seems like everything on it has been modified or messed with in some fashion. Couldn't get it to idle without having the choke all the way out, even then it was rough. After looking at it I realized most of the vacuum lines had been abandoned but all of the emissions and air breather pieces are still there. I've replaced the fuel lines, fuel filter and necessary vacuum lines. I'm concerned that the electrical system is shot or not operating correctly since none of the sensors were connected. Should I bypass it altogether? Am I better off ordering an older style fully mechanical carb or should I order a rebuild kit for the Carter that's on there? My goal is to get it running well enough to idle so I can move it around the yard and diagnose any other potential issues.

 

[Gdamitbob]

I should have also noted the following:

-Fuel was coming out of the carb when the engine was running
-Fuel pump has not been replaced. fuel lines going to the rear have been replaced.
-Gas is possible bad, haven't had a chance to syphon. Can't tell how much is in there due to faulty gas gauge.

 

[CJ]

If fuel is being pushed into the carb while running that means the float valve is old and leaking. It (the carb) definitely needs to be rebuilt. The good thing it is pretty easy.
That's what I would do first. Most likely will fix the majority of your issues.
Also, you cannot make any tests with bad gas. Just take a gallon or two portable tank with an electric pump and bypass all your bad stuff.

 

[jzak]

Buy an $10 electric inline fuel pump, fill a gas can, and hook it to the carb. If that fixes the idle problem, then focus on the pump, clogged line, sending unit, bad gas, or rust in the tank. I wasted a lot of time and money rebuilding my TBI, only to find out it wasn't the problem. Good Luck!

 

[CJ]

Buy an $10 electric inline fuel pump, fill a gas can, and hook it to the carb. If that fixes the idle problem, then focus on the pump, clogged line, sending unit, bad gas, or rust in the tank. I wasted a lot of time and money rebuilding my TBI, only to find out it wasn't the problem. Good Luck!

Kinda what I said HERE.

Also, you cannot make any tests with bad gas. Just take a gallon or two portable tank with an electric pump and bypass all your bad stuff.,

 

[Gdamitbob]

If fuel is being pushed into the carb while running that means the float valve is old and leaking. It (the carb) definitely needs to be rebuilt. The good thing it is pretty easy.
That's what I would do first. Most likely will fix the majority of your issues.
Also, you cannot make any tests with bad gas. Just take a gallon or two portable tank with an electric pump and bypass all your bad stuff.

I already have a carb rebuild kit so I can work on that. Is there somewhere I can find a step by step to using the electric pump and where to bypass? Unfortunately, I don't have much experience working on mechanical engines but I'm willing and eager to learn.

 

[Project86]

Wouldn't be nice if someone had the measurements to make an access hole to the fuel sending unit? With the measurements you wouldn't have to drop the tank for an inspection.

Measure twice and your mileage may vary. Good luck.

 

[Griffin6]

What an absolute great idea. Thanks for the pictures and post!

 

[TSB8C]

The access opening in the floor over the fuel tank with a small panel screwed over it was a no-brainer for me. Second CJ I did this on.
Fuel tank access panel in floor

 

[CJ]

I think we are moving away from your initial post.
Let's get the CJ running.
Rebuild the carb.
Use fresh gas.
Enough said...

 

[Gdamitbob]

Buy an $10 electric inline fuel pump, fill a gas can, and hook it to the carb. If that fixes the idle problem, then focus on the pump, clogged line, sending unit, bad gas, or rust in the tank. I wasted a lot of time and money rebuilding my TBI, only to find out it wasn't the problem. Good Luck!

Do you have an example of an inline fuel pump that would work for this application? I tried googling and I'm getting a ton of different things pop up.

 

[CJ]

If you google its expensive. Just use a gallon tank with a cheap auxiliary fuel pump and make your own.

 

[Gdamitbob]

UPDATE

-Carb has been rebuilt. Unfortunately, I think I screwed it up. Further explanation below.
-Dumped all the gas from the tank, roughly 4 gallons. It had expired some time ago. Put in 5 gallons of fresh gas.
-Have inline pump to perform bypass.

I've attached several photos and a video that include what the carb looked like before I pulled it off the motor and what it looks like now. I think I installed the choke operating linkage, fast idle rod or the acc pump rod incorrectly, not sure which but something definitely doesn't seem right. I tried to follow the Limited instructions that came with the rebuild kit but that was a struggle. I noticed when I removed the carb from the engine, the choke linkage wasn't right and one of the sensor's wasn't connected to anything and the other end appears to be missing. Additionally, both adjustment screws were turned all the way in when the carb was first removed. At this point I'm kind of lost and would appreciate any constructive feedback to get going in the right direction. Thank you for all of your help so far.



























View attachment JEEP-Oct202025%2011_02AM-14413390.mp4

 

[Lumpy Grits]

I strongly urge you to buy a copy of the REAL Factory Service Manual MR-252.

 

[CJ]

I strongly urge you to buy a copy of the REAL Factory Service Manual MR-252.

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