carb...am I annoying you yet?

Well....I was putting up posts about my carb overflowing out the top with gas a few weeks back. I took it off, then realized I could have possibly forgotten to hook up the pump diaphram arm. I put it back on, and it stopped leaking gas so I threw the air cleaner back on all excited that I solved it and it was stupid/simple. Even ran great a couple of times. Eventually, the air cleaner must have been soaking up the gas so I didn't notice, cause its happening again. Its running ****ty and within 30 seconds there is usually gas all over the carb and intake/exhaust manifold. Any ideas on what possibly could be happening? Again, I have a 74 CJ-5 258. It started happening so I rebuilt the carb...still happening so I bought a new carb proffesionally rebuilt. Its still happening. Not sure if its coming out of a gasket but there is gas on the top of the carb, so I think its coming out the top of the throat.

I didn't want to pull the carb apart because of that green paint they put on it so you can't return it once its tampered with, but screw it, I'm checking the float level tonight.

My brothers said it could be the timing? I don't see how though. Regardless, wouldn't gas just fall into the exhaust before it came out of the throat of the carb?

Thanks in advance

 

Too much fuel pressure?

 

Have you checked float adjustment...or the float could be stuck...or bad needle and seat...juat a few thoughts

 

I haven't seen your other posts. Do you have an electric fuel pump? An aftermarket/hi-perf mechanical pump? I'm thinking maybe too much fuel pressure. That's the only thing that I can think of that might overcome the valve on the float. What kind of carb is it?

 

Its a Carter YF carb. When I rebuilt the first carb, I am 100% sure that I set the float and float drop correctly and I used a new needle and seat. I havn't checked the new one, but I assume the proffesional is better then me. I will check it later tonight tho. I have a mechanical fuel pump and I believe its stock of a stock type rather then a high performance one. I do have a pressure gauge so I may also check the fuel pressure tonight too. The mixture being too rich would definitly cause the engine to run erratically right? Its missing cylinders when it fires.

 

Oh, and the iginition coil blew up the other day, tho I assume thats unrelated. Don't know why it blew up but it might of had something to do with my sister installing it....

 

is the return line from the filter kinked or plugged?

 

Hmmm....return line? I'm not sure this has one? I don't elieve the pump has a return line and the filter is just and inline filter. Could this be the timing? I assume no?

 

u need a return line go to ur flaps an get enough line to reach ur tank, an a filter that has a return fitting on it. i had bout the same prob mine was flooding so bad it wouldn't run u put a return on it an it fixed it

 

HMMMMM, no return line on my 74 with the YF.......doesn't need one with a mechanical pump

 

rockstar offroad, sounds like I'll be trying that. I've already spent ridiculous amounts of money on other stupid things that didn't help. But it really shouldn't need that? The needle in the carb should block the gas, period. I think I'm going to give up on the almost running CJ5 to go to work on the nowhere near driveable M38A1 for the winter. Its atleast got a great 225 engine in it. Do you have a mechanical fuel pump rockstar?

 

if you dont have a return line, where would the excess fuel go?

 

yes its a stock 304 an after i did the return line it fixed it the 79 cj5 i had had a return line on it an it was a 258 should work the same on a 304 as a 258 mines just a bigger carb it will cost about 25-30 bucks to do

 

Your jeep never came with a fuel return line and does not need one, Your fuel pressure is regulated by the fuel pump. Your fuel flow is regulated by the float valve in the carburetor.
So what you need to do is determine that your fuel pressure is not too high before condeming the carb.
Also if you pinched off your fuel line so the carb would not get gas and the engine ran good untill the carb ran out of gas, this would eliminate any ignition system questions.
You can't stop now! We all need to hear what the problem is before next spring! Good luck, Greg

 

Thats true, I pulled off the fuel line and plugged it with a golf tee(buy a bag!) but I cannot remeber if it ran smooth or not? I have to do it again. I have a pressure gauge too but still havn't had time to hook it up. Oh how I long for the good ole days of just jumping in the jeep and going anywhere I want to. Rule of thumb between me and my friends, as long as the CJ runs, it dosn't get stuck...As long as the wrangler dosn't get stuck, it tows the CJ home. I guess if I have jeep time during the day, it will be on the CJ. Jeep time at night will be in the garage next to the wood stove, workin on the M38A1. The cutting and welding began last night!

 

So I finally tested the fuel pressure coming out of the filter. Its suppose to test between 4 and 5 psi. It tested 7 and a half. I never thought mechanical fuel pumps failed, but in the service manual it says if the fuel pump tests over 4 to 5 psi, it needs to be replaced. Would 7 and a half psi be enough to make the carburator pour out gas? And one more thing. the check valve thing that runs between the fuel tank and the charcoal box is not hooked up and never was. The lines to the tank are there but to the charcoal box, its clipped. This wouldn't have any effect on the pressure, right? So time to replace the fuel pump?

 

Or an aftermarket fuel pressure regulator. Cheap enough and often used for curing carb problems rough trails or steep slopes.

But I'm not certain the pressure is your problem.

Pete

 

My money is on the float binding up at the top...

 

You know I don't have that bad of a problm like his but I do have a large fuel smell while driving. I mean unburned fuel smell. It runs greta an all but I wonder what would be causing the what seems to be excess fuel. This is a overhauled motor and the carb was rebuilt as well. New mech. fuel pump, filter with a return line. plenty of air filter. I even updated the ing. to a Ford TFI. I own a 1975 CJ5 with the 304 and Motorcraft 2100 carb.

 

My book shows 3-5psi at idle. I don't know if 7 1/2 would open your float valve but is possible. Did you try clamping the line shut and starting the engine to see if it would run without leaking, then release your clamp to see if it floods again?
I don't want to say throw more parts at it, but it looks like fuel pumps are less than 30 bucks.
You said you do have a good fuel filter right? Could have junk from your fuel tank coming through the fuel line and holding your float valve open. I know, 32 year old jeeps shouldn't have any rust in the tank, but you never know
One time I had a intake valve spring brake on my AMC 360 in my jeep, I don't remember if it would blow gas back out my intake but I do remember it almost didn't make it home it ran that bad.
Good luck and keep us informed on your adventures.