Discussion in 'Early CJ5 and CJ6 Tech' started by nolehynaws, Feb 9, 2020.
Make sure the pump linkage hasn't come off of the shaft.
Yes! Could the distributor be the problem? I haven't done much with it.
Okay, where do I find that?
At the bottom of the carb. on the opposite side (right side) of the other linkage.
I was thinking maybe the condenser is bad, but I seriously doubt it since it seems more than a coincidence that the problem started after cleaning the carb. Generally the condenser just totally fails anyway.
I didn’t see anything like that but I’ll check again!
Hmm, well thank you for all the ideas! It’s been very frustrating trying to get this thing to work. But I’ll look at the stuff you said next weekend, and let you know if it’s still being stubborn.
View attachment 54788
I found a diagram for your carb (YF). It appears the only circuit that passes through the bowl where it can leak out when setting is the idle circuit.
Carter YF YFA Carburetor - Mikes Carburetor Parts
Read the above and make sure to get the metering rod set right.
Now to address the fuel leaking from bowl. Does it still do it when setting for a period of time since you rebuilt it?
If so when you get the problem fixed change your fuel contaminated crank-case oil!
For the fuel to leak out it appears the only passage (beside a cracked bowl (carb body)) is through the idle and/or accel pump areas.
If the engine backfired it's possible the pumo diaphram is split (check it closely). Other areas is the pump housing (carb body) to bowl gasket (which is actually the 'flat area around the pump diaphram), or the gasket between the carb body and the throttle plate (part with the butterfly and shaft).
In the cross section diagram the thick black line is the gasket that keeps fuel in the bowl.
While it's apart I'd inspect the area of the bowl where the accel pump housing screws are threaded. It's possible a too-long screw was used and cracked the bottom of bowl.
Any cracks or damaged gasket in this area can allow fuel leakage when setting and also allow air to enter (due to intake manifold vacuum) messing up air/fuel mixture to the point of starvation.
Wow, this is very informative thank you so much! I’ll check all this out this weekend and get back to you. And yes, it backfired when the timing was way wrong so maybe it’s the diaphragm.
Cleaned the carburetor again, and this is what’s happening now. At the end of the video I shut it off, it’ll stay going like that for a long time. Completely lost again. I replaced the diaphragm in the carburetor and this is still happening. There’s a small leak coming from where the throttle linkage connects to the carburetor, but I don’t know if this would affect anything or how I would even go about fixing it. This is very frustrating
And no, it hadn’t. Everything in the carb seemed to be fine! Thank you for all your help.
I’ll definitely replace the gaskets next. Would that also be the cause of what’s happening in this video?
Your video shows the engine "hunting." =Improper fuel/air mixture.
When a YF floods, it leaks under the center of the float bowl, flowing down the accelerator pump shaft where it penetrates through the bowl, then attaching to the throttle shaft.
If your leak is under the bowl like that, the carb is flooding. Wrong float level, dirty/leaky float valve, excess pump pressure, or some such. (Pump pressure should not be more than about 3psi.)
Be aware that Jeeps had a different float valve and float height specification than other YJ applications. Has a smaller inlet orifice, and a spring-loaded needle, to reduce flooding under rough conditions. It needs to be adjusted appropriately also.
Many generic rebuild kits do not include the right parts, and some rebuilders do not undertstand the different float height setting.
I got my YF specific kit from Daytona Parts. There are others specializing in these old carburators.
OldJeepCarbs.com for one.
Carter Yf Rebuild Notes
This was a nice set of notes on rebuilding a YF.
Okay I’ll mess with the float height, and how do you check pump pressure? And I’ll check the rebuild kit I used, maybe I got a bad one :/
Awesome, thanks! If I can’t make it work with the one I’ve got I’ll be ordering that.
Perfect, this is great. Thanks again!
Do you have a FSM?
Put a gauge on the pump output. Crank the engine a few turns.
It is also required to check adequate volume, by measuring flow into a cup with the line disconnected.
FSM has details.
Yep, I’ve got one. Thanks!
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