Delayed Fuel Supply Issue

Well, I assume it's fuel supply related, but that's why I'm here.  Runs great, but after going 70mph for about 20 mins it starts choking.  As long as I push the clutch in for a few seconds it will come back.  The longer I have the clutch depressed the longer it seems to go without choking again.  Initially, slowing down a few mph helps it last longer, but eventually even going 50 mph it will choke again.  The only thing that seems to help is pressing the clutch or stopping altogether to let it rebound.  I just replaced the fuel pump/sending unit and the ignition coil.  Yesterday I also noticed some gas pooling on top of the intake, so I'm wondering if it is a carb issue. Any ideas?

I didn't think of the fuel filter, so I'll replace that. I think it's attached to the carb in the picture below?


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That looks to be the fuel filter.

Did you change ALL the rubber fuel lines?
The outside of them can look good but insides turn to mush and slow or stop the flow of gas so change them ALL out.
The other thing to try is removing the the gas cap(s) and see if it dose it. If it stops then the cap is not vented.
Dont so both the rubber lines & cap because if it does not do it you will not know what one is the cause.
Dave ----

Yes, that is the fuel filter. My truck had the exact same symptoms and the fix for mine was the fuel filter, once I figured out which one of the four filters I have on my truck was the culprit.

Ok thanks, I'll try the cap first then, since that would be the easier solution. The tank has what I thought was a vacuum line coming out of the top, but if you're saying the capnshould be vented then what is that line for, more venting?

I missed your comment, Frank, that sounds promising, thanks. I'm assuming mine doesn't have the other 3 filters yours does based on the shop manual illustration and following the fuel lines from front to back.

Be careful. Those filters on the carb strip easy.

That would be correct, I added the extra ones due to an extremely dirty rear tank.