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Vapor lock and charcoal canister

Joel Wilson

Joel Wilson

1/2 ton status
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I was doing some tinkering on the Jimmy and trying to think through my vapor lock problem and when it started. It could have started when I had all the soft lines replaced at the tank last time it was smogged. Return line for mechanical fuel pump is clear, checked with what was left from air compressor. So that isn't kinked. But maybe the one from vapor canister is. Or maybe canister itself is plugged. I will check the return line from canister tomorrow. 70$ to replace canister but I wonder, does it really help? Is it worth having? I know some carbs don't even have provisions for one. So could I just delete canister and plug off that port on carb? Then when I install new fuel filter with return, just use original fuel pump return line? Holley fuel pump has a built in regulator so just has a gozinta and a gozouta. Thanks in advance.

Joel
 
Vapor canister doesn't add or remove anything from heat soak hard start. You can remove it no big deal, maybe idle air adjustment after plugging port. It does help with the fuel odor while sitting in the hot sun.
What are the symptoms you are trying to diagnose ?
 
Wes Harden said:
Vapor canister doesn't add or remove anything from heat soak hard start. You can remove it no big deal, maybe idle air adjustment after plugging port. It does help with the fuel odor while sitting in the hot sun.
What are the symptoms you are trying to diagnose ?
Click to expand...
Before I left Cali, it was 115 that week. And the Jimmy would vapor lock at the same place going up the grade on hwy 36e. Give or take a mile. Even when I replaced mechanical fuel pump with an electric. Had to have it towed home 3x.
 
Wes Harden said:
Heavy load, heavy grade, low power, then dies, and won't restart ? Do I have that right
Click to expand...
I was running super unleaded too. I had a full tank on the valley floor and it vapor locked maybe 25 miles up 36e just past Paynes Creek where you start climbing
 
Are you sure it's a vaporlock issue?
I'm assuming you have a carburetor, from the mechanical fuel pump comment.
For sure no fuel in the bowl for no run/no start issue? Only happens after running hard up hill on the hwy?
 
Did it stall while pulling the hill? Then not restart? How long did you wait and still not get it to start, am assuming it cranked over well.
 
There are multiple ways to vapor lock.
A heat-soaked carburetor, solve that with a phenolic spacer. I've seen carburetors so hot the fuel is literally boiling in the bowl. Still running, but,not doing so well.

And, for heavens sake, make sure you cooling system is 100%. Cooling issues can cause a bunch of weird running problems.
Find where your fuel lines/hoses get close to any heat producing items. Heat socks are your friend.
 
An electric pump would more than likely solve any line/hose hose related vapor-lock problem.
So, that puts us back to the heat soaked carburetor.
Next time it quits, you need to see if 1. There is fuel in the bowl of the carburetor?
2. If so, is it boiling?
A can of Cosby sauce (read spray ether) will tell you next time it does it. When it quits, immediately, jump out, give e here a healthy snort of the sauce. If she fires right up, then quits again, walla! Problem found and solved. Phenolic carb spacer should fix you right up.
 
BoondocK5 said:
Are you sure it's a vaporlock issue?
I'm assuming you have a carburetor, from the mechanical fuel pump comment.
For sure no fuel in the bowl for no run/no start issue? Only happens after running hard up hill on the hwy?
Click to expand...
I have a spacer and I had no fuel at the fuel pump, mechanical or electric one I put in. I could get it to run with ether for a bit. Cooling system is good. Engine temps quarter the way up from cold on stock gauge and 190 on 2nd gauge sensor which is lower radiator hose. HD water pump, 4 row aluminum radiator, mech fan and shroud. Heat wrap on fuel lines from tank to engine, best I could.

This was a year ago, but I don't know what else it could be besides canister or a line at the tank
 
A line at the tank if cracked could allow air in.
Electric pump needs to be in the correct place to work. Esp if on steep grade. I had to move mine once going uphill on a 6%+ grade.
Also the pick up tube could have a hole uncovered at that lvl, maybe not big enough to starve the carb under regular driving. Possibly under heavy load high temps.
 
Just went out to double check a few things. There is a spacer, maybe half inch. Don't think it's phenolic. And where carb bolts to the intake, there is a small crack. Just noticed that. And if memory serves, the clear fuel filter was empty and while cranking after the stall, nothing was coming out that hose. But the fuel lines are wrapped.
 
This is the 1st position of the first electric pump. I had to move it down to the bottom hole on that grade I mentioned earlier. This micro pump failed after 6 months, and only had 5/16" hose nipples.
I now have a Holley 90 something gph pump with 3/8" hose nipples, in same location but even lower.
IMG_20231001_113434.jpg
Pictured is just below middle of tank
 
???? No, fuel in the plastic fuel filter !,!

Electric pumps push better than they.pull

If it was mine, the pump would be in the tank.... Pushing is more efficient, than a vacuum pump.

Do, back blow the lines....

Don't hesitate to check if tank vents are working.
 
CT-BLAZER said:
???? No, fuel in the plastic fuel filter !,!

Electric pumps push better than they.pull

If it was mine, the pump would be in the tank.... Pushing is more efficient, than a vacuum pump.

Do, back blow the lines....

Don't hesitate to check if tank vents are working.
Click to expand...
Okay, so if I gotta pull the tank to check the sock, which is most likely 46 yrs old, then I might as well replace sending unit which is also same age. While I am at it, upgrading to 31 gallon tank is not a bad idea either. Are there any fitment issues or anything else I should replace or look out for? I have the same fuel pump as Wes, but if I were to go in tank pump, what brand or model should I look for? Not against it, just wanting to weigh my options. I have changed an in tank pump and it was not on my fun list of things to do. That being said, I would have some sort of removable door to be able to change fuel pump in future. One more thing, is there a different filler neck I can get? One that you don't have to turn nozzle upside down so it doesn't shut off all the time?

Thanks
Joel
 
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