Vapor lock

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Vapor lock

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Vapor lock

Postby bobcat1/178th » May 30th, 2018, 5:33 pm

What's the best way to prevent vapor lock on mutts? My 151a1 had issues in 92 degree heat.....runs good until you stop and shut off engine....then don't want to run.....takes numerous starts to get running....
I'M going to start leaving hood up and may insulate fuel line.....

Make me wonder how they prevented this in vietnam..........
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Re: Vapor lock

Postby rickf » May 30th, 2018, 8:58 pm

A1's don't generally have a vapor lock issue because of the electric fuel pump plus the fuel line is nowhere near any heat. Are you possibly running an A2 fuel pump? If so they did have a return line for a vapor return on the 13660 carburetors. I have very seldom ever heard of vapor lock problems with them though. I set one up for the first cross country convoy and I eliminated the return line due to not having the correct steel lines and he had no issues at all even in 100 degree heat. That same vehicle has been on several of the convoys with no vapor lock issues and these are all slow speed convoys. If you are running the A2 pump you may have a failing fuel pump that is not moving enough gas to overcome the heat issue.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Vapor lock

Postby muttguru » May 31st, 2018, 3:08 am

rickf wrote: If you are running the A2 pump you may have a failing fuel pump ............


Or a failing Chinese chrome ignition coil..............the same symptoms....
Ken
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Ken

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Notes for 2018...... Doing nothing is ALWAYS an option !
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Re: Vapor lock

Postby rickf » May 31st, 2018, 7:43 am

True on the coil, if it continues to stall and no start then the coil can also be suspect. The coil will usually go out while driving and a usual symptom is that it will start to lose power and misfire and backfire out the exhaust as it starts to drop the spark and load up the exhaust with gas and then fire once in a while and light off the gas in the exhaust. BANG! It will quit pretty soon after that and then will not start until the coil cools a bit.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Vapor lock

Postby bobcat1/178th » May 31st, 2018, 1:25 pm

I have a elect fuel pump....most .everything is original to the A1 model.......the coil is original GI......

Was told running 87 octane ethanol added fuel could contribute......someone recommends non ethanol high octane.....but not sure that will help....I know in hot weather engine compart gets very hot...can fry eggs on trans/shifter cover......when driving I have no issue because there is more air flow through compartment.....
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Re: Vapor lock

Postby rickf » May 31st, 2018, 4:22 pm

Remember where the muffler is, right under the floor and almost touching it between the seats. The engine compartment of a mutt does not get very hot, that fan move a lot of air even at idle. The ethanol gas will vapor lock faster but again, your gas line is in the passenger compartment for most of it's run, only a real short section before it gets to the carb. I have run mine on 100 degree days with no issues whatsoever. Depending on where you are premium also has ethanol. Here in NJ all gasoline has ethanol. It sounds like you may have a clogged filter or a coil going out. Do you still have points? If so when was the last time you changed the condensor?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Vapor lock

Postby bobcat1/178th » June 2nd, 2018, 6:59 pm

No points....electronic....I'll check inline filter.......
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