surging

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Kurt Lesser
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surging

Post by Kurt Lesser » Mon May 02, 2016 8:03 am

I had the jeep out the other day after spending some time repairing the intake system and cleaning up the carb. I had an intermittent leak on the PCV valve due to the flare to NPT fitting being gone altogether but that's been replaced and as far as I can tell with some ether I have no other intake manifold leaks. I've also replaced the fuel lines and filter. Fuel pump pressure is steady at around 4 psi. What I'm seeing as I drive is in second gear I don't have smooth engine operation but it tends to surge at low speed. Is this something others have seen and corrected? Any suggestions appreciated.

Thanks,

Kurt
KG6KMJ
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab


Rickf
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Re: surging

Post by Rickf » Mon May 02, 2016 9:46 am

Is this at steady throttle or during acceleration? During acceleration the accelerator pump diaphragm will bottom out on the power valve if you hold it at a high enough throttle long enough. There will be a noticeable surge when the valve opens especially in the lower gears. If it is just at a cruise speed check for a bad ignition condenser if you have points and and naturally the point setting. Other than a float setting adjustment the carb will not generally cause that but a intake vacuum leak will.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Kurt Lesser
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Location: San Jose, Ca
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Re: surging

Post by Kurt Lesser » Mon May 02, 2016 5:50 pm

Rick,

I set the float when I cleaned the carb, I believe it was set at 7/32" with the gasket in place. Filter is new, electronic ignition, new plugs. Surging happens after shifting to second gear and then trying to maintain a steady speed. I will go back over the intake with some starting ether again and see if I pick anything up there.

Thanks,

Kurt
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab

Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5911
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: surging

Post by Rickf » Tue May 03, 2016 6:08 am

I have found carb cleaner and having the hand throttle set up to pretty high idle is the best combo for finding manifold vacuum leaks. the ether evaporates to quickly where the carb cleaner runs around the manifold. Very important to get to the underside of the manifold since that is where the leaks usually are.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone


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