Running rough

1950 - 1952, M38, questions, discussions, regarding anything related to the M38.
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Scott in NM
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Running rough

Post by Scott in NM » Sat Jun 08, 2019 5:06 am

Humming along nicely down the country road just enjoying the day and the jeep started running rough like it was running out of gas. Full tank, so not the problem. Suspect the fuel delivery system (fuel pump, clogged line, bad carb, etc) because of the low and uneven poser . Pulled fuel line at the carburetor and noticed that when cranked (ignition switch OFF) the gas came out of the line in spurts spaced about 1 second apart. I would have expected a constant flow. I haven't checked fuel pump pressure, nor pulled the top of the carb to fill the bowl and see how it does.
1. What else can I check to see if in fact the fuel pump or carb?
2. Vacuum lines don't seem to have problems, everything intact and secure, nor the heat riser under the carb.
3. Wouldn't expect ignition system, it fires right up and idles OK.

Inputs?

Scott

Ben Dover
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Re: Running rough

Post by Ben Dover » Sat Jun 08, 2019 5:45 am

Check your point adjustment.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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mdainsd
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Re: Running rough

Post by mdainsd » Sat Jun 08, 2019 9:40 am

Spurts every second or so is correct operation for the mechanical fuel pump on an M38.

After you check the points as Joel suggested, I would check into the condenser in the distributor. It is a critical part of the ignition system. a vehicle will often start and idle with a bad or failing condenser, but not perform well under load, like driving. While you are checking the points look carefully at them, See if one side is developing a peak (or pointed raise area) and if the other point is developing a pit that matches the peak on the other one. This is a way to see what the confessor is doing without test equipment.
1952 M38 (2X) 1952 M37 1944 WC51 1942 WC 56/57 1942 Script MB 2010 Gator

Scott in NM
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Re: Running rough

Post by Scott in NM » Fri Jun 14, 2019 5:59 pm

I'll check the condenser when I get a chance, may even have a spare. If it were points alone, I wouldn't expect it to run nice and then start running rough. Or is my thought process wrong? But as long as I'm down there, I'll take a look.

Ben Dover
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Re: Running rough

Post by Ben Dover » Fri Jun 14, 2019 10:24 pm

Could even be as simple as ignition cables not bottomed in the cap,or dirt or oil on Coil tower, Wipe the coil tower clean using a bounty towel with a bit of WD-40 on it. Could be water in the gas, try some dry gas.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

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