Fuel pump

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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m38a1butch
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Fuel pump

Post by m38a1butch » Fri Mar 23, 2018 9:59 am

my m38a1 used to start fine but lately I've had to use a few shots of starter fluid to get it going. i'm not sure but i suspect the fuel pump. i notice the fuel pump has a long lever attached to it -- what's the purpose of this lever and how is it used? if it is a fuel pump problem would a fuel check valve between the pump and the carb help? is it difficult to rebuild a fuel pump?
USMC 1959 - 63
--------------------------
1952 USMC M38A1 MD delivered 9/52
1952 1/4 Ton M100 trailer delivered 9/52
1968 USMC M274A5 (now resides in the National Vietnam War Museum in Weatherford, TX -- RIP Francis)


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Scoutpilot
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Re: Fuel pump

Post by Scoutpilot » Fri Mar 23, 2018 11:24 am

If that long lever is a flat plate, then it is likely the manual primer handle. Raising and lowering it (pumping it) should fill the bowl in the carb. Just to be on the safe side, when you next check your oil level, smell the oil. If you detect a gasoline smell then the fuel pump diaphragm is likely cracked or the diaphragm stem seal is cracked. You can rebuild it yourself as long as you have the correct kit, a wide, clean workspace so you can organize the parts. You should take pictures as you are disassembling because it goes back together successfully only one way. If you have a reasonable level of skill, you should able to get it done in about 6-8 hours. You can get excellent quality kits from http://www.then-now-auto.com. You must be ready with the pump model number and the style of diaphragm shafts installed.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

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m38a1butch
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Re: Fuel pump

Post by m38a1butch » Fri Mar 23, 2018 1:42 pm

Scoutpilot wrote:
Fri Mar 23, 2018 11:24 am
If that long lever is a flat plate, then it is likely the manual primer handle. Raising and lowering it (pumping it) should fill the bowl in the carb. Just to be on the safe side, when you next check your oil level, smell the oil. If you detect a gasoline smell then the fuel pump diaphragm is likely cracked or the diaphragm stem seal is cracked. You can rebuild it yourself as long as you have the correct kit, a wide, clean workspace so you can organize the parts. You should take pictures as you are disassembling because it goes back together successfully only one way. If you have a reasonable level of skill, you should able to get it done in about 6-8 hours. You can get excellent quality kits from http://www.then-now-auto.com. You must be ready with the pump model number and the style of diaphragm shafts installed.
Thanks for the response
USMC 1959 - 63
--------------------------
1952 USMC M38A1 MD delivered 9/52
1952 1/4 Ton M100 trailer delivered 9/52
1968 USMC M274A5 (now resides in the National Vietnam War Museum in Weatherford, TX -- RIP Francis)


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