Gents:
First off before I started this repair/upgrade, my jeep ran and started OK, but the accelerator pump was weak, so I bought a Carb kit, a friend familiar with these installed it, so I don't know what went on there but he operates a reputable garage in town, good mechanic. In the mean time I bought a fuel pump rebuild kit and installed that. Hooked up the system, the primer on the pump works and I was able to pump fuel to the carb. This is a 1952 model so it has the fording kit installed. My problem is that I can not get the jeep to start, it will fire if I shoot starter fluid in the inlet but it won't stay running, so, no gas to the carb is my guess. What am I missing, thoughts on places to look that I've overlooked.
Thanks
M38A1 Fuel issues
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- G-Major
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Re: M38A1 Fuel issues
Probably should've verified the engine would start and run normally after installing the carb kit --- before touching the fuel pump.
Now you have 2 possible issues (carb and pump) happening at the same time.
You'll need to figure out and isolate which one (or both) have a problem.
Did you test fuel pump pressure and volume output before rebuilding the pump? After?
The Army manual has the procedures and specs, including how to pre-load the pump diaphram when assembling it so it'll pump properly.
Good luck!
Now you have 2 possible issues (carb and pump) happening at the same time.
You'll need to figure out and isolate which one (or both) have a problem.
Did you test fuel pump pressure and volume output before rebuilding the pump? After?
The Army manual has the procedures and specs, including how to pre-load the pump diaphram when assembling it so it'll pump properly.
Good luck!
Ron D
1951 M38
1951 M100
1951 M38
1951 M100
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- G-Corporal
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Re: M38A1 Fuel issues
Howdy all,
Update:
I checked the fuel pump and volume and pressure seem OK, did not put a gauge on it but looks OK. I pulled the top off of the carb and there is no gas in the bowl. Bear with me as I try to explain, when I hold the top half of the carb as it would sit on the carb body, with the float assembly in place, the needle is still fully engaged with the seat. It appears that the spring that is inside the needle is holding the needle into the seat. My understanding is that in this position the float should be low enough that the needle moves away from the seat to allow fuel into the carb. When I measure the float location, with the carb body upside down (this puts the float in the full bowl, closed needle valve position), the top of the float is 9/16 inch below the carb top casting. Do I need to adjust the float position? If so what are the correct dimensions?
Thx
Update:
I checked the fuel pump and volume and pressure seem OK, did not put a gauge on it but looks OK. I pulled the top off of the carb and there is no gas in the bowl. Bear with me as I try to explain, when I hold the top half of the carb as it would sit on the carb body, with the float assembly in place, the needle is still fully engaged with the seat. It appears that the spring that is inside the needle is holding the needle into the seat. My understanding is that in this position the float should be low enough that the needle moves away from the seat to allow fuel into the carb. When I measure the float location, with the carb body upside down (this puts the float in the full bowl, closed needle valve position), the top of the float is 9/16 inch below the carb top casting. Do I need to adjust the float position? If so what are the correct dimensions?
Thx
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- G-Corporal
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Re: M38A1 Fuel issues
I thought of a simpler question: Should the needle disengage from the seat when the float is in the lowest position, indicating that the bowl is empty of fuel?
- Scoutpilot
- G-Lieutenant General
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Re: M38A1 Fuel issues
The float setting for a YS is 1/4" as measured between the float and the top when inverted and no gasket in place.
'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
(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
- dpcd67
- G-General
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Re: M38A1 Fuel issues
Lesson #1: If you do not have ScoutPilot rebuild your carb, especially the vacuum operated ones on the M38/A1, and Dodge, you will have problems.
U. S. Army 28 years.
Armor Branch
Armor Branch
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Re: M38A1 Fuel issues
Thanks all for your help. Adjusted the float and she started right up. Good to go.
Thanks again.
Thanks again.
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