Fuel pump

[usma41]

Wes, after all the adjusting on the float, I'v come to the conclusion that it was also the pump. I had installed a in-line filter, but stupid me put it after the pump instead of before it. After noticing the amount of fuel in the bowl of the in-line , it seems like it's not pumping enough. (only about 1/4 of the bowl had any fuel in it)

[usma41]

I also was wondering if any one knew the linkage for a manual primer on the fuel pump that I'm going to install. This pump was originaly on the jeep, but when I replaced it, I also rebuilt it.

[wesk]

Rich

You must have the correct pump case to use the manual priming lever. Since the Army dumped the manual priming lever pretty early on there aren't a lot of them to be had.

It is not uncommon for a sedimate bowl type filter to not be full while the engine is running.

[usma41]

I have one, it was the oringinal that was on the jeep when it was a rust bucket. As far as the fuel bowl go's I'm at the end of the line as to why this thing wants to keep stalling at a stop and a left turn. Usually, when I take the top of the carb off there's a full bowl of gas in it, but not recently, it's only half full.

[G740]

I beg to disagree with Wes on this one. About 90% or better of the M38's did not come out of the factory with primer levers. The M38A1, M37, M35 and most all the vehicles produced from 1952 had primer levers. If you are trying to be "correct" on an M38, you should NOT have a hand prime lever.
Filters. The common misconception with clear in line filters is that they need to fill up to be working is incorrect. They will typically not fill up. I can not explain why, it is just so. Your filter not filling is no indication of fuel pump performance. The only way to tell accurately is to put a fuel pressure gauge inline after the pump and check the pressure reading. It should be between 3-5.5 lbs.
Regards,
John

[wesk]

Hello John,
No disagreement. I've never purported the priming lever pump to be an original M38 item. All the manual research indicates the primer lever pump was a original G758- item.

[wesk]

The lever, it's seals and linkages are listed in the M38A1 ORD 9. I've never tried to put the lever parts in an earlier housing so can't say if they'll work in there or not. John Bizal may have an answer for that question.

[usma41]

I'll have to look it up, but I belive I seen this pump in my M38 maual, and like I said it was on the origenal engin when it was a rust bucket. If you go to my gallary you can see the contract number on the hood, this is also the origenal number because when it was sand blasted for some reason it had edtced it way into the steel. Also wes, is there a spell check on here? LOL

[wesk]

All of the M38 manuals and parts list only show the basic pump with it's vent capped with a breather fitting or with it's vent connected to the later M38 vent system. None show the lever primed pump.

These are the M38 illustrations:


The later M38 pump connected to the vent system


Early M38 pump with a vent cap on it's vent port.


This parts illustration is the same in both the 1951 and 1955 M38 ORD 9's.

These are the M38A1 Illustrations:


From the M38A1 Operator's & Maint manual


From the Sep 56 M38A1 ORD 9

[usma41]

Wes, you may be correct on this but everyone must relize that there was a lot of feild modifications on every vehical the military had. The m38a1 illustration you show may also applied to the M38 i.e. My M38 was delivered to the Army in Feb 52 and a friend of mine has a M38A1 that was delivered in Feb 52. So there was considerble overlap between the two.

[usma41]

P. S. to everyone, can we get back to the problem at hand. What is causeing this vehicale to increse RPM's on a left turn and decrese on a right turn to the point of stalling. Also on a stop it has a tendentcy to stall or have a drop in the RPM's , Float checked out OK, fuel pump OK?????????? Could it be linkage? Could it be electrical? What?

[wesk]

This web site not only helps address technical trouble shooting issues it also addresses restoration accuracy. We are all well aware that anything could have been put on the jeeps after they left the factory by anyone including civilian owners. When we ask what is correct then we must also state for what reason. IE factory as delivered resto, motor pool class and so on.

I am a stickler for details which is why we have these sites. They help with the hard to find details. It is my desire to make reasonably sure that data that appears here is explained well enough that it doesn't get mis-quoted later on.

With that said, I'll point out one more time for the masses:

The M38 did not come factory equipped with a priming lever on it's fuel pump. The M38 tach data and parts list do not show any fuel pumps with priming levers.

The early M38A1 came from the factory with a hand priming lever on it's fueel pump. The M38A1 tech data and IPL show this.

So if you have an M38 and want the correct fuel pump for a factory class resto the priming lever pump is out. If it is a motor pool resto or a driver then any pump that fits is in.

[wesk]

P. S. to everyone, can we get back to the problem at hand. What is causeing this vehicale to increse RPM's on a left turn and decrese on a right turn to the point of stalling. Also on a stop it has a tendentcy to stall or have a drop in the RPM's , Float checked out OK, fuel pump OK?????????? Could it be linkage? Could it be electrical? What?

Hello Rich,
The topic of engine changing RPM in turns was not part of this thread. Your thread you started to find an answer to that problem is titled RPM's and is further down this list. To get there quickly just click this link:
http://www.willysmjeeps.com/v2/modules. ... pic&t=1110