Military-Vehicles: Re: [MV] M38 loses power, stalls

Re: [MV] M38 loses power, stalls

Alan Bowes (alan_bowes@phast.com)
Sun, 03 Aug 1997 21:43:37 -0600

SBJohnston@aol.com wrote:

> It was then that I noticed that the dip tube was jagged on the end, like it
> had been cut with the hacksaw instead of a tubing cutter. Then I measured
> how far it extended into the tank. Not far enough! I bet someone cut it
> short, perhaps to reduce intake of sediment (but it is *inside* of the filter
> -- so I guess I don't know why it would have ever been shortened). In any
> case, while I still had a 1/4 tank of gas, it was barely touching the surface
> of the fuel!
>
> Looking back on this madness, it looks like I fixed the problem but it may
> have had several causes: weak pumping action, semi-plugged filter, and
> perhaps a dirty carb. But running the engine so much for troubleshooting
> lowered the fuel in the tank so that I was running out of gas - sort of
> (thanks to the shortened dip tube). No wonder I was going crazy!

Hi, Steve,

Sounds like you're pretty familiar with the fuel system of an M38 by now.

I'd strongly suggest installing a good stock in-tank fuel filter. It can save you lots of
problems. It only takes one flake of rust or other crud to block a fuel line or to hold a
check valve open. The nice thing about having the filter at the fuel pickup is that the
crud never has a chance to get into the fuel line to clog it, let alone to the fuel pump.

I'll be overhauling the fuel system on my M37 pretty soon. It's kind of a mess...fuel tank
of unknown origin, cut fuel lines, hoses missing. I think I'll just start at the tank and
work my way forward. I have a good stock tank to put in, but I have to get a stock filler
neck assembly and the mounting brackets before I can install it.

Pat Patterson's suggestion to carry an electric fuel pump as a spare is a good idea,
though I would modify it slightly and suggest carrying an extra stock pump. I've been
doing this for years. I've only had to install one in the field a number of years
ago...but it was nice to have the stock pump, since I didn't need to cut any lines...just
used a half-inch socket and a couple of flare-nut wrenches. Ten or 15 minutes and I was on
the road again.

Back to the fuel pickup thing. Without a filter at the pickup, it is very possible that
debris was causing your pump to malfunction. Even small bits of sediment can hold the
check valves open.

Anyway, hope it keeps running well.

Alan

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