Re: [MV] HELP - Self Priming ??? M38A1 Dual Action Fuel Pump

Paul,

Great information.

I did not consider the check valves, in my attempt to eliminate the in tank
fuel filter. I will replace the in tank filter ASAP.

The flex line was replaced, since the old flex line was OK but old.

I did not consider the cam holding the actuating pump open.

Thanks all !!!

Tom


----- Original Message -----
From: "Paul Vandervort" <pgv@imaxx.net>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Thursday, September 02, 2004 4:40 PM
Subject: Re: [MV] HELP - Self Priming ??? M38A1 Dual Action Fuel Pump

[color=blue]
> Tom
>
> The manual lever should operate the pump just as in the normal camshaft
> operated mode. There will be a free area that the hand lever will move
> freely up and down in. This area of lever action will not operate the
> pumping action. You have to pull up fairly hard to actuate the
> diaphragm. You should feel the resistance from the spring loaded
> diaphragm. Note that if the cam lobe has the the internal arm lifted,
> the hand lever may not be effective, so you may have to rotate the
> engine slightly. It has been a while since I looked at this style pump,
> but the hand lever may override the camshaft operated arm if the cam
> lobe has the cam operated arm lifted, but currently I am not 100% sure.
> Pumps not pumping can be caused by:
> 1. Air leak in the suction line/hose. Almost any air leak between the
> tank and pump will cause it not to draw fuel. Pressurize the line back
> to the tank (with tank cap removed so you don't overpressurize tank) and
> look for leaks.
> 2. If you removed the intank fuel filter you run the risk of introducing
> contaminates into the fuel pump. ANY particles stuck in the fuel pump's
> check valve(s) will definitely cause it to not pump. If the inlet check
> valve(s) (total of three) get anything in any one of them it will draw
> fuel in but will push it right back into the tank, and thus will not
> produce any pressure.
> 3. Remove the flexible fuel line that runs from the frame area to the
> pump. Look inside and make sure that the line has no collapsed
> internally. Also if it still have the fuel shut off valve installed at
> the flex fuel line location, make sure it has no leaks.
> 4. Make sure the fuel tank is vented. If it is not vented eventually you
> will not be able to draw fuel from it.
>
> Also make sure that you don't have a leak in the pump's diaphragms and
> you are just dumping gas right into the engine oil pan. I have seen this
> before, but the pump would still produce enough pressure to run the
> engine.
> I had a '65 Chevy that would hesitate a highway speed. Would run in the
> lower bands fine. That was a bad fuel pump.
>
> Hope this helps ya, I hope I covered all the possibilities.
>
> Paul Vandervort
> MVPA 437
> IMVPA 007
>
>
> Thomas M McHugh wrote:[color=green]
> >
> > OK learned list, how about some help.
> >
> > Prior to stalling out, I had trouble accelerating to top speed, it[/color][/color]
seemed to[color=blue][color=green]
> > be starving. It seemed to run better with less throttle. Towing it[/color][/color]
at[color=blue][color=green]
> > speed suddenly caused it to start, with a pop, & then ran for a while &
> > slowly died out.
> >
> > Now it will not run.
> >
> > The Fuel pump was rebuilt last driving season & the Carb was rebuilt[/color][/color]
last[color=blue][color=green]
> > spring. Plugs are new, Points, Condenser & Rotor check out OK.
> >
> > I tried putting on an inline fuel filter & cut the old in tank fuel[/color][/color]
filter[color=blue][color=green]
> > off. It now is a straight open gas line out of the tank.
> >
> > I do not seem to be getting fuel & using the priming lever does not draw[/color][/color]
any[color=blue][color=green]
> > fuel. I have a hose into a jug off of the fuel pump to carb line,[/color][/color]
have[color=blue][color=green]
> > cranked it a lot, without fuel flowing.
> >
> > Should the priming lever draw fuel into the empty gas line in the gas[/color][/color]
tank[color=blue][color=green]
> > ???
> >
> > NOW: What should I do before I remove the fuel pump & look for a[/color][/color]
problem[color=blue][color=green]
> > ???
> >
> > As always, any & all help is appreciated.
> >
> > Tom McHugh, NJ
> > 1952 M38A1
> > M-416 Trailer
> > MVPA, MTA
> >
> > NOTE:
> > New Jersey State Commander
> > Korean War Veterans Association
> > "Always looking for Korean Vets to join the KWVA"
> >
> > If you served during the Korean War
> > OR
> > Served in Korea since the war, join the KWVA now.[/color][/color]

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