From: Stephen & Jeanne Keith (cckw@comcast.net)
Date: Tue Feb 17 2004 - 08:00:42 PST
The carb on an M37 "may" work on engine vacume. The M151 works
that way. If so, lack of vacume/leak would have an evvecr
Steve AKA Dr Deuce
----- Original Message -----
From: "Adams-Graf, John" <grafj@krause.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Tuesday, February 17, 2004 9:16 AM
Subject: Re: [MV] Carb Question
Corey: I forwarded your note to Steve Turchet, our "tech guy" for Military
Vehicles Magazine. I thought he might have some ideas to help you. Here is
what he said:
>>>Here's my best suggestion for Corey...
Since the pump seems to work when you manually push it down, check to make
sure the linkage is pushing it down when the carb is assembled.
Manifold vacuum doesn't have much to do with the accelerator pump output,
since the pump squirts fuel by mechanical pressure. A vacuum leak severe
enough to cause that problem would also make your engine idle VERY poorly or
even die.
Steve<<<<
Hope this helps you,
John A-G
Editor, Military Vehicles Mag
www.militaryvehiclesmagazine.com
-----Original Message-----
From: Military Vehicles Mailing List [mailto:mil-veh@mil-veh.org]On
Behalf Of Corey Elliott
Sent: Monday, February 16, 2004 5:10 PM
To: Military Vehicles Mailing List
Subject: [MV] Carb Question
What would cause my accelerator pump in my M-37 to not work? It is the
stock ETW1 carb.
I've just about got this truck running like she just came off the production
line and this is my last hurdle.
With the truck idling (finally a near perfect idle mind you!) and me hitting
the accelerator the truck just basically completely dies. It literally acts
like someone simply turned off the ignition switch. If I let off the
accelerator without holding it too long the engine begins running again. If
I gradually accelerate it does great.
I've been chasing the problem for 2 weeks now (went as far as pulling the
front back apart (pain in my rear) to verify my timing chain wasn't off a
tooth (it wasn't, a.k.a. much wasted time). I finally watched the orifice in
the carb throat where the pump ejects its fuel. It basically dribble down
the carb throat when you open up the throttle from idle. This told me it was
obviously not working correctly.
The carb was rebuilt two weeks ago and is basically a brand new carb that
has sat on a shelf for 50 years. When kitting it, I noticed the inside
looked like an NOS unit. I believe it may be.
If I pull the top off the carb and manually press the accel. pump down, it
shoots a nice stream of fuel into the throat. The stream actually hits the
other side of the throat with a bit of force! This shows my pump is good. I
seated the pump into it's cavity in the top plate of the carb and then
applied pressurized air to the orifice that runs there and about blew the
pump out and up my nose hole. It is very air tight, but still moves freely.
I'm pulling 16-17 pounds of manifold vacuum at idle and it drops
significantly when the throttle is opened up. This tells me there should be
plenty of vacuum to hold the pump in the up position, and the decrease in
pressure tells me spring behind the pump should push it down and squirt gas.
I'm going crazy.
There has to be a vacuum leak somewhere not allowing the pump to be fully
retracting and compressing the spring. Right?
Anyone have any repair ideas or further troubleshooting ideas?
Thanks,
Corey
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