Re: [MV] M998 HMMWV accelerator problem

From: mblair1@home.net
Date: Thu Dec 30 1999 - 00:58:39 PST


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"James Shanks" <n1vbn@bit-net.com> wrote:
> >Hey, gang. I seem to have a problem with the accelerator and/or
> >injection pump on my new 1986 M998 military HMMWV with the 6.2 liter
> >diesel engine. The idle speed regulation is pretty poor; it'll idle
> >slowly, then sometimes surge a little, or sometime surge a lot and
> >then die. When I press the accelerator, there's a delay of a couple
> >seconds before the engine begins to pick up, and then when I release
> >it, there's a delay of a couple seconds before it slows back down.
[...]
> Yup!! It sounds like you have air bubbles in the fuel. This is caused by
> improper fitting fuel filters .....loose fuel fittings and holy fuel lines
> from the tank to the fuel pump mounted on the engine. It could also be
> sucking air thru the vent hole on the fuel pump due to a bad
> diaphragm.

Hmm, I replaced the fuel filter (see rant below) and bled it, and the
truck is still behaving the same way. So, you really think this
behavior could just be from air? I was ready to pull the injection
pump (it sounds so simple when I say it that way :-) and bring it
to the rebuild shop, but I guess I might as well spend another day
hunting for any more possible leaks and doing a really thorough
bleeding. Hmm, come to think of it, my 2.5-ton truck was always hard
to start after it sat for a week, even though I had bled the system at
the filters several times, but it has been starting quickly and
running just great ever since I did a thorough bleeding at the
injector fittings... Maybe that's all my HMMWV needs. Hope hope hope
hope hope...

After 12 years of aging and ham-fisted repairs, I don't like the looks
of a lot of the rubber fuel lines and lots of the hose clamps, so
maybe while I'm at it I might as well replace all of the
easily-accessible low-pressure lines and clamps.

In case I do end up needing to rebuild the fuel injection pump, I have
a question about removing it: The manual says to turn the engine in
order to be able to access each of the three screws on the pump's
timing flange through the oil fill tube hole. Being a neophyte
mechanic, I don't have the slightest idea of how to turn an engine
without turning on the starter, let alone doing it in a controlled
enough fashion to line up a screw with a hole... Does anybody have a
clue they could lend me?

Ok, here's my rant:

    Of all the STUPID places to put a &@^* fuel filter! That filter is
    a pain in the @$$ to change!! Ok, it's not quite as bad as the
    fuel filter on my 4Runner (I gave up on that one, and paid
    somebody else to replace it with the spare I handed them... it
    wasn't cheap, but knuckles don't always grow back... :-). Didn't
    AM General learn ANYTHING when they made 2.5-ton trucks? Those
    things are EASY to work on, but a HMMWV's innards are even less
    accessible that my &@^* compact import truck's innards!

I feel much better now. :-)

--
Mark J. Blair, KE6MYK <mblair1@home.net>
PGP 2.6.2 public key available from http://pgp.ai.mit.edu/
Web page: http://www.qsl.net/ke6myk/
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