Re: [MV] Cummins run away

From: MV (MV@dc9.tzo.com)
Date: Sat Jun 11 2005 - 10:47:18 PDT


Joe,

No matter what way you cut this problem - the base result is that you
have a engine governor problem. I'm not familiar with that engine, but
I beleive that is an older design with an all mechanical governor/fuel
injection pump.

The governor is not responding to the changing rpms of the engine by
itself - hence you have to run to the throttle and basically do the
governors job by manually adjusting it. Somemore research on the
injection system on that truck will identify how it is governed. I bet
you have some problem resulting from corrosion - water in the fuel -
that has resulted in a sticking regulating piston internal to the
governor/pump. I doubt that this problem is related to current fuel
lubricity issues. I believe those issues result in decreased pump and
injector life - not sticking governor - irratic operation issues.

Something is sticking in the governor/fuel injection pump system.

Good Luck,

Dave

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

noel shelley wrote:
> Hi Joe ,
> Has your engine got an conventional injection pump ?ie in-line
> or rotary ? Is it air governed , hydraulic or mechanical ?
> OR is it Cummins P/T {pressure/time injection system}
> This last method involves cam operated pump/injectors in the head , fed from
> a main pump !
> Hydraulic governing involves the fuel pressure and somewhat perversely ,if
> the fuel filters are partially block the drop in pressure is seen as a
> command for more fuel and off she goes !
> Mechanical governing is a simple centrifugal arrangement of rotating weights
> and springs , BUT if there is corrosion due to water in the fuel or the
> fuels lubricity is too low things can
> stick , sometimes, open othertimes shut !
> Once started a diesel engine can ONLY be stopped by cutting off the fuel ,
> stopping the combustion air , or by over powering the rotating force ! THERE
> IS NO IGNITION SYSTEM !
> BUT first you need to know if she`s running away on diesel fuel or some
> other ? Engine or diesel oil finding it`s way into the combustion chamber
> in an uncontrolled manner will result in a runaway and potentially
> catastrophic failure of the engine , read explosion , in spectacular form !
> The normally accepted method is to stop the incoming air BY ANY method ,
> lump of wood , sheet of steel , BUT NEVER ANY PART OF YOUR BODY { a runaway
> beats any vacuum cleaner }
> If water finds its way into rotary pumps ,the first sign of trouble in road
> vehicles is that the engine will often stop when called upon to tickover !
> It will restart fine ! This is a sign that the fuel valve in the pump is
> sticking , and will soon stick for good ,leaving you stranded !
> There is nothing you can do except have the pump rebuilt at a considerable
> cost ! ie $500 . Some fuel filters are as little as $3 and draining the
> filter bowl is easy ! A SOUND INVESTMENT !
>
> Hope the above is of interest to some , Noel
>
>
>
>
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