Over the past few years my 92 W250 has occasionally – once every few months or a year – simply refused to start as though it was fuel-starved (when it usually fires before one full rotation – typical Old Cummins). Whenever that happened, I usually replaced the fuel filter, primed with the lift pump, bled injectors, and got it going in an hour or so.

This time, however, while replacing the fuel filter, I removed, inspected, cleaned and reinstalled the "fuel heater" that is between the filter and the mounting surface. The truck started promptly – but leaked a lot of fuel near (and apparently above) the filter.

Since tightening had no effect, I questioned the seal of the O Ring at the top of the "fuel heater" because it seemed to be overly flat and depressed. Finding one of the appropriate size took a couple stops in town – but that stopped the leak and the truck started instantly.

I suspect (but cannot say for sure yet) that the O Ring was the source of that intermittent problem for all these years. Though I can't promise it will solve similar problems for others – let's hope that it will be of some use to someone.

 

Where did you get to the O-ring? Did have a part number or some other way to identify it? I ask because I need to replace mine. Thanks.

 

believe it or not I used the oring off of a napa 1036 oil filter. Driven it for about a week with no leaks... its much much thicker but it is the right diameter and I havent had any ill effects as of yet...

 

I hope in your case that the heater-seal does cure the no-start problem, but I am not betting on it.

The wife's truck like to have run me nuts, catching her out and refusing to start.

Everything would be fine for weeks and then it would refuse to start.

I did all of the usual fixes, such as eliminating the spade connector at the solenoid and using a ring-terminal instead.

I finally replaced the rat's nest of fuse-links with completely new wire and breakers, plus ran new wire all the way to the fuel-stop solenoid on the injector-pump and after about two years it has never failed to start since.

 

UPDATE

Bear was right to doubt the "fix". The truck failed to start one time since -- but did start on second attempt. I will rework the electrical next -- anyone got a schematic or some directions / advice (sparks ain't my long suit)?

The O Ring we found came from a heavy equipment supplier and was a bit thicker but the right diameter. It may not have been the problem, but it stopped the leak (and cost half a buck).

 

It figures, one of the few times I'm right about something, it is bad news...



As for the leaking heater-seal, I have had the heater-seal on more than one Cummins to absolutely pour a leak and the engine never skip a beat.

The son's injector-pump was throwing a stream of diesel broad as a handsaw blade from the main head o-ring in the injector-pump and never failed to fire as soon as the key was turned.

In my own experiences, I believe any fuel/air leaks must be North of the lift-pump before being manifested as an air intrusion.

 

3834185-S is the gasket part# its only available at a cummins parts supplier, as far as starting problem id bet its the lift pump (40$ at genos) online, i just had to replace mine I was having the same symptoms