A QUESTION ABOUT HOW THE ENGINE BEHAVES

[jb]

Hi to all

I am new to this forum but I hear this is "the place to be."


I have what may be a common problem, possibly not, I bought a 1990 w250 a year ago and turned the pump up two turns + a 4" exhaust about four months ago. I tow fairly heavy loads (10-14k) and I'm pretty happy with what I've got.


I towed a 14k load a while back and noticed afterward that the truck really didn't seem as strong as before the trip, (no other symptoms)

I towed another time and noticed that after a few hours on the freeway the engine seems to loose the torque, I have to put my foot into in to keep the load going down the road AND if I pull over to check a load the engine idle is a noticeable lower.

I towed another load but it was only a small trailer, this time I began to notice that the truck runs fine going down the road but if I'm coming down a long grade the truck acts as if it's completely run out of fuel when I get back into the throttle, I have to hold the throttle for a few seconds then it snaps back to life.

I've been a mechanic for over 12 years so I naturally began to play with the problem, I noticed that if I just barely let off the throttle coming down a grade then get back into it there isn't a problem, BUT if I'm coming down a similar grade and take my foot out of it completely the problem happens every time.

Any ideas?????

[CumminsPride]

Welcome to the forum!


Sounds like fuel supply issue. Or Nearing IP failure.

[Ace]

Yeeeeep. Something between the fuel tank and injector tip not quite right.

[cummins king]

cold be a few things
1. change fuel filter
2. check fuel presure to make sure you getting enough
3. thransmission expesialy if its an auto

[jb]

I don't seem to have a lack of fuel, the truck still goes up the hills just fine. the truck only has the stumble when decellerating AND I take my foot out of it completely, if I take my foot out of it just a little then go up another hill there's no problem.



I'm just wondering if there is someone that has any tech. info on the pump, injectors ect. I really like theory& opp. info and manuals. If not I would be interested in working with some people to create some good resource materials for everyone.....anyone interested?????

I do a lot of Autocad and engineering work so I would need some people that have a solid working knowledge of how the injection system works+ what happens when you screw with it, also people that can get a hold of blueprints.

[dpuckett]

Good luck with the blue prints. There is a good explanation floating in cyberspace of how the VE pump works, and a few people have operations manuals in PDF. KTA knows more about them than most people I know.

If I were to give my 2 cents, I'd say it coud be supply- check pressure under load, or springs in the pump getting tired. It's a good idea to replace the springs about 225-250K as a preventive measure. They can only compress and relax so many times before something gives. Yours sounds like governor springs or weights not quite up to par.

Welcome to the forum.

Do you have a pyrometer and boost gauge yet?
Daniel

[jb]

Which springs are you refering to?

I have my gauges. The pyro went down a couple hundred on the top end (now 950-1050F) and the low end is down about a hundred(now 300-400F@idle) and (now 500-700F@cruise)

The boost is bouncing around at 25PSI, it was getting up to 30PSI.


Does anyone have a ve pump they would like to part with?