89 loss of power then suddenly lots of power

rs359

rs359

New member
I have a friend with an 89 1 ton he has been asking how to make more power with the truck because his truck seems to have lost power . I advised him to him to try to find the cause of the lost power before trying to make more.
Today he came in and said the truck was pulling a heavy trailer, and it started loping a little then, when he stepped down on the throttle he heard tires squalling and saw a good deal of black smoke. He thought something locked up one of the trailer tires and backed up only to see Dually burnout marks on the pavement. The truck has lots of power now and we are concerned that something bad could be round the corner.
I know the truck has about 360,000 miles on it and has a different injection pump off of a Grader but it was changed a few years ago without any problems.
The loss of power has been going on for about 6 months now until Today. Sorry so long but this ones got me stumped.:bang Rich
 
Perhaps you had some crud restricting your pickup assy. in your tank or filter and it finally broke loose. Perhaps your fuel pin was bound up so you weren't getting proper fueling and now you are. That's all I can think of right now but they are all very likely.

I would pull out your fuel pin and take a gander at the "witness marks" to see how much travel you have been getting and then put a little grease on the profile face.
 
"Fuel pin bound up"???

It could be so many different things, it's probably some "d'oh" thing that you'd have to look around to notice.

Throttle assembly working? Air filter clean? Fuel filter clean? Fuel pressure okay? Could be some sort of automatic transmission problem. Could be something sticky in the AFC.

Actually, if the symptoms really are as severe as going from underpowered to burnouts, it probably is varnish build up in the pump. I have heard of some accumulating so that fuel sleeves can get sticky and not slide on the rotor, or the fulcrum lever stops getting full travel, and that could explain very severe symptoms that would not be easily noticed.

Pull the top off the pump like you were installing a governor spring, and see what it looks like. See if you can manually move the fulcrum lever and control sleeve.
 
Unfortunately the truck doesn't have gages . I did look into turning up the pump and it looks real different. I think it did not have the Diaphram part on it but it has been a while since I saw it . That led me to think that the pump was designed for a non turbo motor .
I can see how it could have a buildup of varnish that could have moved into the wrong place slowed things down then cleaned up. I will check with him in a couple of days to see if things have changed any. Thanks Rich
 
They're like the P-pumps in that there is just about a different governor for every application, and they all have their own quirks. The AFC diaphragm was an emissions control device, I don't know if anything other than the automotive application used it.
 
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