TRUCK(6.5 TD) RED LINES

[mike conrad]

My truck was surging about 200 rpm when cold. This lasted for a week. While I was trying to cure it by changing filters etc.... things got worse. Now it wants to red line just as soon as it starts. Any suggestions about where to start to cure this unit?

95 chev 2500HD, 6.5 TD with an auto transmission. It has About 225,000 miles. The injector pump has a green tag. I have installed a FDS cooler on it.

[lineman]

Mike,I had the same problem on my 93 6.5.It's the fast idle solinoid ( for the a/c )on the injector pump.I just unhooked the electrical connector on the solinoid until I can replace it.It's on top of the injector pump.The truck just won't idle up on cold start or while the air is on, but at least it won,t redline on startup.I remember when it first did it,the truck idled about 1500rpm on startup and I tapped the acc.peddle to knock it down but it went to redline like yours.Hope this helps. Lineman

[john8662]

Mike,

Actually, what "lineman" said wont help you out. the 92-93 6.5TD's were mechanically injected and were setup just like a 6.2 from the injection point of view. The 92-93 6.5TD's had a fast-idle solenoid that when energized pushed out a plunger that pushed the throttle down just slightly to allow a fast-idle. It was a mechanical device. The 94+ 6.5TD's are all electronic, including the fast-idle control. The 6.5TD is "drive-by-wire" with no mechanical cable to pull the throttle back. So, its all done by computer commands and controls and a fancy petal that sences position by resitance. As for the fix? I have read a few instances of a runaway 6.5 like what your describing, and I think it points to a bad injection pump or massive amounts of air getting into the system throwing it off. I would check for tight conections at the filter housing and for diesel leaks.

Lineman,

To fix your fast-idle problem you need to try and adjust the solenoid. i had that problem on my 6.2 once. I don't know why it decided to get off setting up one morning it did. So what I did to fix it was take a rachet and unscrew (just back off) the adjuster nut on top of the solenoid. you can feel it click as far is it is going to go. I would play with that. I don't think they go bad necessarily unless they burn up and don't work at all. Hope this helps!

[ucdavis]

John8662 is right about the '95. All electronic & computer controlled, so the symptom is indicating excess fuel rate or (tough to do this; I think it requires the wastegate to stick shut?) excess air.
You can check codes easily:
http://www.thedieselpage.com/members/trblcode.htm
You will get no code from a failing FSD, which must be involved to binge up the fuel rate, but you may have others. Check & post.

[lineman]

Sorry Mike and John,I did't pay attention to the year the truck was.I hope I did't cause you any trouble.I'll try messing with my solinoid before I buy one.It started acting up after I replaced my injector pump.Thanks.....Lineman

[charliepeterson]

Mike:

Last winter I had a runaway engine in our shop which sounds like yours could be heading towards. It started ok but when I brought the RPM's slowly up to 1200 she would take off to 4000 with no additional pedal. This tuck would do it in neutral or in poor traction conditions (snow). On dry floor everything was fine. Governed speed is supposed to be 3500 RPM's.

No codes were set. The Injection Pump came off and the truck is still making money.

I would keep a close eye on what it's doing incase it gets worse.

[david]

Sorry to say it is the inj. pump.
My son's truck started running amok, then it just would not even idle!!!!
Sorry i know how it feels.
David :mad: