samahi72

98 67k actual. Automatic Tranny
I just bought this truck, my first cummins, I am so proud. Anyway acceleration is poor, and it bellows out a tremendous amount of black smoke. I also notice that it will buck and jerk unless I have the o/d button pushed in. I got a gut feeling these two issues are the symptoms of a common problem but what??? Also this truck came from California. I am a mile high in Colorado Springs. Do I need to do anything to adjust it to the higher elevation?

Chass

Sounds like a truck I saw go through the auction here. Seems that the turbo was going out. It was dumping fuel in but no air so it bellowed black smoke and had no power.

I think you can buy a boost guage for around $30 and your truck is pre plummed on the intake for it.

Might be a good starting point.

Chass
ct

samahi72

Could a turbo go out with only 67K miles? What readings should I expect to see on the guage?

Thanks

infidel

You should see under 20 psi if stock.
Could be as simple as intake hose blown off.

dodgethis91cmns

your injector pump might be to high. idk if they are adjustable but i have a 91 cummins and if i stomp on it on take off it will bellow out smoke but none after that unless im doing a brunout. black smoke itsnt bad when u take off but for long periods of time it is a symptom that your running really rich.

Rare1

Black smoke is unburned fuel. What does your power feel like? Measure boost, as was mentioned. Check for loose/busted pressurized air hoses both before and after charge air cooler. Check fuel plate type and position, AFC screw position. Report back.

samahi72

Man what a great site. Thanks for all the suggestions, I can do some of them but I am new to diesels. So some of the recommendations are presently beyond my mechanical aptitude. I am willing to do on the job training and I don't shy away from repairs so this will be a learning experience for me. See my next thread. Thanks

Rare1

Also, tell us if you have a 12 valve or a 24 valve engine, the changeover to 24 valve was 1998.5.
The two symptoms you listed in your inital post are not necessarily related. Not unusual to have multiple unrelated problems, making diagnosis difficult. As you get familiar with the machine, you will discover what has been added/deleted. Hopefully it is unmolested and only needs adjustment and a maintenance catch-up.

samahi72

it is a 12 valve. I don't know if I should have mentioned this earlier but who knows. It does have an exhaust brake hooked up but I didn't mention it because I didn't think it cause either symptom.

cumminsdriver635

My guess is that you have an intercooler boot blown off. A boost gauge would tell you if you did or not, but, just pop the hood first, and make sure every clamp going from the turbo to the intercooler, and then from the intercooler to intake horn is tight with no holes. Good luck

Eric

Racer9

I didn't see anyone mention checking the air filter. Likely it's an intercooler boot, fairly common. Possibly an egr problem, on a California truck.

samahi72

I am going to check all of the above this weekend. I will report back.
Much appreciation.