1994 6.5 turbo diesel no power black smoke

[jrgooch]

I have a 1994 6.5 turbo diesel it started loosing power and was pouring out black smoke from the exhaust it would idle great but when I gave it throttle it would just smoke really bad. About a week pryor to this I put on a new lift pump I think the old one was still good I just thought it would be good to change it .i took it to a local mechanic he has had it 3 weeks. There is no error in the computer he says the waste gate is working properly he just had the injector pump rebuilt. He drained the fuel tank and put in new fuel and it runs worse he doesent know what to do next and I don

[16gaSxS]

Black Smoke is unburned fuel. So either your getting too much fuel or not enough air (boost). RJ had a problem with his turbo the wastedgate controller itsell was okay but the shaft the wastegate was mounted on had a notch it wore and would not operate up to snuff. I would get the truck back if this guy hasn't figured out what's going on with it by now he may never. Many of us have found it's better to DIY and get help from here or find a GM 6.5 specialist. Yeah they are Diesels but they have some quirks that unless a mechanic knows the systems will have problems solving. Did the guy time the IP properly?

If the turbo spins freely odds are it's something with the wastegate. Could be broken or leaking vacuum line. Could be vacuum pump, could be soleniod or the wastegate controller.

[JDave]

My company had a 3500 6.5TD that the airfilter was neglected and when you pushed it the pleats would fold over and stifle the flow. Make sure your filter is good shape.

[rdurh]

I had a similar problem, black smoke and all. At idle the wastgate solenoid checked out OK. However, under load it wasn't working, or not very well. Replaced the wastegate solenoid with one from RockAuto and no problems. Cost was around $30/$40, versus two or three times that from the dealer.

[Rodney Walker]

I was having same problem as you. My cat was plugged. Cut it out mileage almost doubled.


1994 chevy 1500 new cooler, pmd ,marine injectors, new injection pump, k/n stock filter &3.5" exhaust today.

[kevin77]

If you replace the Wastegate selenoid, make sure that the supply for the vacuum pump goes to the restrictor in the selenoid see https://www.thedieselpageforums.com/tdpforum/showthread.php?p=22348.

Been there done that.

Kevin

[markelectric]

Oncce upon a time I had a 94 doing just that. The dealership could find no wrong but when I removed the turbo I found the wastegate swinging on the shaft. About a year later the other 94 did the same symptoms and I found the actual "gate" was gone. Both were perfect on the outside by looks but very wrong on the inside.


This is where a boost gage is your friend....................

[Bnave95]

This is where a boost gage is your friend....................
So true,when it comes to boost problem this is the only way of knowing if there is boost or not.

[jrgooch]

I was having same problem as you. My cat was plugged. Cut it out mileage almost doubled.


1994 chevy 1500 new cooler, pmd ,marine injectors, new injection pump, k/n stock filter &3.5" exhaust today.

thanks you were right it was a plugged catalic converter 3 weeks in the shop and almost $2000 later for a problem i could have fixed for $30.00 i learned my lesson i will go thrue here and try everything possible before i go to a mechanic thanks again jim

[Mark Rinker]

$2000 for what?

I would go back to the shop and negotiate a reduction in the bill if they couldn't properly diagnose a plugged cat.

You should not be paying for their incompetance when it comes to diesel repair.

[ees]

I had the black smoke problem about a year ago. It was great for getting rid of tail-gaters, fogging for insects, etc. Not so good for power however.

Turns out it was my s-belt tensioner. The vacuum pump does not have much of a belt wrap and it was not always spinning. I solved it with a new tensioner, ditching the vacuum pump and going with the boost master. Now everything works great!