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I have a 1992 RD690s quad axle with the E7300 and 7 speed trans. When I got the truck it was rolling blk smoke when going down the road, but it clear after you change all the gears. So I was told to change the injectors, had them rebuild & the rack was ran. The truck stills smokes but not as bad. So today everytime I got loaded the truck would smoke like a tire on fire, and her power was way down. Get the load off her back and power was back. I don't know what to do. This is my first truck. Can somebody help me out.

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And after you make sure itr dont have a boost leak on the coller plumbing make sure that the hose from the intake to the air compressore is not leaking boost. The i would pull the exhaust and intake off of the turbo and look at both ends. Look at the exhaust wheel and make sure there is no tips bent of missing on the exhuast wheel.

glenn akers

Went over everything and found no leaks. Buddy of mine hooked up a boost gage and the truck is showing it's make 11-12psi unloaded. Is this the nomal boost range? He thinks the timing is off on the truck. The truck has new fuel & air filters also.

No, that's way low.18-23 psi is normal boost.21 is about avg. turned up pump is 25 psi...Check the turbo like said above. I had a housing melt away allowing exhaust to bypass the blades and thus no boost over 14 psi could be made...

No, that's way low.18-23 psi is normal boost.21 is about avg. turned up pump is 25 psi...Check the turbo like said above. I had a housing melt away allowing exhaust to bypass the blades and thus no boost over 14 psi could be made...

Yup

check for leaks or the turbo your way down on boost!You need to preasure up the intake side of the engine with at least 20 psi to fined leaks properly how are you checking it?

Well guys, the guy working on my truck thinks my problem is in the injector pump. That's why the truck is over fueling when it gets aload on it. When you back off the gas some it some of the smoke clears up and you have to the truck build speed like that. He was saying when he was cracking on the lines #2 goes to flutting abit. I'm new to this, but I'm trying to learn as much as I can. I just had the injectors done, and ran the rack. He checked all the lines, hose, and the turbo. In the morning I'm taking it to a guy that does injector pumps, I'm about to go trucks with this truck!!!

Well guys, the guy working on my truck thinks my problem is in the injector pump. That's why the truck is over fueling when it gets aload on it. When you back off the gas some it some of the smoke clears up and you have to the truck build speed like that. He was saying when he was cracking on the lines #2 goes to flutting abit. I'm new to this, but I'm trying to learn as much as I can. I just had the injectors done, and ran the rack. He checked all the lines, hose, and the turbo. In the morning I'm taking it to a guy that does injector pumps, I'm about to go trucks with this truck!!!

Hope Hes Right! :pat:

  • 2 weeks later...

Yeap he was right the problem was in the pump. Replaced a part on the back of the pump and the smoke cleared up. Got a half a day work out of the truck. Guess what? I got me a reman pump from Mack and it's going on Monday. So if the Lord is willing I can run problem free for a while.

Yeap he was right the problem was in the pump. Replaced a part on the back of the pump and the smoke cleared up. Got a half a day work out of the truck. Guess what? I got me a reman pump from Mack and it's going on Monday. So if the Lord is willing I can run problem free for a while.

Air fuel control diaphragm?

post-6084-0-59389800-1307793727_thumb.jp

"Mebbe I'm too ugly and stupid to give up!"

I have a 1992 RD690s quad axle with the E7300 and 7 speed trans. When I got the truck it was rolling blk smoke when going down the road, but it clear after you change all the gears. So I was told to change the injectors, had them rebuild & the rack was ran. The truck stills smokes but not as bad. So today everytime I got loaded the truck would smoke like a tire on fire, and her power was way down. Get the load off her back and power was back. I don't know what to do. This is my first truck. Can somebody help me out.

My FIRST suggestion is to take the air cleaners out and try it. If that clears up the problem than you know what caused it. When I was in the trucking business I had more than one shop try to sell me injectors, and turbochargers in similar problems, and sometimes it was an injector or turbo, but pretty rarely, because I watched the exhaust stacks and other symptomatic areas when the trucks were on my yard. An injector should smoke all the time,,, just like a turbocharger would. If the air cleaners don't fix the problem, check the boost pressure line going from the intake manifold to the pump. When the boost pressure is low, it will sometimes allow more fuel into the injectors. Likewise when the boost (manifold pressure) pressure is high, it will automatically decrease the amount of fuel flow through the pump.

Hope this helps.

Dan.

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