[airbus]

I just reciently replaced the mechanical injector pump on my 93 gmc 6.5l TD, just got the timing set right on the thing, starts cold, minimal smoke, goes through the cold advance cycle, heats up and comes down to the quietest idle, running really smooth. You go to drive the truck, run the engine up around 1,800 rpm it starts smoking out the tail pipe and acts like it is bogging, like a gas engine with a bad carb. Back off the throttle, and baby it for a minute or two, and after that you can wind the thing as high as you want, no smoke, and runs like a top. I have bypassed the OPS with a paperclip, and the lift pump runs. I have also noticed lately that it sometimes surges for a minute after the initial start, and levels out. I have a good gas cap, new IP, new fuel sending unit in the tank. The lines seem to be ok from the tank to the lift pump, and have no leaks to the IP. Is this a normal querk???????

Could it be excess gas when it comes off the cold advance cycle, and the system demand is different because the IP is not advanced any more?????

Anyone seen this???????????

 

[Turbine Doc]

Better not be excess gas then you have some real issues :

What color smoke white or black, if black I suspect turbo issue, white I suspect timing problem

 

[airbus]

It looks to be black. If it is the turbo, why would it only act up at this point in the engine run cycle, and is there anything I can do other then replace the turbo?

 

[Turbine Doc]

Probably not the turbo itself, but a WG vac control issue. go through the WG FAQ

 

[airbus]

Hi Doc,

The waste gate actuator is of the non vacuum type, and all of the information in the FAQ is of the vacuum type. I do not understand how the non vacuum actuator operates, onless it breaks under pressure of the wastegate pulling on it. Is this a true statement?

 

[airbus]

I just caught the gas comment (hahahaaa)!!!

 

[Turbine Doc]

Guess I should have looked to the signature for the mech vac control myself; just so common to shout out check vac /wg solenoid when I see black smoke complaint.

Concept still remains, maybe your spring WG is bad or WG flapper, so try for a test to wire shut the WG fully, to see if it clears up. Just be gentle on the acceleration as you will get full boost quickly. If that doesn't do it, then you may need to look to pull the turbo to look at the WG itself.

 

[airbus]

I just want to have it right in my head , you are saying to pull the actuator to its full stop, and wire it there?

 

[ghitch75]

he is saying wire it shut so it won't open....so you can't move it

 

[airbus]

Thanks, I had a moment............. Just wanted to make sure I understood the doc. Again thanks!!!

Tom