I got a 1980 dm with a 300 in it. Its lost most of its power. Were doin the basics filters and checking lines. How much fuel pressure should it get from the mechanical pump? How does the puff limiter work, like to ajust it or check to see if its not working? Its a dog, it will lug down but no smoke egts climb faster than before, didnt find any air leaks. Any input welcom.
You should have have about 30 psi pressure. Do you have a transfer pump on the injection pump or is it driven off the Tach. drive. The tach drive units were famous for sucking air. As for the puff limiter it is reversing relay, as turbo pressure increased the pressure on the rack piston decreased and you would get more fuel. these used to screw up and we just pulled the line off the rack piston ad put a screw in it to block it. If the truck is still on the road you may get pulled over for excessive smoke when shifting.
I would look at the reversing in addition to the puffer valve. reversing relay is on the intake manifold.
Ill pull the line off tomorro and see what difference it makes. Origanally it was of and we put a new one on and it worked good for 6 months and then it started lossing power. Its a tach drive transfer pump, but it runs silky smooth just no power, we had a fitting crack last year and it would run ruff, hard starts stall frequently. Now it purs like a kitten just know go.
Wheres the puffer valve in relation to the reversing relay. The one i see is on the intake manny with an air line from the dash going to it and a line that goes to the front of the injection pump. I took the line off the front of the pump, it has some thick greyish oil in it, not a lot but enough to make one drip. With the line off it made, very little difference. A tad bit of smoke and slightly better bottom end, still dead on top end. Fuel pressure is good, and so is volume. The transfer pump is run off the side of the injection pump, no leaks or air suction. To me it seems like the rack isnt goin fully open in the injection pump, is there a way you can measure rack travel on the pump while its in the truck? (like a p7100 on a 5.9 cummins)
Next thing is to check is that the throttle linkage is going into full fuel Have someone in the cab (engine off) while you are watching the linkage on the side of the pump the lever on the pump has on over center spring. the shaft from the pump will stop but the lever should go a little further. when you let up off the throttle the lever will go back to the center position and back to idle. The white stuff coming out of the air line is compressor oil and water try draining all your air tanks. There is no way that I know of checking the rack on the truck, you can give it more fuel but don't try that now or it can get screwed up worse, fix the underlying problem first.
Im pretty shure its got full travel, but ill double check again. Last year if you just blipped the throttle it would throw a cloud of smoke, now its just a haze even whith a heavy blip. It seems like its not getting proper rack travel.
Just a thought Ive had a lack of power issue before ,it idled and ran fine turned out to be fuel filters.
Filters have been changed no dice there.
I'm thinking the puffer valve is stuck from the grey goop. Isn't spring loaded? Probably full of goop and won't move. I hope it's that simple. Sure sounds like it.