Blck smoke (1 Viewer)

[mallred]

I have my 81 BJ42 back on the road, I am getting quite a bit of black smoke whle excellerating and on inclines, the injectors are rebuilt, new rings and valve job were done this winter and this is the first it has been running, I would say it is about the same as before all the work.

From what I find in the FSM is that they talk about retarding the pump and I have no problem doing this but I am wondering if the PO did ramp up the fuel. ( he did state that he wasn't getting the fuel mileage that he tought he should since he had the truck, 8 years)


I guess what I am asking is how do I find the balance between the fuel setting and pump timing. Or how to set the fuel properly.Rignt now the pump is on the lines.

I am thinking backing off the fuel should be my first step.

81 3B NA

Myrle

 

[M John Galt]

I have a 13B-T and I'm also getting more black smoke on acceleration than I would like, especially in traffic. What does one adjust to reduce the amount of fuel at low RPMs.

 

[roscoFJ73]

Im not sure which buttons you press on a B motor but my diesel shop puts it on a dyno and when they have max HP with no smoke ,its done.
They are dialling it in under load and reckon its the best way

Fuel injetion shops also talk about matching the injectors with each other and the pump but I dont fully understand it.

 

[Tapage]

black smoke unburng diesel .. reazon . ?

Air in my books are the first reazon to black smoke. Air filter or more diesel than the engine can burn.

No matther what if you are towing a 2000 lbs trailer in 3rd gear to start run, you get black smoke.

 

[s79bj40]

diesel injection shops may want to match injectors with the pump if the pump isnt completely consistent in pressure between each of the lines. If one is a bit down, they can back off the opening pressure in the injector slightly to make sure its making the proper pattern. This however is getting a bit serious for your average occa.

 

[Otterav]

Hello,
My diesel background comes from my military truck. I believe the theory is the same, with execution the difference. My truck has a few adjustments, the first is a ramp, which determines how quickly the pump increases the fuel vs rpm, and the second is total fuel flow for a given throttle setting. Adjusting the ramp will change the amount of fuel added when accelerating(black smoke), where the total flow adjustment determines the max fuel allowed. The total flow adjustment must be approached carefully, max exhaust temperature must not be exceeded, each engine has its own number, but 1100F is a starting number. Matching the settings is a task best left to a shop with a dyno and the necessary equipment to achieve optimal performance. Without the necessary instrumentation it is hit and miss at best, with a hit meaning acceptable running engine and a miss meaning holes in the pistons.
Otter
P.S. I forgot, you were talking about timing the pump, pump timing is the equivelant of ignition timing, it is a mechanical tie between the crankshaft and pump. I had to change the timing on my 2 1/2t normally aspirated engine when I added a turbocharger, the timing went from 25deg, to 20degBTDC. The timing is easy to check, unlike ignition timing, usually it is a mechanical match, place the #1 on TDC and check the pump through an access window, check the FSM.

1968 M109A3 with custom 2 1/2 ton trailer

 

[M John Galt]

Nice looking truck, what sort of MPG does it get? No criticism intended, just curious.

 

[Tapage]

Dude .. nice nice truck ! it rocks !

You can own a military truck and drive ( if is street legal ) on US : ? ( keeping the military paint )