Need help timing sd25

[tdaaj]

There's an old timer not too far from me in need of some help or advice. He has a 720 that was originally an sd22 truck that he swapped an sd25 into. Says it runs but burns too dark. Thinks its a timing issue. He is located in grand mound WA. Would really appreciate anyone who would be willing to give this old guy a hand. Said he might be willing to trade another diesel engine for help getting his beloved 720 up to par and back on the road. Pm me for details.

[wayno]

Does the engine idle weird/high Ted?

First thing I would do is check the vacuum line between the throttle body(carb looking thing on the intake manifold) and the injection pump, it cannot have any cracks/leaks, if it does it will burn rich and idle weird, if that is good then he needs to check the diaphragm on the back of the injection pump, if it is cracked or dried out and not flexible anymore, it will also make the engine run rich.

If the engine has sat for a long time the diaphragm could have dried out if there was no longer any castor oil in the cavity on the injection pump side of the diaphragm, it is just the way it is, eventually stuff gets old when not in use or not serviced regularly.

Timing doesn't control the fuel mixture, vacuum does on these inline injection pumps, don't mess with the timing of it.

[tdaaj]

I know nothing about these engines. I guessing its probably idling wierd too . Basically he's just at his wits end trying to figure it out. Guy is almost in his 90's and I'm sure even though his memory is fairly sharp still hes over looking something. Says he hasn't found anyone who knows anything about the sd25. He knows the sd22 by heart. I don't know how much difference there is in them. And i might not be relaying the message completely right either. Basically just need a second pair of eyes who knows something about these. I'll let him know what you said though

[wayno]

I forgot to mention that if he has just converted over to the SD25 engine, and got them two lines going to the injection pump backwards that it could possibly cause the same issue, one of the lines is a vent line, while the other line controls the injection pump rack(fuel mixture), if the vent line was put on the throttle body instead of the snorkel, once the engine was started the injection pump would be floored, but it would not be able to rev a lot because the butterfly in the throttle body is closed, it cannot get air, so it would blow a lot of black smoke.

I cannot drive up there right now, all I can do is tell you what I think the issue could be, the SD22 and SD25 work exactly the same if they have the same inline injection pump, the vacuum lines going from the injection pump to the throttle body/air filter snorkel need to be in serviceable condition and connected to the correct places, otherwise it's not going to run properly.

He has more than one diesel engine there, correct, make sure the vacuum lines are good and routed properly, he can look at other diesel rigs to double check.