Engine Help

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

Moderators: plenzen, Nissan_Ranger

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dieseljunky
Posts: 21
Joined: 16 years ago

Engine Help

#1

Post by dieseljunky »

Hello. I am running into problems on getting my SD22 running correctly and have a few questions. I recently replaced the pneumatic governor diaphragm and a new fuel filter. The engine fires right up but pumps out black smoke mixed with white smoke. I have not replaced all the vacuum lines yet, but have inspected them and do not see any visual cracks.

I have a 3/8" fuel line sucking fuel out of my temporary tank. Will that big of a fuel line cause the injection pump to suck to much fuel causing the engine to produce black smoke?

I am confused why there is so much black smoke. When I pulled the engine out of the first pickup it smoked a little white smoke at start up and then cleared out. Now when I start the engine I can not get the smoke to clear out.

What would happen if the alternator is not producing vacuum?

Do any of you guys have any advice or what to try next? Any help would be greatly appreciated.

Thanks.
plenzen
Posts: 893
Joined: 18 years ago
Location: Cochrane Alberta Canada

#2

Post by plenzen »

Size of fuel line is not an issue. It (the engine) is simply getting too much fuel for some reason. Vacuum lines have nothing to do with it. The vacuum pump is there basically to run your brake booster, and operate the butterfly in the intake. A certain amount of white smoke at start up is pretty normal for the older diesels and once there is some temp. in the cylinders it clears out. I would suspect that when you replaced the old governor that something in the fuel rack changed and that it will have to be re-adjusted. There are a couple of "smoke" screws on the pump and they will have to be re-adjusted. Search this forum for links to adjusting the smoke screws. I know I have read on them somewhere but cant recall where. If I find them befor you do then I will edit and put the link for them.
Edit:
I went in search and there may be something in this thread : http://nissandiesel.dyndns.org/viewtopi ... t&start=15. It's quite long ( 5 pages) and there are some interesting points in it. There may be a link within that thread to take you elsewhere.
HTH
Paul
Last edited by plenzen 14 years ago, edited 1 time in total.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
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dieseljunky
Posts: 21
Joined: 16 years ago

#3

Post by dieseljunky »

Thanks Paul,

It smoked just as bad before I replaced the governor diaphragm. Maybe I jiggled something when I was swapping the engine. I will read on the smoke set screw and give that a try next time I am home. Hopefully, I can figure this out. Don't want to look like I am on fire every time I start the ol girl up! Thanks for your help.
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