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tips for sd22 engines


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Hey all I have recently purchased a 720 with an sd22 and got it to crank over but not even a hint at firing. I have a hanes manual but they don't go over any diesel engine info. And some things just seem confusing such as the throttle cable is connected to a plate in the intake and the injection pump is hooked to some goofy looking thing down on the engine, does the throttle run off vacuum or something goofy?

I had some good pressured fuel going to it and was trying to get it to bleed but my priming pump is stuck. The old girl has been sitting for a long time has normal rot like old brittle hoses and such and i will get good fuel in the tank and i have to find the right key too i got it to on but then was using a starter button so maybe that was stopping the fuel shutoff from opening? 

Does anyone have much insight on these engines and any tips to get them going without hopefully buying too many expensive parts.

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Get the correct year 720 factory service manual (FSM) if at all possible. The SD (diesel) was used both of these years. The FSM will cover in depth anything you want to know about the SD22. Haynes are rubbish. They stuff 7 years into a 1/2" book. My '84 FSM is 1.5" thick. E-Bay, Ali baba? 


Your build date should be on the driver's door jam. The changeover to the next model year begins with June build dates of the previous summer. So a build date of August '81 would be an '82 model year. Or post the 17 digit VIN, I think Nissan had them starting in '81. If an '81 the 10th digit is a C. '82 is D



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That “thing” on the side of the engine you mentioned is the injection pump controller. It rotates to 3 different positions. “STOP”, “START”, and “RUN”. If you have an extra person have them crank the engine and see if it moves during cranking. Sometimes you can hear the mechanical motion from inside the cab if you listen closely. If the controller pump isn’t moving to the “START” position while cranking, try disconnecting the transmission connector located near the glow plug connector and see if it cycles itself. This will tell you if you controller is working. There’s a few other things you could try but if you search the forum or type in google “SD22 DPC module” then google will direct you to this website with the specific forum where others go into greater detail about the operating system and doing a field test on it. Also if you PM me I can pass my info to you and see if I can help at all to show you how I operate mine. A lot of people have gone to a cable and knob system, which I haven’t done yet, but may need to if the problem stays intermittent. It’s not fun popping the hood to get the truck started half the time 😅

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