SD 22 quit abruptly

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.

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Ldog
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SD 22 quit abruptly

#1

Post by Ldog » 4 months ago

I believe I read if the engine is running, then there is no air in the fuel system as it is "self bleeding" ?

Anyway, the engine quit abruptly. But I was able to start again. I would greatly appreciate any thoughts on this. It has a push-pull solonoid on the stop lever, but it seems to be working.

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asavage
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Re: SD 22 quit abruptly

#2

Post by asavage » 4 months ago

In normal conditions, a diesel engine shutting down is a fuel problem, as they always have air (even diesels with throttle valves always have some air, so they'll at least idle) and compression problems don't cause a running diesel to stop running.

So, let's assume your engine has a fuel delivery problem.

There are three broad categories of diesel fuel delivery problems:
  • Fuel restriction to IP
  • Air getting into fuel
  • Catastrophic failure of the IP
IPs wear out, but the Nissan IPs seldom fail catastrophically. The most common problems are pulling air into the feed side of the IP, and restrictions of fuel to the IP.

For air leaks: the 720's fuel filter housing has a primer diaphragm that can fail and leak air into the filter housing. Hoses can develop cracks after decades. Fuel will not necessarily leak out to show you where they are.

For fuel restrictions: bad, plugged, or incorrect filter(s). Paper towel in the fuel tank (see the third tale here). Plugged screen in the tank -- yes, the 720's tank has a screen that you can't easily clean. Running diesel in a galvanized gasoline fuel tank (diesel will "eat" the zinc and move it to the filters and IP). On the SD22 with Inline IP: fuel lift pump failure (rare, but it does happen).

More reading: Wrong 720 diesel primary filter.

Diagnosing fuel delivery problems always involves tee-ing a vacuum/pressure gauge into the fuel line, preferably with a section of clear tubing so you can see air bubbles if present. See this post for details.

You don't mention where your SD22 is installed (720 PU, ag water pump, marine), so I can't venture more guesses, but those are the first things that come to mind.

[later edit}

See also this guy's post, after he installed a vacuum gauge to the IP's feed line.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

Ldog
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Joined: 4 months ago

Re: SD 22 quit abruptly

#3

Post by Ldog » 4 months ago

Thanks for all the great ideas. It is a marine installation. After the abrupt cutoff I was able to start it again. I replaced the solonoid. Maybe that was the issue. I'l check on the other items as well.

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asavage
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Location: Duvall, Wash.
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Re: SD 22 quit abruptly

#4

Post by asavage » 3 months ago

Hmmm. Maybe I typed an article, when I should have said, "check the fuel cut solenoid", but that's life!
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

Ldog
Posts: 7
Joined: 4 months ago

Re: SD 22 quit abruptly

#5

Post by Ldog » 3 months ago

I replaced it. However when I put it in forward (boat installation) it will not rev up beyond idle.

truewind
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Joined: 1 day ago

Re: SD 22 quit abruptly

#6

Post by truewind » 1 day ago

Did you figure out what was wrong?

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