RWD SD25 in Canadian winter?

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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Re: RWD SD25 in Canadian winter?


Post by plenzen »

You see the vacuum pot on the side of the intake where the air cleaner sits with the single vacuum line. Its just above the red air heater power connector insulator. There is an electric switch that's mounted to the fuel pump. Once that switch closes it activates an electric valve on the firewall that allows vacuum to open the throttle plate. You can set at what RPM that butterfly opens fully and you can also set how much its open at idle with no vacuum. Its either open all the way or at its static setting.
There is a setting in the FSM for how many thou. of space and at what RPM to open fully. It gets its vacuum supply from the vacuum pump at the rear of the alternator.

I think there is a picture of my fuel pump on here someplace. I will try and find it.



Could not find the picture but did find find this explaining it from a few years ago. ... ump#p16237
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1987 D21-J SD25 KC
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Re: RWD SD25 in Canadian winter?


Post by waynosworld »

Well that is interesting, a cold start setup for Canadian SD25 diesel truck engines from the factory, I would have thought it would just be a tube sticking up to connect the air filter housing to.
I always wondered what that other vacuum port on the alternator vacuum fitting was for.
I know the voices are not real,
but they have some really good ideas.
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