Carburetor/engine problems

[CountryMan85]

I have a 1985 or 1986 Nissan 720 (title says '86, signs on truck show '85). But ever since I got the truck, it was missing the ECM under the seat. The truck has always ran rough and diesels after every time I shut it off. Idle is never constant, sometimes high, sometimes normal, sometimes in the middle, never the same. Could part of my problem be that I'm missing the module under the seat?

[foxfan1992]

My truck also diesels after I shut it off (not every time, just occasionally since I turned the idle down a notch). By 'diesel' I mean it shudders and backfires after turning the ignition off. I've been told it could be due to hot carbon in the cylinders (like clinker in a coal fire) it gets red hot and as such the engine diesels. Also known as 'pre-ignition'

Probably not the best answer you can hope for, but I'd check those cylinders and spark plugs just to see if that improves your problem.

[PEZi]

There is a solenoid on the stock carb that prevents this.... if it is gone or missing... or dead... it would explain all of this. Fix the carb... fix the problem, in my opinion.

[Glenn Schoettlin]

I have a 1985 or 1986 Nissan 720 (title says '86, signs on truck show '85). But ever since I got the truck, it was missing the ECM under the seat. The truck has always ran rough and diesels after every time I shut it off. Idle is never constant, sometimes high, sometimes normal, sometimes in the middle, never the same. Could part of my problem be that I'm missing the module under the seat?

I have the same truck and that ECM is important to keeping the truck running right. It contols the engine though a feed back system. Do you know if your 85/86 720 still has the original Hitachi carburetor on it? Some guys take the old carburetor off the truck and put on a Webber. Do you know the history of your truck? who was the original owner and any owners in-between them and you?

[xsdg]

As for the age, the correct month and year of manufacture should be listed in the driver-side door jamb. Of course, if there were an engine swap at some point, then that might not accurately represent the age of your motor.

Yeah, if the ECM is gone, that means that the anti-dieseling solenoid is either disabled or broken — the no-power state of the anti-dieseling solenoid is to cut fuel, so if the truck fires at all without the ECM, then that's not working properly.

That said, it should be possible to tune the carb to run at least okay without the ECM in place — the truck will run in open-loop mode during vehicle warmup anyway, and if the ECM is missing, the A/F solenoid shouldn't be getting any power.

One thing to note, though, is that the choke may never open if the choke heater circuit isn't getting power (which I would expect, given the missing ECM). In that case, the truck may be running lean once warmed up because it's choked. Open the air cleaner with the truck running and check the passenger-side barrel of the carb. The choke valve is at the top of that barrel, and if it's not in the completely-vertical orientation after a couple minutes of warmup, then that's a big problem, and will cause the carb to run _way_ lean in open-loop mode.

[aiallonardo]

Thanks for letting me in here .....

1983 Nissan XLT (that's what the pink slip says !!) w/ z-24 engine.

It has 8 plug wires.

VIN JN6FD06S5DW004830

Can anyone lead me to the stock Carburetor ????


Thanks again