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I was wondering how to tell if my 82 Diesel is missing on one cyl? I have never heard one run before so I am not sure if its right or not. It just seems to idle a little rough and I think it should be getting better mileage.
I have tried to adjust the timing by moving the injector pump but in retrospect I believe I should have waited until I had the proper tool ?
Thanks

If you gradually increase the idle speed, does it smooth out? When you adjusted the timing, you may have reduced the idle speed. They do tend to idle roughly if too slow.

These are simple engines, but years without maintenance can mean you just might have multiple issues. Things that MIGHT cause rough idle and reduced fuel economy:

• Air leaks in the fuel lines (rough idle)
• Bad seals in Cold Start Device (fuel economy and performance, but should not affect idle)
• Worn injectors
• Clogged fuel and/or air filters
• Clogged screens in banjo bolts on injection pump (performance and idle, but probably not fuel economy)
• Incorrect timing from prior work done (as you mentioned)

That's all I can think of for now. I'd start with the cheaper items.

It's hard to tell someone if their engine isn't performing up to specs when you only have a description. And if you're not an original owner, you may not know what "normal" really should be. How's the highway performance? Will it cruise at 75 MPH? Is this a 2wd 5-speed?

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

Yes. You are right (as usual) I do not know what the "norm" is for this motor. All I do know at this point is that it is running a lot better once I replaced the alternator. I don't know why that would matter since a diesel motor does not need elec. to run ?
It seems to have plenty of power. My speedo is not working yet so I am not positive of my cruising speed but I have no problem staying up with the traffic flow and it seems to pull great uphill.
If my fuel gauge is correct it is not getting real good mileage though and like I said a rough idle. It does smooth out though.
How can I check the R.P.M. ? There is no tach sooooooooooo??

The fuel gauge is useless for checking mileage. Since your speedometer doesn't work, I'm guessing the odometer doesn't work. So you really can't check your mileage now.

If it idles rough, it's quite possible that the pump is sucking air in through a leak somewhere in the fuel line. It's pretty predictable, if your fuel lines are original, they're way overdue for replacement. Be sure to get line that's for diesel fuel. I don't recall the sizes, but the supply line is larger than the return line. There are hard lines from the firewall to the back of the cab, but there's a section of soft lines behind that, going to the tank. You should be able to clip a really short section off of each one at the firewall, and take those to your local auto parts supply (or someplace that has tractor parts) and have them find the closest match.

I wouldn't worry about the RPM since you don't have a tach. But it should be pretty smooth at idle.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

Describe the rough idle. Does it sound like a cylinder isn't firing? If not but you're noticing the engine shakes a lot (make that, a LOT) then maybe all is OK. The C223 normally shakes at idle.

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Tom
'81 Luv diesel 4X4 - daily driver

Tom, mine has always idled pretty smoothly, except when the idle speed is too low (cold starting). But I think your question is on target and I meant to ask--does the exhaust smell like raw diesel? If one cylinder is getting fuel but not lighting, you'll have some raw diesel vapor in the exhaust. On the other hand, if the injector just isn't popping off, you won't.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

But you're talking about an engine that ran normally with a hole in a piston. Your truck is enchanted!

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Tom
'81 Luv diesel 4X4 - daily driver

I believe that all is ok guys. I cracked each fuel line at the injector while running and found out what a real missing cyl.feels and sounds like I am almost 100% positive that I do not have a miss.
I am still going to replace fuel lines in the very near future as suggested though.

As far as my mileage goes , I guess I am going to wait until I get my speedo working. In the meantime I plan on topping it off tomorrow and then taking a long drive (going fishing ) and when I get back top it off again and see how much she burned on the trip. I know how many miles the trip will be so I should be ok.

I will report my findings tomorrow. Thanks for all the help.

By the way. This truck is a blast to drive. I cant believe they quit making them !!

Well it did always start rough (albeit quickly), most likely on the 3 good cylinders. It took a few seconds to get smooth.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com