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I have just found this club and have an 81 diesel. It is very hard to start even when it is 100 degress in the shade. The glow plug light comes on and i keep letting it repeat itself untill it fires. ive had this ol truck 16 years and have only bought a starter. just replaced the fuel filter no help. is there any way to check the glow plugs with out taking them out? Im sure this has been asked before but i have had now luck finding the answer. thanks a lot. a real oldtimer

oldtimer

The easiest test I can think of to test the glow plugs would be to take a piece of wire about 2 feet long, touch one end to the positive post of the battery, and briefly touch the other end to one glow-plug end, or the strip that joins them. If there is any arcing, then at least one plug is still good. Don't hold it there for more than 3 seconds, though, or you'll burn it/them out.

If it won't start in 100F temp by itself, then there is something else wrong. Mine will start on it's own when it's about 75F out.
Valve clearance is the first thing that comes to mind to check. Lack of fuel is also another possibility...hole in the fuel line?

There are numerous possibilities as to why the truck is hard to start (compression-valves/rings, injection pump, injectors, fuel delivery, slow starter-battery/wiring, etc). Over all, these engines are very reliable and long-lived.

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Bona Fide diesel fanatic.
1994 Chev S10 Ext Cab Isuzu Diesel 5spd
Kubota B6100 HST diesel

And note that he said "briefly". The plugs are 5v plugs, but the system does actually supply 12v to them briefly. One bad plug will cause the system not to work properly. Replacement plugs are available, there's a list of compatible ones over at IsuzuPup.com.

Jack

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

thanks guys i will put a volt meter on it and guess i turn on the key and measure when the light come on. there is a a metal band furnishing the power to two plugs so i guess i could narrow it down to two. thanks again for the help. i forgot to mention i have 170,000 on the old girl. a real old timer

Hi, just a thought, you can turn your key on until the gp light goes out. Then go under the hood and carefully touch the portion of the glow plg bus bar that is shaped like a U this conducts the voltage, it should be warm to hot. If you are heating that up the next is to pull and check continuity on each plug from theaded end to heat tip. This should show cont. If you got glow heat, fuel and comp. it should start. Hope this helps. Clair

Sounds like all the bases have been covered. This sounds more like a fuel problem than glow plugs.
ONLY 170,000 miles? Hardly broken in good.

FWIW, the engine in my 1991 Sonoma has about 350,000 miles on it (560,000 kms)...likes to leak oil and has blowby for sure, but starts up about as fast as you can flick the key when warm. When cold (below freezing ) it needs help, but almost never has it NOT started for me. Plugged in for an hour every morning in the winter and it goes for sure.

Had it for a 500 mile trip last year, and most of the time it was at 3200rpm (around 8 hrs). Didn't bother it one bit, and it seemed to run better after the trip.

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Bona Fide diesel fanatic.
1994 Chev S10 Ext Cab Isuzu Diesel 5spd
Kubota B6100 HST diesel

Thanks again guys, and especially Clair for giveing me something i can try. folks i mis- informed you about the the milage on the truck i ment it was on me. i am a real oldtimer. never knew any vehicle could last that long with out 90 perceant replacement. My mail lady said she had 360000 on her ford pu. then she began to tell me what all she had done to it and the only thing on it original as its shadow. fdsthanks again will

No, 170k isn't that much on these engines. Keeping the body and frame from rusting away is sometimes challenging. Mine has 204k, and it's all original.

Jack

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