need help injector problem

mudygmc

New member
Dec 8, 2008
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Buffalo MN
Hey guys I need a little help.
Last thursday I was driving to my cabin 90mi. And thought I could hear an injector getting louder. No foresure but sounded like I would get a little more timing rattle the more times I accelerated. I pulled into the driveway and put it in park so I could unlock the gate. When I went to put it back in gear my foot was on the brake only. When I shifted to drive the truck took off. I was doing 5-10mph instantly. It even spun the tires. I was amazed I hadn't even touched the gas pedal. I lurched for 30-40ft then ideled down to normal. I put my foot on the gas pedal and started to accelerate. I looked in the mirror and noticed a big cloud of grey smoke and that it was rolling out white/blue smoke as I drove. The truck didn't make any unusual sounds the whole time. I drove 200yds up the driveway and parked it. I had my computer with so I checked balance rates, as I thought I had an injector stick open. When test the rates #'s 1 3 4 5 6 7 8 were all -1 to -4 mostly -2 or -3, but my # 2 was holding solid at 15. I don;t totally understand what the balance rate #'s mean so I assumed that # 2 was sticking open. I had my dad bring up a new injector. I put my 40 over nozzle on the new injector and put it in. I checked balance rates again with the same result. The only other thing I could think of is it might be shotring out. I checked the harness the best I could and couldn't find a short. I left the truck at the cabin affraid to drive it. I need help. I don;t know what is wrong and need some ideas.
 

bullfrogjohnson

Big Girl!
Nov 20, 2006
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Only time I have ever seen a balance rate of 15 is when there is a cylinder issue. I have seen it two times and both times it was a cracked piston.

You need to do a compression test on cylinder 2.
 

mudygmc

New member
Dec 8, 2008
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Buffalo MN
Only time I have ever seen a balance rate of 15 is when there is a cylinder issue. I have seen it two times and both times it was a cracked piston.

You need to do a compression test on cylinder 2.

I have a standard compresson tester, Will this work? I assume you test by pulling out a glowplug? What psi should I look for. Everything is stock in there except for studs and series C gaskets. Would the piston crack with just putting it in gear? It didn't smoke at all the whole drive up to the cabin. I might try to get up there sometime this week otherwise next weekend. I would like to come with a bunch of ideas to try.
 

bullfrogjohnson

Big Girl!
Nov 20, 2006
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I have a standard compresson tester, Will this work? I assume you test by pulling out a glowplug? What psi should I look for. Everything is stock in there except for studs and series C gaskets. Would the piston crack with just putting it in gear? It didn't smoke at all the whole drive up to the cabin. I might try to get up there sometime this week otherwise next weekend. I would like to come with a bunch of ideas to try.

I standard tester will work but you need the right adapter for the glow plug. You need to see around 400psi
 

mudygmc

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Dec 8, 2008
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Buffalo MN
anybody remember what thread pitch a glow plug is? I will go and buy an adapter. I hope it isn't a piston. I don't have the funds right know to do much.
 

mudygmc

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Dec 8, 2008
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Buffalo MN
A compression tester kit can be bought from Harbor Freight for about $27.00. Compression should be in the 400 psi range.

I have a nice compression tester. I was curious as to the thread pitch for a glow plug to see if I had the right adapter or needed to get one.
 

JoshH

Daggum farm truck
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Feb 14, 2007
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I can't remember for sure. I think the glow plugs are 10 x 1.5, but I'm not positive on that. You can pull the glow plug and check the pitch with a bolt at a hardware store or something. They're really easy to get out. Have you tried moving the injector to another hole to make sure it isn't something with the tip?

Isn't #2 one of the injectors that commonly has problems with the harness?
 
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mudygmc

New member
Dec 8, 2008
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Buffalo MN
I can't remember for sure. I think the glow plugs are 10 x 1.5, but I'm not positive on that. You can pull the glow plug and check the pitch with a bolt at a hardware store or something. They're really easy to get out. Have you tried moving the injector to another hole to make sure it isn't something with the tip?

Isn't #2 one of the injectors that commonly has problems with the harness?

If I tried the stock tip on that injector with the others being 40 overs would there be a significant difference in balance rates? What could happen to the tip? It looked fine when I switched it.
I was doing some research and it looks like it could be the harness. The way it acted I don't think it is a broken or cracked piston. It seems to run smooth other than rolling out lots of white/blue smoke. And it happened when I put it in gear. With no unusual sound. What kind of tester do I need to plug in to the harness and test it? The truck is 90mi away and when I go back to the cabin I want to have plenty of options to try to figure this out.
 

mudygmc

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Dec 8, 2008
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Buffalo MN
Hey guys I've been thinking alot about this. Is it possible I could have a cracked nozzle? I don't really know how an injector actually works, but the nozzle was switched from the old to the new injector. It was at my cabin and I didn't have any cleaner so I wiped it off and put it in the new injector. I also left the origional needle in there too. The truck seems to run fine while blowing the white smoke. It sounds normal. I think it would sound different with a cracked piston. Would it smoke with a cracked piston? I am running 40 over nozzles what would happen to the balance rates if I put on the factory nozzle? Could I possible limp it home on a factory nozzle if this is the problem? Does anybody know of an injector schematic?
 

S Phinney

Active member
Aug 15, 2008
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It is definitely possible you have a cranked nozzle. You would have to clean it gently and look at it with a magnifying glass. Don't use anything abrasive on the tips though.
 

bullfrogjohnson

Big Girl!
Nov 20, 2006
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You need to check for blowby when the engine is running. Remove the oil cap before the engine is started and after the engine is running check for smoke.
 

White Duramax

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Jun 25, 2008
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ohio
I have seen LLY injectors go +15, it got water in the fuel and ended up ruining several injectors, if that was the case it would have fixed it replacing the injector. I would try the ice pick fix on the connector. Did it throw any codes? Just saw how old the OP was. Are you having a similar issue paint?