8683jb
Contributor
Posts: 128
Reg: 09-06-13
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09-24-23 04:54 PM - Post#2862816
Howdy all. I have a 2001 5.3L LM7 engine in a '69 Chevy pickup and recently it has started running raw fuel out the exhaust on the right side only. It runs fine but reeks of fuel and actually leaves a small puddle under the muffler inlet on that side. It threw a code for the O2 sensor so I pulled it but it and the harness tested fine. I replaced it anyway and the problem persists. I suspected a fuel injector so I listened with a stethoscope and two of them didn't sound like the other two, regarding the clicking noise they make. I pulled the plugs on that bank and two of the plugs look normal with the other two being black and wet. I assume those injectors are not closing and allowing the fuel pump to run non-stop in those two cylinders, but I would've thought it would have shown a CEL for the injector(s). I don't want to just buy injectors without knowing they are the culprit, so before I buy them I thought I'd see if anyone had any other thoughts on what might cause this. I appreciate any info! Jon
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 someotherguy
Senior Moderator
Posts: 29734
Loc: Texas
Reg: 08-01-03
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09-26-23 05:19 AM - Post#2862854
In response to 8683jb
Haven't dealt with that particular problem before, but I can strongly recommend you don't continue to run it that way as all that excess fuel will wash down your cylinders causing damage as well as diluting your oil.. and that's also enough raw fuel in your exhaust to light up your converter and melt it (if you have converters in your application.)
However, with all that said, I do understand not wanting to just fire the parts cannon at any issue - it sounds like you've got true dual exhaust on the truck since you're only getting the fuel puddle on one side as you mentioned. You could swap injectors from one side to the other and see if the problem follows, then you'll know right away if you need to buy injectors, or troubleshoot further.
Richard
| 06 Silverado ISS / 06 Silverado SS / 06 300C SRT8 / 93 C3500 dually |
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8683jb
Contributor
Posts: 128
Reg: 09-06-13
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09-26-23 06:38 AM - Post#2862858
In response to someotherguy
Swapping them side to side is a good idea. Thanks for the help, Richard!
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8683jb
Contributor
Posts: 128
Reg: 09-06-13
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11-11-23 10:20 AM - Post#2864062
In response to 8683jb
I had to delay this for shoulder surgery but now I'm able to get back at it! The truck is now throwing a P0200/injector circuit malfunction code but no P0300/misfire code. At Richard's previous good suggestion I swapped the injectors side to side and the problem stayed on the right side, the same two cylinders. A noid light showed the injector wiring to be working as it should. I swapped the right side plugs and coils with the adjacent good cylinders and again the problem stayed with #4 & #6.
So - the injectors appear to be good, the wiring appears to be good and the plugs & coils appear to be good. What else should I be looking at?
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 Shepherd
Valued Contributor
Posts: 3182
Loc: Lake George, NY
Reg: 11-11-15
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11-11-23 11:15 AM - Post#2864065
In response to 8683jb
To really pin this down it should be scanned with a high line scanner that can look at injector performance on each cylinder, such as pulse width. Do you feel a definitive misfire?. If this an afm engine they can develop problems related to this.
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8683jb
Contributor
Posts: 128
Reg: 09-06-13
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11-11-23 11:50 AM - Post#2864066
In response to Shepherd
Thanks for the reply, Shepherd. Yes, there is definitely a misfire. I'd like to get it to a shop that has more sophisticated equipment but I don't want to drive it with as much fuel as is washing down those two cylinders, so I'm trying to locate someone who can come by and check it out. What is an afm engine?
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Shepherd
Valued Contributor
Posts: 3182
Loc: Lake George, NY
Reg: 11-11-15
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11-11-23 12:27 PM - Post#2864067
In response to 8683jb
The misfire could be internal so a compression test may be required. Afm was not equipped in that year, cylinder deactivation for economy.
Edited by Shepherd on 11-11-23 12:33 PM. Reason for edit: No reason given.
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8683jb
Contributor
Posts: 128
Reg: 09-06-13
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11-11-23 08:08 PM - Post#2864070
In response to Shepherd
OK thanks again. I'll let you know how it all comes out.
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