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madmechanic
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Jul 11, 2012, 12:19 PM
Post #1 of 5
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engine problems
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I have a 93 GMC extend cab 1 ton daully , it used to be 6.5 turbo diesel . It has had 3 diesel engine in it and they are known to break cranks . I changed it over to gas and now have a rebuilt 5.7 TBI in it , it has 31,000 kms on it now and ran beautiful until 3 1/2 weeks ago . Now it over fueling and blowing black smoke out tailpipe , runs like crap . I have change everything I can think of , but have not put a scanner on it . I don't think a scanner will do much for me because of my wiring , it's still diesel wiring under the dash and diesel don't have computers in this yr of truck . I've put gas wiring under hood and a computer in it now , is driving me crazy trying to fiqure this out . Has anybody out there got any suggestion , HELP PLEASE .
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 18, 2012, 5:52 AM
Post #2 of 5
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Re: engine problems
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OK: Had a PM from this guy mostly I just said this is now an unknown how it is wired for what so I don't think regulars can just magically guess how some critical items are controlled now that it is gasoline.
OP = (original poster) Just one lame shot is that however wired this engine is getting info from a CTS (coolant temp sensor) and always thinks it's stone cold.
How can I or anyone know how that is hooked up or even involved now?
T
(This post was edited by Tom Greenleaf on Jul 18, 2012, 5:57 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 18, 2012, 6:59 AM
Post #3 of 5
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Re: engine problems
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He created Frankenstein and put a computer engine in a truck with a diesel. Good luck with that.
Note to OP. PMs are not for asking repair questions. They remain public record in the open forum.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 18, 2012, 7:00 AM)
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madmechanic
User
Jul 21, 2012, 4:36 PM
Post #4 of 5
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Re: engine problems
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Hi Tom , I'm a 35 yr certified licenced GM mechanic . I've done a over kill on this job , all solder and colour coded and everything works . I'm a perfection nut when it goes to my work . Chevy usely have a close colour code wiring harness and I sat down a made one from 2 harness over a period of mths . I can swear on my repution it not a wiring problem and it was working awesome until a couple of months ago .
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 21, 2012, 10:14 PM
Post #5 of 5
(2073 views)
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Re: engine problems
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"Close" is useful for hand grenades and horse shoes not for color code wiring. I couldn't have a clue with the best of info just what this would need to switch apples to oranges never mind that early 1990's were a state of confusion, mid year changes possible.
Dosn't matter how much attention you paid to soldering in wires you need to know all the items that control fuel delivery now with this black smoke and running poorly.
M.Y. (model year) 1993 still would have had plenty of of computer controls and let's not forget evaporative emissions for gasoline that wouldn't be so involved in a diesel so much or very limited.
Now a "rebuilt" TBI engine and most likely unknown what was needed to rebuild the core that came from thrown in. Over fueling could have washed out cylinders and now compression and blow-by an issue.
It ran before so best I can say is to retrace what connection or control is getting improper info AND check plain engine that it hasn't suddenly lost proper compression.
Side note: GM earlier than '93 was making diesels out of Olds gasoline blocks in a fury to boast high fuel economy for cars anyway with scads of engines that couldn't make 50,000 miles without blowing up and folks were converting back to gasoline engines and all I knew of but not involved never worked out rendering the vehicles illegal for use on public roads.
As Hammer Time mentioned this is now a "Frankenstein" truck AND ~20 years old so by nature it's a nightmare,
Tom
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