Author Topic: 1985 K10 MPFI Install Check Engine coding  (Read 688 times)

Offline Bryan

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1985 K10 MPFI Install Check Engine coding
« on: June 10, 2016, 04:05:17 PM »
Hello all.  Please excuse if a duplication or if I didn't catch a duplicate posting.  I have a 1985 K10 4X4 I've owned 29 years.  I replaced the original 5.0 motor with a crate 5.8 355 and had an MPFI system installed on it.  All was going 'ok' but for some reason the check engine light that came with the new MPFI system lights up exactly when the engine gets to full temp and stays on.  I had every upgrade (motor, full tranny rebuild, 1-ton axles, etc) done by mechanics over the years (I work for an air line and am in no way a mechanic or have the time) and it seems your local typical shop stares at me like a deer in headlights since this isn't a typical problem to work on.  I was told the MPFI system (bought it brand new all the hardware for it) is based on a 97 Chevy which supposedly was a change and transitional time away from typically carb'd motors.  Once the check engine light comes on 'supposedly' the MPFI goes into some kind of 'choke mode' and the injectors I guess go to max pressure and my fuel mileage is on par with a dang Abrams tank.  I live just outside of Atlanta so I've got options in a larger city but I guess I'm looking for advice on where I might consider for a starting point to determine what the problem is and get it fixed.  The truck is my 3rd vehicle (I have a car and a motorcycle) but I'd still like to drive it more.  The whole intent behind the MPFI ($2,000.00+) was improved reliability and efficiency with today's ethanol fuel giving the old carb a fit.  Any input would be appreciated.  Again, apoligies if this is a duplicate some where but there were too many topics to filter through.  Many thanks to all.
1985 Chevrolet K10 4X4
5.8L 355 C.I. Small Block w/MPFI system.
700R4 built/rated 650hp/650lbs
14-bolt 1-ton rear with 12-bolt from from matching set obtained.
aluminum/copper upgraded cooling system
155K original chassis/less than 10K on motor/trans
short-box std. cab

not sure what other basics might be important.

Offline LTZ C20

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Re: 1985 K10 MPFI Install Check Engine coding
« Reply #1 on: June 11, 2016, 01:27:37 AM »
Does it have a code set in the ECM?
LTZ Cheyenne C20