Electrical stupidity, please give feedback....

50

Asked by LpgMitch045 Jan 19, 2020 at 11:46 PM about the 2001 GMC Sierra 1500 SLE 4WD Standard Cab SB

Question type: Maintenance & Repair

I have an 01 gmc with the 5.3, I just did a motor swap (old had a bad oil
consumtion issue). Anyway upon completion it would crank but not start, I
followed the youtube advice and moved the grounds on back of block. It ran
ok, then three sensors went stupid, knock,tps and egr. The last was because
of a hole in the hose. I replaced all three, started it and ok, two days later just
sitting in one spot will crank and not start. I have checked and its getting fuel,
the schrader spits on the fuel rail. I don't like the grounds being in non stock
locations (maybe ocd). Anyway I was told it maybe negative cable ground.
Maybe a million other things also the CEL shows but upon scanning says no
codes found, but it identifies the truck by VIN. Please help!!!

3 Answers

103,485

Go through and make sure all those sensors are working, crank, cam, TPS, etc., crank for instance can prevent spark if it's not present. (you could also easily check you have spark.) A shop with a better scanner can check for live data during cranking to make sure all needed sensor input is good. During startup the ECU is in open loop so only a few sensors are required for spark (like crank, cam). It's not until after ECU goes into closed loop that the rest of the sensors are involved (like O2s).

50

I did check the sensors and for the most part most are new. It was running the other night but the weather turned to crap so I elected to wait until it cleared and thats when it went no start. I have a decent obd scanner, it give live feed what should I be looking for when I crank it on the scanner??

Your Answer:

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