Fuel, Pulse, ECM signal to fumps and tbi solinoid

Tiny
POLICE1
  • MEMBER
  • 1989 GMC SIERRA
  • 7.4L
  • V8
  • 4WD
  • AUTOMATIC
Truck was running, left it sit for 2 years. No fuel at tbi, changed pumps no fuel at tbi, pumps do not come on checked system grounds, engine will run by pouring gas down tbi. Changed ecm, same condition. All other sytems working fine. Check engine light, shows troubel codes 12, 13, 14, 15. Checked fueses, wierring, every thing, even put carb on and it ran. Changed oil pressure switch, and coolant temp switch, im thinking power at relay but no signal going to pump and tbi soliniod. Relay good.
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Saturday, October 10th, 2015 AT 9:28 AM

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Tiny
HMAC300
  • EXPERT
This may be a bad coolant sensor or shorted wire to it or ecm. Check with the pics i'm sending. Check yellow wire for short to ground. These used to go bad along with the wiring and a short piece of harness was given with sensor to replace as coolant would leak up into the ecm though the wire. DO NOT USE SILICONE to seal new sensor, it may already have a sealant on it.
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Saturday, October 10th, 2015 AT 10:12 AM

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