AboutCAJUNSC/RAMBLER390 Expertise 1998 and NEWER questions ONLY!! I WILL REJECT QUESTIONS FROM 1998 BACK. Electrical diagnosis. Brake Diagnosis. Driveability, Service Engine Soon Lights. Some Engine mechanical. Tires and wheels. ABS. HVAC. Air Bag (SIR). Interior, seats, etc... 6.6L Duramax Diesel diagnosis. 6.5L diesel diagnosis. I WILL not answer Alignment questions OR carburetor questions. No heavy internal transmission
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I work at a Large, Busy GM Dealership
Last thing, my answers are JUST SUGGESTIONS and ADVICE and you should ALWAYS CHECK with your mechanic for proper diagnosis and repair.
Experience 18 Years GM Dealership experience as an "A" line tech. ASE MasterTechnician. 100% GM certified MTC Certified.
Education/Credentials High School graduate. No College or higher learning.
Expert: CAJUNSC/RAMBLER390 Date: 1/4/2008 Subject: Safari will not start
Question Hi!
I have a 99 GMC safari 4.3. Engine cranks fine but will not start. Fuel pump is not coming on. Checked relay and it is not activating. 1 terminal has 12 volts constant. Terminal which should have power for a fer seconds when ign is turned on/off has none. I ran a jumper wire to power pump and it ran. 1/2 tank of fuel. Tried to start but only would crank. Checked for spark, it is good. Checked eng fuses all good. Checked for power to injectors and all pink have power with key on. Put test lite to ground and other end to other wires on injector plug while cranking all six flashed. Did not check fuel pressure yet but fuel did flow out port when I had pump wired to run. Fuel pump was replaced a year ago and ignition switch 4 months ago. Thanks and have a great day!!
Answer Hi
I would FIRST see if the "security" light on dash is on. It IS possible the vehicle is in VTD Fuel disable mode.
IF this checks out, I would then check the system thusly,
The 4 terminals for the pump are B+, fuel pump B+Feed, fuel pump control (from VCM), and ground.
If your are not getting power on pump control, then I would check Ckt.465 from VCM to relay. If it checks OK< I would then See if I am getting a Distributor pulse reference TO the VCM FROM the distributor. This is where the Pump control originates. A Scan tool will HIGHLY aid in this. Other than a scanner, You'll need to check for ac current from the Dist to the VCM.
(It is possible the Cam sensor inside the distributor if faulty. It is replaceable by itself.)
If you have electricl experience no problem....If not I would then HIGHLY recommend taking it and having it checked professionally.
You REALLY should make sure pressure is 60-66 psi. Any less and this system will NOT start.
I hope this helps
Pawl
