I need some help from someone wiser than myself.
‘97 Vortec 350 has me stumped. I was driving it around town, running errands as one does. I got to my last stop of the day, and upon wrapping up and leaving the parking lot became stranded. I fired the truck up, and made it about 200 feet before the engine abruptly but without fanfare died. I attempted to refire it and was greeted with the sounds of the engine trying to start but not at all in a healthy way.
Here are specifically the symptoms I’m seeing:
Free cranking, sputtering but no running
Ether/starter fluid leads to a large fireball out of the throttle body
Gas directly in the intake leads to a backfire
Here’s what I’ve checked so far:
Fuel pressure, 60psi, and does not bleed off. (Not a blown regulator diaphragm)
Spark happens, at least on cylinder 1
Distributor turns, so timing chain is still there supposedly.
Low compression on 1-3-5-7 (60psi)
Cylinder 2 is at 115psi, 4 is at 60. I have not checked 6 or 8 yet.
Plugs were a little wet, from cranking so much with no running I suppose.
Distributor is tightly held down, the base does not turn.
The cap and rotor are brand new Accel parts. The coil is a brand new MSD coil. Plugs wires to match.
I think, somehow, my 25k mile rebuilt motor jumped time. With no tensioner in there I don’t have the foggiest clue how that happens but, if it quacks like a duck and waddles like a duck…
I used a code reader and got no codes displayed, and the data reads on all sensors I recognize. MAP, MAT, CTS, TPS, MAF, RPM, all read normal and respond under cranking.
The only other thought would be a bad distributor / cam sensor pickup. I don’t know how these respond and determine crank timing but if somehow the distributor pickup was giving poor data perhaps it could advance the timing enough to cause the fireballs on ether?
I am absolutely stunned but I am out of ideas. This truck is my daily right now, so getting it fixed is a priority for me. Where would those long in the tooth go from here? Check my work again? Tear into the top end and look? Leap into a river? Any guidance is appreciated.
‘97 Vortec 350 has me stumped. I was driving it around town, running errands as one does. I got to my last stop of the day, and upon wrapping up and leaving the parking lot became stranded. I fired the truck up, and made it about 200 feet before the engine abruptly but without fanfare died. I attempted to refire it and was greeted with the sounds of the engine trying to start but not at all in a healthy way.
Here are specifically the symptoms I’m seeing:
Free cranking, sputtering but no running
Ether/starter fluid leads to a large fireball out of the throttle body
Gas directly in the intake leads to a backfire
Here’s what I’ve checked so far:
Fuel pressure, 60psi, and does not bleed off. (Not a blown regulator diaphragm)
Spark happens, at least on cylinder 1
Distributor turns, so timing chain is still there supposedly.
Low compression on 1-3-5-7 (60psi)
Cylinder 2 is at 115psi, 4 is at 60. I have not checked 6 or 8 yet.
Plugs were a little wet, from cranking so much with no running I suppose.
Distributor is tightly held down, the base does not turn.
The cap and rotor are brand new Accel parts. The coil is a brand new MSD coil. Plugs wires to match.
I think, somehow, my 25k mile rebuilt motor jumped time. With no tensioner in there I don’t have the foggiest clue how that happens but, if it quacks like a duck and waddles like a duck…
I used a code reader and got no codes displayed, and the data reads on all sensors I recognize. MAP, MAT, CTS, TPS, MAF, RPM, all read normal and respond under cranking.
The only other thought would be a bad distributor / cam sensor pickup. I don’t know how these respond and determine crank timing but if somehow the distributor pickup was giving poor data perhaps it could advance the timing enough to cause the fireballs on ether?
I am absolutely stunned but I am out of ideas. This truck is my daily right now, so getting it fixed is a priority for me. Where would those long in the tooth go from here? Check my work again? Tear into the top end and look? Leap into a river? Any guidance is appreciated.
Last edited: