timing problems


New Member
Apr 5, 2010
Hey, I'm looking for help. I've just rebuilt my stang 5.0 1991 gt with a v-1 supercharger. The problem I'm having is it is backfiring through the intake and reving up around 3 grand when it pops. It sounds like a lifter but it doesn't pops on every rotation of the motor, only when the motor slows about 750 rpms is when it pops or backfires. I've checked the compression and number 1 has 130 lbs, 2 has 130 lbs, 3 has 127 lbs, 4 has 130 lbs, 5 has 110 lbs, 6 has 130 lbs, 7 has 125 lbs, 8 has 130 lbs. I'm running about 6 lbs of boost. I've got the rotor button is facing number one plugwire at top dead center on compression stroke. Also when it does fire up it floods really bad, but no smoke. Any help would be great.
  • Sponsors (?)

I'd double check your vaccum lines. How is fuel pressure?

Are you running a stock motor with Vortech or a H/C/I upgrade with supercharger? Did you upgrade fuel components? What is your motor setup?
if it's backfiring out of the TB that sounds like the timing is WAY off. Set to stock i would guess and retard accordingly. all that extra air from the charger sounds like it might be throwing a sensor off and the pump is trying to compensate from the info the ecu is throwing.
I'm running stock motor with X302 heads, I had 24 lbs injectors flooded really bad, put 19 lbs on and it slowed the flooding a little bit but not all the way, I'm running the fuel pump that came with the supercharger. It might be the coolant temp telling the ecu to put to much fuel. Is there any way to check if that sensor is bad. I've got the timing stock with the number one pointing at the number one cylinder. As for vaccum lines they seem to be in the right place. The diagram off the internet helped alot. if a lifter is bad would it backfire through the intake. I'm also running an MSD dizzy set at 10 degrees before top dead center. It's brain racking.......