Thread: Backfire and stalling under acceleration?

so this weekend I had something very strange happen during a race. I was in the middle of a road race and came out of a corner under hard acceleration and after a couple of seconds heard a loud bang and the car stalled, i pulled off track and killed power and tried to restart it restarted right back up i continued the lap and it back fired a couple of more times but made it to the pits. we checked a few things and found the spark plug wire a little loose to the coil so we tightened it up and went back out. Half a lap later it was backfiring again oil pressure was good and fuel pressure never fluctuated, it eventually stalled and would not restart. We pushed it up on the trailer and i had a 3hr drive home and i decided to check it before i tried pushing it off of the trailer by my self and it started right up.

anyone have anything like this ever happen? if not any ideas where to start. i was thinking ignition issue possibly. if so is there an easy upgrade to the stock ignition?

What do the spark plugs look like? What rpm were you at when you back fired? Was it the same rpm each time or just under heavy throttle?

It changed first time was high rpm, once under hard acceleration and others at low rpm just trying to get her around the track. Haven't pulled the plugs yet but they have less than 1000 miles on them

I would start with the plugs. The ignition system is pretty simple though. As long as the distributor is sealed so no water can get on the cam sensor and the condenser/ capacitor is good, there is little chance the ignition is at fault.

But if it was the plugs wouldn't it just misfire terribly? It is running great now seems like it was only happening once everything got hot.

Maybe yes, maybe no. It will tell you the condition of the fuel burn though. But, You need to go down the line and inspect everything. Plugs, wires, cap, rotor, sensor, power, ground, resistor, capacitor...

check your fuel pump relay/ pump. it might be going bad. my gti-r had the same problem.

Well the pulsar suffers from fuel starvation on hard left handers due to pump location and tank design. But if you are watching a fuel gauge while it's backfiring and there is no drop then that kind of eliminates that.

I can tell you though, when I was racing on a big airport track one time and my fuel level dropped too low, I took a hairpin left and was accelerating out when there was a loss of power and then BOOM the oxygen in the exhaust combined with the unburned fuel and blew my whole muffler apart. It dented the underside of the car it let go with such force. Thought I blew the motor until I figured out it was only happening on left handers when the fuel dropped below 1/4 tank.

not a fuel starve issue i have had that happen before on track and make sure that i have more than enough, and if that was all it was the car would have no problem restarting. i tried starting it for a 1/2 hr and all it would do was crank and not turn over at that point we just had to push it up on the trailer

Sounds like ignition issue. Replace the cap, rotor, wires, even with some spares just to test.