Ls_Notch

I have the msd box in my ls swapped fox and when I first got it running it ran perfect then all of a sudden it started popping and back firing through the carb. Now when I try to start it is doing that as well. Ive put new cam and crank sensors in, checked the grounds, have a good pos power right to the box and tried a buddies set of coil packs with no luck. Does this sound like a bad box to you or am I going crazy?

The stunningman

iTrader: (47)

Wonder if the reluctor wheel has messed up somehow. Do you have a callies crank? Did you build the engine with a different crank? Also some boxes had to have wires flipped on the cam sensor, I believe.

3pedals

iTrader: (3)

My 6012 was doing that. I went through all the trouble shooting stuff, and in the end I took the front cover off and found my cam was 1 tooth advanced. I am 99% positive I installed it correctly...... The engine ran perfect for about 2 months before a hard backfire, afterwards it was hard starting, and prone to backfiring upon startup. I feel stupid if I installed my cam 1 tooth out, but I really think that happened with the hard backfire.....
I put a new cam in the engine and made SURE it was installed at the correct ICL, and so far it starts excellent. - Same MSD box.
Might not be your problem, but worth a look.
Barrett

Gee101

iTrader: (8)

Have you checked to see if your getting spark? check for spark and take a look at the plugs. Could possibly fouled your plugs and flooded the engine.

Ls_Notch

It was the plugs, I put a new set in a few passes ago and I must have had one foul or just be bad, put all new in and it fired right up, pretty bad when the simplest things get you stumped!

3pedals

iTrader: (3)

Good news, take the easy ones when they come!