well i went to the track last night and made my first pass since installing a 255lph walbro in my car. i was running a 150 shot. i ran a 13.28 at 102 mph. . The whole pass my car was jerking while i was spraying. it ran like complete ****. my question is, what couild be the problem

 

hmmm.....my first thought would be some type of missfire and for that you are most likley running the wrong plugs gaped to big. It seems the higher shot you go the more it hates those platinum plugs we all put in our cars. Get some NGK T6 plugs and gap them to .035 (or is it .35?) from what I hear. Also, what type of condition are your plugs/opti/coil in?

 

Since your saying first time using it, check to see what bottle pressure your at. A good bottle should be 950psi(o.k)-1100psi(best). Also check your WOT switch and see if you got contact or bad ground.

Vinny

 

i run ngk t6 plugs, also my bottle pressure was around 800 i believe. It was pretty chilly out there and i don't have a bottle heater yet. Could this have anything to do with a badf fuel selenoid?

 

A low bottle will make your car jerk down the track. A bottle heater will help bring those temps up on the bottle.

Vinny

 

When you installed the new fuel pump, did you change the fuel pressure from stock? If you dont mind me asking, what fuel pressure are you running, and what jets are you using in the nozzle?