Car shuts off at WOT

[Brutal Buick]

A friend just bought a GN and is having a big problem. Every time he gets on it hard the car just shuts off and starts backfiring. If he eases into it it will go no problem but if he just stands on it it dies. He is ready to give up and sell it. Anyone have any ideas what could be happening? TIA

Jamie

 

[MrBoost86]

The first thing, I would check is the spark plugs. They sound like they are too hot. Make sure they are the 43's and nothing more. If they are 44's or 45's they are way too hot. I bought new plugs for my 86 GN and the ass behind the counter gave me 44's. The car ran excellent before and after about 50 miles with the new plugs I stabbed it and it fell on its face just past 7 lbs. boost. So I would start there, immediately.

 

[BoostKillsStres]

Does the car have a good newer fuel pump and adj reg on it? If not, could be leaing out and causing a bad enough lean misfire and backfire to drive terrible at wot. What chips in it? Scan data? Is it knocking? Probably a good idea to go over all the grounds on the car, back of heads, battery cables - ground to engine and make sure positive isn't shorting anywhere as thats fairly common. Then have a caspers coil/module tester put on it and see what the fires like along with the previous suggestion of checking all the plugs and wires.

HTH

 

[UNGN]

Sounds like a fuel pump to me.