Installed an afpr in a 91 L98 and relocated the MAT. Set pressure to 55 psi with the vac. disconnected, ran ok for 2 days, then today on intermittent hard throttle runs it acts as if either fuel or spark just dies, killing the engine. Let her coast for a few seconds, then fire it up in Neutral and its fine. I'm assuming it's fuel related since thats what i've been screwing with (and the tach still works as the car is coasting down), but can high pressure cause the pump or injector driver to cut out?

 

Your fuel pressure is set too high, I wouldn't run anymore than 50 psi. The stock fuel pressure was 44 psi on my 91 GTA 305 TPI (currently set at 49 psi) and my 92 GTA 350 TPI I just checked last weekend and stock is 46 psi.

 

yea 55 is pretty high, i have mine set to 50psi on my 87 formula 350TPI. it could be the fuel but i wouldnt think it would cut it out, it would just run rich and might affect driveability alil. have u pulled the plugs to check how they are burning? and have u seen any arcing in the ignition when the car is running?

 

Thanks guys, I dialed the pressure back to 50 psi, and it hasn't done it since. It was running pretty rich at 55 psi anyway, surging and what not. Still not sure what exactly it was though- I'm thinking a weak fuel pump that couldn't handle the extra load, but haven't seen one act like this before. Maybe higher than normal current demand was screwing up the relay or something.

 

All of these figures are with the VAC line disconnected, correct?

 

Yep