I have a 91 gt auto tranny after putting on mac shorties offroad h pipe and bullit straight through mufflers then turnouts on all with clamps car ran fine. Took clamps off and welded it all. Now there's not as much power as before but once you hit 3800 it picks back up and can even hear a change in the exhaust. I figured maybe the guy didn't ground it right and screwed up computer. All sensors computer and fuel parts have been replaced except pump 30lb at idle 40 when u crack on it. 38 with vacuum disconected n pluged where did the bottom end power go

 

30lbs at idle is low, but usually pressure drops alittle when throttle is applied, well on my car it does. Might want to post this in the Fox section, alot of guys there that know more than me. Good luck

 

My pressure goes up to 40 then comes back down to 35 when driving. The plugs are white/grayish. Before the exhaust was very rich now seems right where it should be

 

Basically powerbrakes fine. Before exhaust was welded from a stop and you stand on it the tires would break loose and a soda bottle would flip out the cup holder. Now the tires don't brake loose and a soda bottle doesn't move but once you hit about 3800rpm it feels like someone hit a 50shot of juice and the exhaust sounds totally different

 

Yeah, maybe something got fried when welding exhaust, never a good idea to leave computer plugged in when welding. Can really open a can of worms. Have you tried pulling codes? Might narrow it down alittle.

 

All sensors and computer were replaced and no codes aftr checkin and dumping the codes

 

Ok, well then maybe the pump did take some stray voltage from welder, or something contolling pump or fuel delivery. I'm no expert on this. Only thing that sounds funny is the low pressure at idle, then pressure increases with throttle. Fuel pressure should be around 38 at idle, then should momentarily drop when throttle is applied. Do you have the pressure gauge in the car? Does it hold 40psi at full throttle?

 

At idle pressure is 30-32 if I crack on it quick it jumps to 40. If I disconnect vaccum and plug the port it is at 38-40 at idle right now I have a harbor freight gauge so not sure how accurate it is. And I'm glad people agree on here that stray voltage can damage electronics I was on stangnet forums and was told by sn certified tech that never happens

 

I finally got a new code reader. No codes only 11 system fine, did onboard cylinder check got code 90 which is all cylinders good, timing is at 16 with plug undone, tps is 89v and 4.64 at wot. New adjustable fp regulater, 40 conected, 45 disconnected n pluged, plugs grayish white

 

Is it fixed? Can't tell if your still having problems from your last post. 16' advance is up there, have you tried backing that down to the stock 10'? Other than that the only other advice I can give is repost this in the Fox section, you'll get alot more help.