Hi guys, newbie to the 4th gens but not to wrenching..just picked up a 95 T/A with a powerdyne 4 psi supercharger on it. Car is running poorly, have to keep winging the throttle to keep the engine running, and I think I know why. I found under the car it looks like a 2nd fuel pump was spliced into the fuel line ahead of the in tank pump. This 2nd pump is dead, and the in tank pump is pushing through it, or trying to. I dont like the idea of the 2nd pump. Was this something that would of come with the powerdyne or someone's bandaid to get fuel pressure up? Does a powerdyne need an aftermarket in tank pump (walbro?) or will the factory pump alone be ok? The car supposedly has I believe 30# injectors and does have an adjustable FP regulator. Does the regulator need to be boost referenced to bring up the FP under boost, or is the stock 45psi or so ok with only the 4.5 max boost? I am new to supercharging but want to set this up right so it is a reliable driver. Does it make sense that the car would run like crap trying to push fuel through a dead pusher FP? What is a safe fuel pressure to set the reg at to avoid going lean under boost? Thanks for any advice!

 

First thing to do is to see what your fuel pressure is by putting a fuel pressure tester guage on the shrader valve on the fuel rail. Stock pressure is 38-43.

Next thing to do is find out why your second pump is dead. I'm assuming this is an inline out of tank pump that splices in just before the fuel filter. Check the wiring because these are usually pretty reliable.

With your current setup about 50psi at wide open throttle at full rpm should be plenty.

No need to change your fuel setup if both pumps can be made to work. If the inline is truly dead then get a racetronix single intank walbro 255 setup and ditch the inline. The stock intank pump(205 lph) and wiring is inadequate for your setup by itself.

Do a search on here. There is tons of info.

 

thanks for the reply..I will test the 2nd inline pump, reason I think it is dead is the power wire for it basically got so hot it melted its insulation and burned in half. I assume the pump shorted and whoever wired it did not put a fuse on the circuit. If I do get the setup working is there a way to have the regulator referenced to the boost, or should I just set it to 50 psi at idle?

 

I don't know what kind of regulater you have.

No it does not have to be boost referenced. However, If you change the fuel pressure its gonna need a mail order tune.

You'll be shooting in the dark changing your fuel pressure without a wideband and proper tuning.

See how it runs after you fix your fuel pump. Chances are the previous owner had it tuned already for the 30lb injectors

 

Thanks again, I was going through some receipts and couldnt find one for the regulator, all I can say is it is anodized red lol..I will have to look at it. The shop put a pressure guage permanently off it so seeing the pressure should be easy enough to do, I just cant see it with the engine running because it wont idle on its own, acts like a vacuum leak, but I am hoping it is a fuel pressure issue because of the dead booster pump. Could low fuel pressure cause an engine to run like this? It starts and runs but you have to keep the throttle open to keep it running. I also found out the supercharger is in fact the 6psi version so the inline booster pump came with the install kit. Guess I will just have to get another one from powerdyne..I will bench test it but I have to assume it is shorted because the power feed line was burnt to a crisp. I was told by the previous owner that the car was not tuned, the parts were put on and ran as is. There is also a crane ignition box, a HI6, but I do not think it has a boost retard, not sure if that is needed with only a 6psi unit..and from reading the archives it looks the actual boost is probalby only 4psi. I will fix the fuel pump and go from there.

 

You could just remove the dead pump and if it idles ok then you'll know its your problem.

BTW I have an inline booster pump that I pulled when I put my dual walbro in. Its a procharger TREX pump that only has 3000 miles. It has quick disconnects to easily install by the fuel filter. I payed over $200 for it. I'll sell it for $125. All you would need is a lt1 hotwire kit from casparselectronics.com to hook it up. That would also replace the crappy factory wires used on the stock pump and it has an additional output for the TREX.

 

Cool, I will test the pump this weekend, if it is dead I will be interested in the one you have there.