i have stock lp and carter 4601hp by tank, psi is 15-18 with the 2 pumps on. i I installed vulcan big line kit from carter to fuel filter no factory lp, and got 4 psi ? what gives. I put 3/8 line on from carter to ff and got 5 psi. I said *** and hooked both pumps back up, but did leave the ff to ip line and have 15-18 psi again what gives gurus.

 

I'm somewhat confused with your explanation.

You have a stock LP engine mounted?? and a carter pusher on the frame rail and you have 15-18lbs post filter correct.

You installed a big line kit from the Carter frame mounted pump into the FF and lost pressure by bypassing the stock LP correct. Put everything back together and have ~18lbs again.

Either I'm missing something or you stock LP is still wired up and you disconnected it and lost 14psi and your Carter frame pump is going out to only give 4 psi.

 

with just the frame rail lp with 1/2 in line i get 4-5 psi if i connect the two pumps i get 15-18.

 

I would say the frame pump is bad. Take the block mounted lp and move it to the frame.
I have the vulcan kit and use the 4601hp (frame mount) bought from napa and I have 15-18 psi at idle.

Other thought is that you actually have a 4600 on the frame, it is a 6-8 psi pump.

 

That was my old setup and my results were the same.

 

Sounds like a 7 psi 4600 pump to me. When I hooked my 4601hp and my stock together, I had like 28 on just the quick "WAIT TO START" cycle and decided to put on a regulator to get it around 18-22 psi. The 4601hp should definately put out more than that.

 

i know it should 15-18psi i have the 4601hp. its relayed, getten 13.4 volts ***.i guess ill have to get another, im just so sick of stinken like diesel every sunday. im gonna leave it in series for a while till weather cools. thanks guys.i think im gonna go to napa buy a new one and return this one, i bought it 2 years ago and just put it in recently.maybe summit put the 4600 in the 4601hp box.