crazynights

iTrader: (3)

I have a HT383 with a Carter Street pump and while driving the car will start up with 6si and drop to 0...yet the car still is fully responsive and gas is still coming out. I took out the charcoal canister and took out the electric fuel pump and plugged the return. Any idea why pressure drops but the car still runs fine?
All gas lines are fine and filters are brand new.

five7kid

iTrader: (14)

Where and of what type is your fuel pressure gage?

knj8

did you ever find a cure??? my 89 formula is set up the same way and doing the exact same thing and I cant figure it out

knj8

mine is mounted on the rail and is an autometer. Ive also tried 2 liguid filled jegs gauges. Ive tried 2 carter p4601hp pumps, 3 regulators, re routed my fuel line. the pump will build 7 psi and sit there and idle and slowly drop to 3 psi then come back up to 7 then drop until it finally hits 0, and dies. It will do this while driving down the road. The line stays decently cool but the pump body gets hotter than a firecraker when pressure drops off. Anyone please help, a friend of mine has a 75 camaro and is suffering similar problems. What gives????

crazynights

iTrader: (3)

five7kid - I have an Autometer Liquid Filled guage that is mounted within my cowl hood. I also have a small jegs one in the fuel line.
The car runs fine, it does not die and still remains all it's power.
When it first gets started, it'll hit 6-7psi...then it'll slowly fall to zero..after some miles of driving.
I did remove the charcoal canister and I have that line running by my left front tire. I do smell the gas fumes...could the pressure be coming out of that?
Also I read to get rid of the sealed gas cap and get a vented one. Which model would fit our necks of the tanks?

knj8 - my fuel pump and line are all new and the motor runs fine. Also my fuel pump does not get hot.

five7kid

iTrader: (14)

Stant 11822 & 11823 are the gas caps that fit our cars. One is vented, the other is not, but I don't recall which is which (I think the 11822 is vented). The card says vented or non-vented on each one. I doubt that's your problem, but if you don't have the charcoal canister you should cap off the vapor line and use a vented cap.

Although it sounds like at least one of your gages is away far enough, reports are the gages indicate lower pressure when they get hot. My Spectre doesn't, but I don't really rely that much on it.

crazynights

iTrader: (3)

Since I converted from electric, in tank pump removed and small pickup line installed, and put on a mechanical, could it be that if the mechanical senses the holley carb bowls are full and does not force gas toward the carb?

five7kid

iTrader: (14)

The fuel pump "senses" fuel pressure, not bowl filling. When the carb isn't requiring flow, i.e., the floats have closed of the needle valves, the pump simply doesn't produce any more pressure than the 6-7 psi in the line between the pump and carb.

crazynights

iTrader: (3)

Thanks five7...so the guage should never fall to "0"...just remain at 6-7.

five7kid

iTrader: (14)

If it falls to zero, it means either the pump isn't pumping, or there isn't any resistance to flow.

crazynights

iTrader: (3)

five7 - I did some research and it's vapor lock. I've been reading some posts on here. How can I hook up a return line with my setup? Can I put a "T" in the line after the mechanical pump? The "T" going to the return?
I'll get an electric pusher pump also...but I got a chrome Holley Fuel line to the Carb...so I was wondering on the return line set up. Any tips? Thanks.

five7kid

iTrader: (14)

The threads on vapor lock pretty much went over the options.

Pusher pump is the easiest way to avoid it. Return style reg is the simpliest way to regulate pressure and provide a fuel return.

crazynights

iTrader: (3)

Thank five7 for all the help, I'll look into the Mallory or another bypass regulator and try the pusher style pump.