[68blkbrd]

Drove my car to work 85 degrees outside.
Car sputtered intermittently on highway after about 25 miles. Temp reads great at 180 (new
Optima 4 core radiator). Car then stalls. I check glass fuel filter it's dry. Try to start it no go. Cool it down for 25 minutes and fires up. Fuel pressure shows low 0-1 psi. Looks like fuel is just gurgling into filter. Limp it into work. Restart car at break time (cooled down) and fuel pressure gauge reads 6 psi (fuel filter full). I believe I'm getting vapor lock or something. I have a summit mechanical fuel pump, performer rpm manifold, Holley 750 vac sec carb. Happened twice now even on a cool day. Why would the fuel pressure drop so dramatically when hot? The fuel line is routed away from heat sources. Thought it may be the fuel pump but works great when cool. Timing is good. Installed a new pump today still bad fuel pressure into the filter. Installed a new fram inline filter too. Idle is ok. I checked all my lines. Popped the gas cap. No improvements.Just ran a fuel line to a gas can and still little pressure to fuel filter. That would rule out a line problem from pump to tank. Car gets enough gas to idle and run. Hell, I can even wing the throttle and still no problems so I can say the pump is working but seemingly not at full stroke. The Summit pump that was on before I had acutated by hand and am getting pressure so It's not the diaphragm. I belive I am under the cam eccentric when installing the pump. I am thinking an electric pump now but I really don't need one.
Still searching for enlightenment...No Norwalk for me.

[68blkbrd]

Drove my car to work 85 degrees outside.
Car sputtered intermittently on highway after about 25 miles. Temp reads great at 180 (new
Optima 4 core radiator). Car then stalls. I check glass fuel filter it's dry. Try to start it no go. Cool it down for 25 minutes and fires up. Fuel pressure shows low 0-1 psi. Looks like fuel is just gurgling into filter. Limp it into work. Restart car at break time (cooled down) and fuel pressure gauge reads 6 psi (fuel filter full). I believe I'm getting vapor lock or something. I have a summit mechanical fuel pump, performer rpm manifold, Holley 750 vac sec carb. Happened twice now even on a cool day. Why would the fuel pressure drop so dramatically when hot? The fuel line is routed away from heat sources. Thought it may be the fuel pump but works great when cool. Timing is good. Installed a new pump today still bad fuel pressure into the filter. Installed a new fram inline filter too. Idle is ok. I checked all my lines. Popped the gas cap. No improvements.Just ran a fuel line to a gas can and still little pressure to fuel filter. That would rule out a line problem from pump to tank. Car gets enough gas to idle and run. Hell, I can even wing the throttle and still no problems so I can say the pump is working but seemingly not at full stroke. The Summit pump that was on before I had acutated by hand and am getting pressure so It's not the diaphragm. I belive I am under the cam eccentric when installing the pump. I am thinking an electric pump now but I really don't need one.
Still searching for enlightenment...No Norwalk for me.

[Malky]

Geez, 68, you have got some good info on what is happening and have done all the right things to try to fix it. I would have suspected pulling a vacuum in tank if it only happens after a long run, but you checked for that by pulling the gas cap.
Or check valves in the pump but you tried new pump.
Or dirty sock in tank, but, if I understand you correctly, you connected pump suction to a gas can and still had the problem.
You have tricky one!
Does it only happen after a long run? Is it a Chevy or a Pontiac engine? What carb?
I suggest you post in "Drivetrain - Street" since the guys who read this forum are too obsessed with getting their Pontiacs to run cooler to give this the attention it deserves.

[transam1979]

I just went thru the same problem on my 79 TA 403.I hooked vacum back up to fuel tank and has been ok ever since. Good luck by the why It happened when I switched over to edlebrock 750 performer carb.

[78 GHOST]

I'd run a section of fuel line from the pump to the carb directly, bypassing the hard line and the glass filter. Here's why:

If I understand correctly, you ran the car from a gas can, virtually eliminating everything before the fuel pump.. if so, check for obstructions in the fuel line from the pump to the carb. It's possible you have something lodged in there.. or, it's corroded beyond belief and the ID is really small.

I've also heard these glass filters have extremely small orifices at either end. You may be fighting the designed-in restriction. I'd suggest running a simple length of fuel line from the pump to the carb temporarily to see if things improve.

-You do realize the dangers of a glass filter regarding the ease of fire starting? Although it's great for troubleshooting, you may wish to dump it when you can.

Hopefully this is of some use to you.. -Matt