Fuel Pressure Drop?

[Split 1]

I am running an electric pump, have a holley guage and when I start the engine which has twin 40mm Dells with 38 venturies/chokes, the Holley guage reads 4 lbs pressure, after about 5 mins it reads nothing, the carbies still work, ( we are waiting on some jets but it runs) why would the presure drop, I switch the motor off, it still stays at less than 1 lb pressure.
Have changed the pump, have cleaned everything???
Come back to the engine in a hour os the next morning, first switch the ignition on the guage reads 4lbs, start engine same again??

Any ideas???

Dave

[sturgeongeneral]

Have you cleaned the screen in the bottom of the gas tank? Sounds like you have restricted flow.
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[Split 1]

Yes, even replaced the guaze sock in the tank and fitted a new in-line filter??

Dave

[Guack007]

You checked the floats?

[Split 1]

No havent checked the floats, ,,,how would that alter the pressure??

Thanks
Dave

[A.J.Sims]

vapor lock?
Take the cap off and retest!
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[Split 1]

Tried removing the cap, no change ????

Dave

[SGKent]

it could be just a bad sender.
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[Split 1]

Tried new carbies, no change.
Tried squeezeing the pipe needle goes up??

Dave

[Split 1]

If you come out to a cold engine, switch ignition on and pump, I get 4psi, then drive for 10 mins get 1psi but it still drives.
Guage working fine when you squeeze the fuel pipe ,the needle moves???

Dave

[JustBarry1972]

Hi, i found this thread looking for a fix for my fuel prob... i drive about half a mile and run out of fuel - ie coughs and splutters, i jump out and with engine off give the throttles a blip (dual dells) and no fuel squirts from any barrell.
I wait a while for the fuel filters to fill before and after the pump to fill up (5 mins? ) then blip the throttles and see fuel from all.
ive rebuilt the carbs twice without finding any dirt. Ive replaced the fuel pump as it trickles into the empty filter pre mechanical pump.
ive left my car with the front jacked so the tank is above my carbs (cars raked when diving)
will the filters ever stay full once filled? or do they allways turn to vapour?

[teamasr]

Split 1, did you find a solution to the problem? My motor seems to be doing the same exact thing. Running duel webers, holley regulator, liquid filled gauge and electric pump. After a minute of idling, pressure drops to zero or near zero with engine running, but exhaust starting to make popping sound.

[Split 1]

Sorry never did fix it and it carried on driving?
Since sold it so not sure what it was

[modok]

The first thing I think if I hear "pressure falling" and "liquid filled gauge" in the same sentence
is
The gauge is leaking internally.