I agree you probably have a restriction of vapor lock. Fuel filter or fuel line improperly routed alongside hot engine or exhaust.  Or an old hose breaking down internally. Avoid fuel filters on top of engine.

I find mechanical engine driven fuel pumps are the most reliable fuel system you can have.

reason for converting to electric fuel pump is that i plan on running efi, but i want these gremlins out of the way first
could be a filter.....
I had the same problem with a mecanical pump before i did the swap, suspecting it would fix the problem.... it did not
new tank new fuel pickup with filter
inline oem-ish pump for volvo 740..... and bosch 044

I had this problem before installing all these things, thats why I suddenly started thinking that there maby could be something with the carb, i am not that good with carbs, but maby?
 

i have drained the tank and replaced some hoses today with hard lines, tomorrow i will put it all together again but will blow the lines with air before putting it together...... I will take away the pre pump filter aswell, it is a cheap shitty filter, if it does the trick i will buy a betterflowing one.... I am not that scared anyway, i have the filter on the pickup tube.... if its still not doing its job, i really think it is after the fuel system, or the regulator itself

I know you drove it without the gas cap butt..........next time it quits, run and check to see if you have a vacuum in the tank!?! Sounds like the pump is pumping until it dead heads because of a vacuum in the tank/line.  Gotta be that or the filter!! IF it were the carb it wouldn't run good to begin with and THEN start  acting up.
6sally6

small update;
flushed tank, removed pre pump filter (it was a bad cheap one) disconnected all lines and blowed them clean with compressed air. put everything back together and went for a test drive....
same thing is happening. seems to be fuel starvation, because everything i have to do to get it started again is to pour some gas in the carb, then she starts right up again, keeps on going for aboute five min, and then she starves again.... fuel preassure back to normal everytime i restart her. since she stalled compleatly i did not get the chance to check fuel preassure,,, I have a feeling that this is more likely to happen at low throttle, but it is really just a guess by now.

yes i suspect that aswell...... but to be honest my head has been spinnin around electrical issue aswell..... there is a small chance that the earlier foult were waporlock, because i were missing the spacer behind the mec-pump, and the car ran alot longer then....... i will try to bypass relay and see what happens, if that does not work i will take a look at the carb i think....

Unless I missed it, I don't see anything about testing/changing the neoprene lines.  They will deteriorate and develop a "flap" that will close off the flow then open back up after a few minutes when downstream pressure or vacuum (depending on location of the flap) drops off.
And if you aren't running Alky-Safe tubing it don't take very long for them to start going bad.

BB

Last edited by Bullet Bob (9/20/2017 7:10 PM)

starting to get even more frustrated  
wired the fuel pump directly to the battery today, no relays no nothing..... she is still sick the por thing, if anything she ran for a shorter time....

Ah....what he means is a "flashlight".  LOL

BB

I think you said you have a regulator...what kind exactly?  And where is the FP Gauge connected...ahead of or after the regulator?  And...what pump are you using?  You stated that the electric pump is preparatory to going with EFI, so...what pump?  I don't think that a high pressure EFI pump would be happy in this single line, low pressure, low flow situation.

BB

Bullet Bob wrote:

I think you said you have a regulator...what kind exactly?  And where is the FP Gauge connected...ahead of or after the regulator?  And...what pump are you using?  You stated that the electric pump is preparatory to going with EFI, so...what pump?  I don't think that a high pressure EFI pump would be happy in this single line, low pressure, low flow situation.

BB

it is a return system, regulated with https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/regulators/carbureted_regulators/parts/2015
there is a efi-pump currently there is a bosch fuel pump for an old 911 or volvo earlier there were a bosch 044, both are good, and both are ment for efi, thats why I have the return line...

From the catalog -

The Mr. Gasket Fuel Pressure Regulator #2015 is a return-style fuel pressure regulator. The operating fuel pressure range is 4.5 – 9 PSI. The inlet/outlet size is 3/8" NPT. The fuel return line size should be 3/8" I.D. or larger or the regulator will not regulate properly. For use with carbureted fuel pumps only. For use with gasoline fuel systems. Not compatible with alcohol, methanol or E-85 fuels. Not for fuel injection systems.

If the pressure regulator is seeing too much pressure it might give up and go straight to bypass.  Of course, Holley could be wrong about their own product. I agree with Mike.  Ditch the pump and go mechanical to eliminate all of the other possibilities.  I would install a pressure gauge in the system temporarily to check  the actual pressure at the carb no matter which way you go.  A proper low pressure electric fuel pump may cure your ills if you are uncomfortable with a nice and simple mechanical pump.