fuel problem

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aaronk785

aaronk785

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Lately my car has had a fuel delivery problem. Its fine for about the first 10 minutes. Runs through the gears just fine shifting at 6500. By 15 minutes or so at about 5000 it falls on its face and then recovers in a couple seconds. I figure this is when the fuel bowls empty and not refilling fast enough. So i checked my gauge after the engine was good and hot. Pressure was between 1 and 3 lbs. When its cold pressure is about 7.5 to 8. Pump is carter mech. strip pump which kept up just fine with dual quads on my t-ram. Now holley 750. for last 2 years. Never had this problem before.
 
try non alcohol gas, run the tank down fill it up a couple of times then test again.


I had same problem (not at high RPM but under load like starting from a light on the street, stock 273 2bbl) only when hot out side or idling for prolong periods of time (drive through lane) then relatively normal startup from a light.

I could watch the "phenomena" happen at idle. I had a clear filter, hot engine, filter fuel level would slowly drain down to nothing (pressure would stay at about 7 or so), engine rpm would start to drop (pressure would start to drop to 3ish) then pick up as the filter started to refill (pressure would return to 7 ish)

doesn't happen with non alcohol fuel!
 
Thanks 67. I’ll give it a try. I always run 91 but but mix in 87 cause we don’t have 91 where I live. And some 91 also has ethanol. I try to fined no ethanol 91 but not always a choice.
 
My point is mostly if you do not have the problem with non alcohol gas you now know how to fix it. Return line to vent the vapors that build up from the alcohol and heat.
 
I had the same problem with my bracket car on ethanol based gas, I now only run non ethanol fuel & I've had a return line since the car was built.
 
Dana, that listing in Texas is mostly marinas & the fuel docks are on the water. They frown on fuel cans the last time I went to one.
 
when was the last time you checked / changed the fuel filter?
 
True. I have one to try. Might have hood clearance problem. We’ll see.
 
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Might be time to measure the length of the fuel pump pushrod.

If that’s good I’d consider adding a lower pressure electric pump in the rear.
You might be having some vapor lock type stuff going on with the long suction length.

Something like a Carter 5psi pump or the Holley red work well in that situation.
 
Have a new one still in the box. 5.5 to 9 psi. Ordered it for my nitrous system but my system uses 10 psi for fuel so went with a Holley. I give it a try with the other mods listed on here. Thanks. No way I’m using my nitrous till this is fixed.
 
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