Heat Related Stalling Issue

[gstuck3]

I have a 74 Jimmy with stock 350 4bbl. I spits, spudders and stalls when it gets hot. I don't mean overheating hot, just hot. It gets me to work just fine in the mornings (about 70-80 deg. outside temp) but will stall in the afternoon ( about 100-115 deg. outside temp) so I'm pretty sure it's temp related. Some times it just spudders and recovers if I feather gas while driving. Sometimes it dies but will crank if I just throw it in nuetral and crank it. It acts like a cloged fuel filter, idles fine but dies when you try and go, so I changed it, and the ignition control module in the HEI just in case that was it. It has the original metal fuel ling that hugs the front of the block behind the altenator and smog pump. Is it vapor lock? Could I wrap something around the fuel line to keep the heat off it? This thing has let me down a couple times 'cause when it quits it takes a while to crank, and it's hotter than dang-it out here and I have three beautiful girls (13, 8 and 2) that my wife will kill me over if they so much as break a sweat because I break down again. Thanks.

 

[rumbly truck]

does the fuel line coming from the tank go inside the frame? I have a 85 k-3500 with a 454 in it , and I have no problems with vapor-lock. The fuel line on my truck is on the outside of the frame. A mechanical fuel pump will worsen vaporing by lowering the boiling point of the fluid it is putting a negative pressure on. maybe a electric pump could help. Also a heat sheild under the carb wouldnt hurt any thing in that kind of heat. Ok dont laugh try several clothes pins on the fuel lines at several points , especially right at pump, to increase air flow, by the line kind of a heat sink if you will. hope this might help

 

[gstuck3]

does the fuel line coming from the tank go inside the frame? I have a 85 k-3500 with a 454 in it , and I have no problems with vapor-lock. The fuel line on my truck is on the outside of the frame. A mechanical fuel pump will worsen vaporing by lowering the boiling point of the fluid it is putting a negative pressure on. maybe a electric pump could help. Also a heat sheild under the carb wouldnt hurt any thing in that kind of heat. Ok dont laugh try several clothes pins on the fuel lines at several points , especially right at pump, to increase air flow, by the line kind of a heat sink if you will. hope this might help

Thanks for the info. The fuel line is on the INSIDE of the frame rail. I also have a electric fuel pump mounted on the outside of the frame just under the rear fender. It was installed by the PO. This feeds the Manual Pump. It has a 1/4 in. gasket under the carb. Is that what you are talking about heat shield? I'll try and see if we have some clothes pins too.

 

[original balzer]

do you have headers? thats the most common thing i see vapor lock from is headers the inside frame fuel lines always seam to hate header heat but its not always the case i seen some stock exh. manifolds do it too a heat sheild would be my sugestion i use a hose clamp and a peice of silver tin bent so its about 1/2" away from the exhaust pipe at the area closest to the fuel line

the other thing i sugest is you check that electric fuel pump if its not pumping enough (common) your mech pump is haveing to suck the fuel though the elec. pump and may be starveing your carb at higher rpm's

Balzer

 

[dyeager535]

Do '74's use a fuel return line? If so, vapor lock is not going to be the issue.

My dad had what was suspected to be a vapor lock issue (only happened once the engine bay heated up) turned out it was a bad fuel pressure regulator. Stupid problem, easy fix. No fuel pressure regulator with a stock mech. pump.