Truck keeps shutting off

[mac]

Maybe someone can help diagnose my problem. All summer I've been having problems with the truck randomly shutting off going down the road; and then it won't restart unless it sits for hours. It started when I changed from an electric fuel pump to a carter mechanical pump. Got it towed home once or twice. I figured it was vapor lock so I switched to fuel hose. Then I tried running the electric and the mechanical pumps simultaneously. Now I'm back to just the original electric; which has worked fine for years but it did it again. I have taken the top off of the carb when this happens and there is always fuel in the bowl. However if you press down on the float a bunch of frothy fuel comes shooting out. Is that right?

[castruck_1964]

nope you are getting vapour lock / gas boiling in the line

[slick4x4]

I had a truck that ran like crap
I could NOT figure it out
Seemed like it ran short of fuel
Took the line off at the carb
The electric pump shoved plenty of fuel there
After doing many other things
I swapped another fuel pump on
BINGO ! ... ran perfect !
The pump would pump ... but zero pressure
I would do 3 things
Check the lines from tank to pump (sucking air ?)
Filters .... (I doubt it's this , but it's cheap)
New quality fuel pump
I buy the heavy duty ones at NAPA (about $80)

[redstone65]

Maybe a carb spacer would help? Also, I wonder if the gas tank has a venting issue.

[mac]

Thanks for the input. I also did new cap and plug wires. Does anyone think it could be the coil or something?

I'm going to buy a fuel cap to eliminate that and do a carb rebuild (it's been a couple of years.) If that doesn't get it i'll try a new electric pump. That seems unlikely because it does the same thing with a brand new mechanical pump or the functional old electric. The fuel hose is all pretty new. It has a spacer between the carb and intake manifold.

[ThinLizzy13]

Ignition related could be possible. How old is your coil?
I had a 65 with a 352 that randomly started acting up like you describe. I thought I had vapor lock. Turns out my starter was getting too hot and didn’t have enough oompf to restart the engine without it cooling down. Heat shield around the starter fixed my problem. Although mine was a different engine with aftermarket headers hugging the starter....

[fmartin_gila]

Symptoms of a coil going south on you.

Fred

[fmartin_gila]

Symptoms of a coil going south on you.

Fred

[fmartin_gila]

Don't know, but somehow managed to double post.

Fred

[mac]

So I ordered a coil and am in the middle of rebuilding the carb. When I pulled it off the phenolic spacer cracked. Can't find the right replacement anywhere. Holley makes a similar one but according to some guys on FTE it causes vacuum leaks. Anyone know where I can get one?

[mongrot]

If you can see gas spraying from the accelerator nozzle when you look down the carb with the air cleaner removed and work the pedal linkage and it doesn't fire up again it's spark related. My guess is coil. Might have spark, but not enough to run.

[oldsmiley]

I'd also look into the coil as possibly being your problem. I had a friend with the same problem. I told him to bring it over and I'd check it out for him (we're not too far apart). About 15 minutes later he called and said he didn't make it, it cut off and he was on the side of the road. I got my car hauler and headed his way. When I got there, the first thing I checked was the carb (a local mechanic who mainly works on late model cars told him he needed a NEW one).
Looked over in the carb, he hit the accelerator, and 2 streams of gas shot out as it should, so I told him to try and start it. It fired right up so I told him I'd follow him on to my place. We didn't quite make it, it cut off again with less than a 1/2 mile to go.

This time I checked the carb, and had the 2 streams of gas again. Then I started to remove the distributor cap, and in the process my arm gently came in contact with the coil, and QUICKLY came back OFF the coil. It was so hot it burned the hockey out of me (don't try this at home). I asked if he had a bottle of water and he did behind the seat. I poured it on the coil to cool it off, and and it fired right up.

When we got to my place, I had a parts truck around back, so I took the coil off that and put it on his truck and it hasn't stopped since.

It very well could be.