Is This Vapor Lock?

[septantrionalis]

My truck has actually been running pretty good until recently.  The temperatures have been in the mid 90's and I notice that the first start in the morning goes great.  The truck fires up and runs perfectly.  I'll drive to the grocery store, run inside for about 5 minutes, and come back out.  The truck is harder to start and once it does, it wants to die.  I have to keep giving it gas or it will stall.  After a few minutes, it starts to run smooth again.

However, if I let the truck park for a longer period of time (like when I go to work), I don't have this initial start idling problem.  The truck runs fine.

[SkinnyG]

I have something similar.  A hot, short shut down, and the fuel in the carb boils and floods the engine.  Crank the engine at half-throttle to blow out the fuel, and it's usually good.  Sometimes it stalls as I'm leaving the parking lot.

I have another theory, in that the fuel between the pump and the carb might be heat soaking and pushing itself into the carb, thus flooding it.  I bought a short bit of header wrap, and will wrap the fuel line to see if I can keep heat out of it.

[blazer74]

If you have to hold the pedal to the floor to get a start then the carb is flooding.

The problem is compounded by ethanol in the fuel

Expanding hot fuel in the lines overcomes the float needle/seat.

[VileZambonie]

My truck has actually been running pretty good until recently.  The temperatures have been in the mid 90's and I notice that the first start in the morning goes great.  The truck fires up and runs perfectly.  I'll drive to the grocery store, run inside for about 5 minutes, and come back out.  The truck is harder to start and once it does, it wants to die.  I have to keep giving it gas or it will stall.  After a few minutes, it starts to run smooth again.

However, if I let the truck park for a longer period of time (like when I go to work), I don't have this initial start idling problem.  The truck runs fine.

Need to give more information about what we're working on here or it's a random guess.

[septantrionalis]

Need to give more information about what we're working on here or it's a random guess.

Good point.  I didn't put ANY information down as to what I am driving.  Its a 1974 Chevy K10 with the original 350 engine (rebuilt) and an Edelbrock carb.

[sbx22]

Wouldn't hurt to put in a carb spacer if you don't already have one to help insulate the carb.

[Irish_Alley]

is your choke working? also i dont see how vapor lock would affect the engine once shut down. the reason for this is no matter what you will still have fuel in the carb. if the lines vaporizes and is forced into the fuel bowl afaik theres vents to allow the vapor to escape just as if you park a carb for a long period of time the fuel in the carb will evaporate via the vents. so even if the fuel lines all run dry or vaporize you still have the fuel bowls filled and will run the engine for a little bit of time before they dry out and by then the vapor should bleed out of the system. but this is my uneducated opinion 

[amplifiedsilence]

Wouldn't hurt to put in a carb spacer if you don't already have one to help insulate the carb.

I was having a similar issue with my 350 and edelbrock carb. I got a spacer and it ran excellent afterwards.





from Amazon: https://www.amazon.com/Edelbrock-EDL-8723-8723-Carburetor-Spacer/dp/B003D2BXC6/ref=sr_1_1?ie=UTF8&qid=1470283091&sr=8-1&keywords=Edelbrock+8723+1%2F2%22+Carburetor+Spacer

I also had to get this adapter: https://www.amazon.com/Edelbrock-2732-Carburetor-Adapter/dp/B000630JXY/ref=pd_sim_263_5?ie=UTF8&dpID=51o75UVZfmL&dpSrc=sims&preST=_AC_UL320_SR294%2C320_&psc=1&refRID=458C0WAY2X00VEENHXMD

Needed to go square bore to spread bore for it to work with my intake manifold.

[blazer74]

Wouldn't hurt to put in a carb spacer if you don't already have one to help insulate the carb.

Wood or phenolic  will help with the heat  problem at the carb. Mostly with hot start problems and fuel boil off.

I also have one under my Qjet and it is an improvement but not necessarily a fix all.