Vapor lock up? Running bad when warm. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Asahi123 · 07-13-2012, 05:59 PM

I have a 71 chevy 350. I have already changed the fuel pump. When the truck warms up it runs ruff up to about 30mph and then after that it runs good. Also runs great when it is cold until it gets to operating tempurater. I thought was the fuel pump changed it out. I have one of those filters you can take the filter out and clean. I have done that and replaced all rubbers hose for the fuel lines and have blown them out. I check the sending unit it looks good. When the problem starts I have tried to remove the gas gap no change. I have the origanal intake with a aluminum spacer and an edelbrock carb. So does this sound like vapor lock? I put the carb on last winter never had a problem with it sense now. It has been getting in the upper 90. So the problem didn't start until the temp started going up. Coolant temp fine. Should I put one of those plastic spacer between the intake and the alunimum spacer? Any help would be greatly appreciated.

Lee H · 07-13-2012, 06:21 PM

Is the choke opening all the way when warm?
Posted via Mobile Device

trac209 · 07-13-2012, 06:50 PM

When you pull the gascap off does it release a vacuum sound or pop off?
Posted via Mobile Device

Asahi123 · 07-13-2012, 07:33 PM

Yes the choke opens up when it is warm. No I don't any swoosh sound when the gas cap is taken off. Any other ideas? Do I need to add the phenolic spacer between the intake and the alunimum spacer?

Lee H · 07-13-2012, 07:47 PM

Thousands of these trucks are running just fine with no spacer. Need to figure out what's wrong with your setup and get it fixed. Throwing money at it in hopes of fixing will just cost you lots of money and you'll likely still have the problem. How long has it been since you have done a "real" tune up? Plugs, wires, points if you have them, check vacuum and mech advance, carb rebuild, not just throw in a kit but a real rebuild.
Posted via Mobile Device

Asahi123 · 07-13-2012, 10:25 PM

Quote:

Originally Posted by Lee H

Thousands of these trucks are running just fine with no spacer. Need to figure out what's wrong with your setup and get it fixed. Throwing money at it in hopes of fixing will just cost you lots of money and you'll likely still have the problem. How long has it been since you have done a "real" tune up? Plugs, wires, points if you have them, check vacuum and mech advance, carb rebuild, not just throw in a kit but a real rebuild.
Posted via Mobile Device

The money that was spent was 20 bucks the truck only has150,000. The fuel pump has never been changed. So I don't see were you think spending 20 bucks is throwing money at it.
Posted via Mobile Device

trac209 · 07-13-2012, 09:20 PM

Running rough when warm could also be in need of valve adjustment. A buddies car was doing the same running great when cold and bad once warm. You could try that as well in your tune up.
Posted via Mobile Device

Asahi123 · 07-13-2012, 10:19 PM

Carb is new put on 6 months ago. Spark plugs,distributer,plug wires. No vacum leaks. Timing 8deg. No issue with anything until it started getting hot weather.
Posted via Mobile Device

07-13-2012, 05:59 PM	#1
Asahi123 Registered User Join Date: Jul 2011 Location: Texas Posts: 42	Vapor lock up? Running bad when warm. I have a 71 chevy 350. I have already changed the fuel pump. When the truck warms up it runs ruff up to about 30mph and then after that it runs good. Also runs great when it is cold until it gets to operating tempurater. I thought was the fuel pump changed it out. I have one of those filters you can take the filter out and clean. I have done that and replaced all rubbers hose for the fuel lines and have blown them out. I check the sending unit it looks good. When the problem starts I have tried to remove the gas gap no change. I have the origanal intake with a aluminum spacer and an edelbrock carb. So does this sound like vapor lock? I put the carb on last winter never had a problem with it sense now. It has been getting in the upper 90. So the problem didn't start until the temp started going up. Coolant temp fine. Should I put one of those plastic spacer between the intake and the alunimum spacer? Any help would be greatly appreciated.

07-13-2012, 06:21 PM	#2
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: Vapor lock up? Running bad when warm. Is the choke opening all the way when warm? Posted via Mobile Device __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

07-13-2012, 06:50 PM	#3
trac209 Registered User Join Date: Dec 2011 Location: winnipeg Posts: 1,107	Re: Vapor lock up? Running bad when warm. When you pull the gascap off does it release a vacuum sound or pop off? Posted via Mobile Device

07-13-2012, 07:33 PM	#4
Asahi123 Registered User Join Date: Jul 2011 Location: Texas Posts: 42	Re: Vapor lock up? Running bad when warm. Yes the choke opens up when it is warm. No I don't any swoosh sound when the gas cap is taken off. Any other ideas? Do I need to add the phenolic spacer between the intake and the alunimum spacer?

07-13-2012, 07:47 PM	#5
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: Vapor lock up? Running bad when warm. Thousands of these trucks are running just fine with no spacer. Need to figure out what's wrong with your setup and get it fixed. Throwing money at it in hopes of fixing will just cost you lots of money and you'll likely still have the problem. How long has it been since you have done a "real" tune up? Plugs, wires, points if you have them, check vacuum and mech advance, carb rebuild, not just throw in a kit but a real rebuild. Posted via Mobile Device __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

07-13-2012, 09:20 PM	#7
trac209 Registered User Join Date: Dec 2011 Location: winnipeg Posts: 1,107	Re: Vapor lock up? Running bad when warm. Running rough when warm could also be in need of valve adjustment. A buddies car was doing the same running great when cold and bad once warm. You could try that as well in your tune up. Posted via Mobile Device

07-13-2012, 10:19 PM	#8
Asahi123 Registered User Join Date: Jul 2011 Location: Texas Posts: 42	Re: Vapor lock up? Running bad when warm. Carb is new put on 6 months ago. Spark plugs,distributer,plug wires. No vacum leaks. Timing 8deg. No issue with anything until it started getting hot weather. Posted via Mobile Device



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.