truck vapor locking?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

87Lowrider · 05-22-2009, 06:09 PM

Now that the weather has gotten warmer here, i've gotten the truck out for several short trips around town.

Problem is, when it gets warm, say, 190-200 degrees setting in traffic, the engine starts to bog down when taking off. You can put the pedal half way down and no change. After a few minutes going down the road, it straightens up and power comes back. Does that sound like a vapor lock??

It's my '87 with the 454 in it, EDL 1705 carb and Air Gap intake. Thought it may be dirt in the carb but it doesn't happen all the time, just when the engine is heated up real good.

Any thoughts???

Ken

sdavid · 05-22-2009, 10:52 PM

I think a vapor lock would actually kill the engine. Or in a furd with a carb it will.

Your fuel could be boiling inside the fuel line. Under hood air temp could be so hot it is smothering the engine.

Check the fuel line to make sure it is not too close to the exhaust or other extremely hot parts.

LiveAnimals · 05-23-2009, 10:03 AM

here's something for both of ya, if the fuel is boiling that is the transition of liquid to a gas hence "VAPOR" lock. http://en.wikipedia.org/wiki/Vapor_lock

Nolowrider · 05-23-2009, 10:40 AM

Like David said, def check your fuel line routing. Make sure it is not laying on the intake or anything else that really gets hot. Make sure you fuel line is not too close to the radiator outlet, down by the mech fuel pump. Check the choke. Make sure it is opening all the way up when hot. I have seen coils ground themselves out when they get hot. If you have an external coil, where is it mounted? I don't think it is vapor lock per say, but maybe fuel perculation. When the fuel gets hot the vapors take up more space, this sometimes overpowers the needle and seat, fuel dribble down in the carb and cause flooding.

87Lowrider · 05-23-2009, 07:24 PM

All very good information... Thank you!

I'll work on it this weekend and check all that. I do know the fuel lines are close to the lower radiator outlet and the header tube for #8. So, I'm re-routing those things first.

The Carb has no choke installed. It's a manual choke 1705 but not hooked up... Thought about buying the automatic choke for it and installing it. Local speed shop carries it.

Kenny

05-22-2009, 06:09 PM	#1
87Lowrider Navy Radioman Veteran Join Date: Jul 2007 Location: Western Kentucky Posts: 1,356	truck vapor locking?? Now that the weather has gotten warmer here, i've gotten the truck out for several short trips around town. Problem is, when it gets warm, say, 190-200 degrees setting in traffic, the engine starts to bog down when taking off. You can put the pedal half way down and no change. After a few minutes going down the road, it straightens up and power comes back. Does that sound like a vapor lock?? It's my '87 with the 454 in it, EDL 1705 carb and Air Gap intake. Thought it may be dirt in the carb but it doesn't happen all the time, just when the engine is heated up real good. Any thoughts??? Ken __________________ 1987 Chevrolet R10 Silverado BBC Build thread - SOLD 1986 GMC Sierra Classic - SOLD 1957 Chevy Step Side Daily Driver; 2005 Chevrolet Silverado 4x4 Z71 Stepside - SOLD 2005 Chevrolet Tahoe Z71

05-22-2009, 10:52 PM	#2
sdavid Registered User Join Date: Mar 2005 Location: Livingston, TX Posts: 56	Re: truck vapor locking?? I think a vapor lock would actually kill the engine. Or in a furd with a carb it will. Your fuel could be boiling inside the fuel line. Under hood air temp could be so hot it is smothering the engine. Check the fuel line to make sure it is not too close to the exhaust or other extremely hot parts. __________________ '81 C10 Stepside, SBC, T350, Wood Bed, and silverado options '87 K5 402 BBC, T350, 3.73s locked up, 2.5"Lift, 33x12.50x15s

05-23-2009, 10:03 AM	#3
LiveAnimals Registered User Join Date: Dec 2008 Location: Antelope, CA Posts: 681	Re: truck vapor locking?? here's something for both of ya, if the fuel is boiling that is the transition of liquid to a gas hence "VAPOR" lock. http://en.wikipedia.org/wiki/Vapor_lock __________________ Kameron YESTERDAY IS HISTORY - TOMORROW IS A MYSTERY I'm a Middle ClASS HOLE 07.5 Dodge 3500 CTD -- Daily 73 C10 Factory BB SWB 2WD

05-23-2009, 10:40 AM	#4
Nolowrider Senior Member Join Date: Jan 2005 Location: New Orleans Posts: 1,365	Re: truck vapor locking?? Like David said, def check your fuel line routing. Make sure it is not laying on the intake or anything else that really gets hot. Make sure you fuel line is not too close to the radiator outlet, down by the mech fuel pump. Check the choke. Make sure it is opening all the way up when hot. I have seen coils ground themselves out when they get hot. If you have an external coil, where is it mounted? I don't think it is vapor lock per say, but maybe fuel perculation. When the fuel gets hot the vapors take up more space, this sometimes overpowers the needle and seat, fuel dribble down in the carb and cause flooding. Last edited by Nolowrider; 05-23-2009 at 10:41 AM.

05-23-2009, 07:24 PM	#5
87Lowrider Navy Radioman Veteran Join Date: Jul 2007 Location: Western Kentucky Posts: 1,356	Re: truck vapor locking?? All very good information... Thank you! I'll work on it this weekend and check all that. I do know the fuel lines are close to the lower radiator outlet and the header tube for #8. So, I'm re-routing those things first. The Carb has no choke installed. It's a manual choke 1705 but not hooked up... Thought about buying the automatic choke for it and installing it. Local speed shop carries it. Kenny __________________ 1987 Chevrolet R10 Silverado BBC Build thread - SOLD 1986 GMC Sierra Classic - SOLD 1957 Chevy Step Side Daily Driver; 2005 Chevrolet Silverado 4x4 Z71 Stepside - SOLD 2005 Chevrolet Tahoe Z71

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