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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Cheyenne1010 on April 09, 2022, 07:17:22 AM

Title: Carburetor
Post by: Cheyenne1010 on April 09, 2022, 07:17:22 AM
Hey guys im Robert and i have a 1973 Chevy C10 long bed.what can i do to keep my truck from vapor locking thats not going to cost thousands of dollars.any help is very much appreciated.
Title: Re: Carburetor
Post by: LILT77 on April 09, 2022, 11:28:35 AM
Possibly look at a fuel vapor separator filter. Wix 33040. I know this has worked for some people. The offset nipple goes back to the tank
Title: Re: Carburetor
Post by: Rapid Roy on April 09, 2022, 12:19:32 PM
If you have a metal line from pump to carb, you can get pipe insulation at Lowes or Home Depot and wrap around it. I did this from engine to pump. It is the round foam like material. So far in the last 7 years I haven't had vapor lock.

Sample of what I used. There are different ID sizes. Some has tape on both sides of split to stick together.
You can also use zip ties if the tape does not hold. I prefer to use the black ties over the white.

https://www.lowes.com/pd/Frost-King-1-2-in-Wall-Thickness-x-1-2-in-Id-x-6-ft-Foam-Pipe-Insulation/1001277248
Title: Re: Carburetor
Post by: Cheyenne1010 on April 09, 2022, 04:14:11 PM
Thank you guys for the helpful information
Title: Re: Carburetor
Post by: VileZambonie on April 09, 2022, 07:20:36 PM
Are you trying to fix the symptom or the problem? These trucks do not have vapor lock issues unless someone did some butchery to cause it. Make sure the fuel tank is properly vented. If you loosen the gas cap and your vapor lock issue goes away, there's your first clue.
Title: Re: Carburetor
Post by: Big Dee on April 09, 2022, 07:49:06 PM
My engine would stop sometimes when hot. I had to change my fuel pump several times. ac delco solved the problem.
Check the return line also.
Title: Re: Carburetor
Post by: Cheyenne1010 on April 10, 2022, 07:37:08 AM
It would vapor lock on me with the mechanical fuel and its done it when i installed an electric fuel pump.fuel cap is new and venting properly and I've changed the fuel filter also.when i open the gas cap while its vapor lock nothing happens.there is no the only thing i haven't change is the charcoal canister.my fuel line runs along the frame then up the front of the engine then above the intake manifold to the carburetor.my fuel pump and gas tank only has 2 lines.1 from gas tank to pump and 1 gas tank to charcoal canister,so i have no return line.
Title: Re: Carburetor
Post by: JohnnyPopper on April 10, 2022, 01:33:17 PM
Had the same prob on my '73 3+3, it was my electric fuel pump was too close to the exhaust.

I could tell when VL was going to happen, the pump starts to get loud enough to hear when driving.

I used some sheet metal as a barrier.

All better... 8)

Title: Re: Carburetor
Post by: Cheyenne1010 on April 10, 2022, 03:39:40 PM
I think thats what i need to do because my electric fuel pump is kinda close to the exhaust pipe
Title: Re: Carburetor
Post by: VileZambonie on April 10, 2022, 06:16:58 PM
Unless you have an in tank fuel pump, your electric fuel pump may be the source of your issues. Make sure no fuel hoses are kinked as well. If you have a new fuel cap, is it vented or sealed? Vapor lock is when fuel boils in the fuel line. A pressure drop can cause the boiling point to drop and lead to potential vapor lock. Why do you think you have vapor lock anyway?
Title: Re: Carburetor
Post by: Cheyenne1010 on April 11, 2022, 04:18:00 AM
The reason I think it's vapor lock is because I'll be driving and my truck will turn off,it will restart for a few seconds then turn off again.i'll try again to restart and it just wont start.if i wait about 5 to 10 minutes it will start but 5 miles later it'll turn off again.this only happens when its hot outside.(90°-95°)
      I installed an electric fuel pump and i installed it exactly as the instructions said to do it and ran good for 2 years,then a few days ago it died on me,shot some starting fluid in the carburetor and it started,then 10 miles later it died again.by now its cooler outside and i had waited like 30-40 minutes without starting it.so i started it up and drove 35 miles  to my home without any problems
Title: Re: Carburetor
Post by: JohnnyPopper on April 11, 2022, 10:40:50 AM
Sounds like vapor lock, does your fuel pump get louder? As in clacky? If it's trying to pump vaporized gas it gets noisy.

In any case, it sounds heat related. Curious why for 2 years it was good?

Check for exhaust leaks that would blow hot gas on any part of your fuel delivery system.
Title: Re: Carburetor
Post by: Cheyenne1010 on April 11, 2022, 11:21:14 AM
i have notice what sounds like an exhaust leak and it sounds like its coming from the collector where the exhaust manifold and exhaust pipe meet.i need to check it out real quick
Title: Re: Carburetor
Post by: TexasRed on April 13, 2022, 07:02:07 PM
Can you go back to a mechanical fuel pump? You may look into adding a return line or a "vapour" or "vapor" line back to the tank. Electric pumps don't like to be dead headed. It helps both with vapour lock.

I'd make sure all your rubber lines are good and not cracked either and it's not trying to suck air instead of fuel.

Potentially could be an ignition issue too, but the starting fluid kind of points in a different direction.
Title: Re: Carburetor
Post by: Cheyenne1010 on April 24, 2022, 11:50:51 PM
It vapor lock on me again today and it wasnt even hot today.my sending unit only has 2 lines coming out of it,one line to the carburetor and the other to the charcoal canister.is it possible to change my sending unit to a 3 line and a mechanical fuel pump to a 3 line that way i can have a return line to the gas tank?
Title: Re: Carburetor
Post by: JohnnyPopper on April 26, 2022, 03:53:37 PM
Think this through with me.

It was good for two years, what changed?

Physically VL occurs when liquid gasoline changes it's nature to a gaseous state.

Your fuel pump can't pump gaseous gasoline. Only liquid.

The only things that makes it change state is heat, lots of it.

Find out where heat  is coming into contact with your fuel delivery system, metal and rubber lines, fuel pump, etc.

My money is on an exhaust leak.

Is there a reputable muffler shop that can find it for you?
Title: Re: Carburetor
Post by: Big Dee on April 27, 2022, 09:58:16 AM
If your truck didn't have a return line then so be it.
a good mechanical fuel pump is the way to go.
check the vent line by blowing air through it, both ends.
charcoal canisters don't last forever.
 ;)
Title: Re: Carburetor
Post by: peewee0413 on July 14, 2022, 07:30:25 PM
DEI has tons of heat shielding available. Very good at keeping vapor lock down, as well as protecting things you don't want burnt. (https://uploads.tapatalk-cdn.com/20220715/224dfa3eac5b05909f738ccd646977dc.jpg)

Sent from my SM-S908U using Tapatalk

Title: Re: Carburetor
Post by: Cheyenne1010 on December 16, 2022, 12:54:55 AM
My exhaust manifold was heating up the fuel line,so what I did was add a fuel return line and im happy to say no more vapor lock.with the return line fuel doesn't stay in the line long enough to heat up.
Title: Re: Carburetor
Post by: JohnnyPopper on December 17, 2022, 07:53:41 PM
Good to hear! Thanks for the update  ;)