47-55.1 vapor lock issues

[jeffbcn]

I'm at my Wit's End trying to figure this out I have a 1947 thriftmaster with a 235 from 1962 and it has some serious vapor lock issues.
I have a new carburetor a new Edelbrock electric fuel pump as well as a new mechanical fuel pump and I continue to have these problems I thought that it might have been the heat Riser stuck and so I had the heat Riser completely removed and I'm still having the issues I'm at my Wit's End and would appreciate any ideas.

[mongocanfly]

your exhaust and fuel lines are on opposite sides of the truck...what about your gas cap...is it venting..when it locks up try cracking the cap and see if you hear air rush in

[jeffbcn]

It vapor lock even with a cap off.

[mongocanfly]

what about the fuel pump...is it overheating?...can you tell from feeling the fuel line if it feels hot enough to vaporize gas?

[mongocanfly]

also why 2 pumps?...one should be enough

[jeffbcn]

I have a handheld infrared thermometer the electric fuel pump was at about a hundred and forty the mechanical fuel pump was at a at about 200 the fuel lines about 170 the carburetor about 190 the intake manifold 220 the exhaust manifold about 350.
I had the electric added because this problem has been chronic and I've been through about four or five mechanical fuel pumps in the last three and a half years or about 9,000 miles.
.

[jeffbcn]

I also have a metal inline fuel filter and that was almost 200 degrees

[popstand]

vapor lock? Are you serious? I haven't heard of vapor lock since the 50's.

2 fuel pumps? Why?

[mongocanfly]

may try bypassing the mech pump...is the electric pump close to the tank? a 6cyl shouldn't need duel fuel pumps

[mongocanfly]

heres a pretty good read....https://www.onallcylinders.com/2015/...ou-can-fix-it/
where is your filter located?
you might try some heat shield insulation on the fuel lines
id also look at the tank...make sure there are no restrictions there on the pickup tube...it could just be starving out

[nvrdone]

if you still have the electric pump in place, id hook up a pressure gage to the out let side and see what kind of pressure you have. if the pressure is low, that would indicate some kind of blockage in the tank pick up. that could be causing the fuel to get hot and vaporize.

[Ironworking]

Some of the best heat shield on the planet is 1/4 cork. I buy 12" squares of it off the Big Bay an it works like a charm even at 400 degrees.

[Jemezcrusher]

Originally Posted by mongocanfly

heres a pretty good read....https://www.onallcylinders.com/2015/...ou-can-fix-it/
where is your filter located?
you might try some heat shield insulation on the fuel lines
id also look at the tank...make sure there are no restrictions there on the pickup tube...it could just be starving out

Be careful with insulation. It can hold heat in rather than letting the steel or aluminum fuel line dissipate the heat

[dsraven]

I would suggest to start at the tank and work forward. completely drain it into a clean container and see how the fuel looks. check the flow as you do that, with the fuel cap on for the first little bit, to see if it is allowing the vacuum in the tank to relieve. when done remove the outlet fitting and the hose and see how that looks. some had a shut off valve there so also check that if applicable. remove the sending unit and look inside or use an inspection camera and look down inside the tank for any foreign material in there that could possibly slow down the delivery process. you never know what could be in there after all these years. when all good assemble that with a new outlet hose and then follow the steel line forward from there. looking for pinched areas or rusted areas that could be swelled on the inside of the line. check the fuel delivery from the electric pump as you go, pressure and flow. same for the mechanical pump. follow it right up to the carb. even pull the lid off the carb and see what you find. you just never know but there are lots of these trucks driving around with a 6 cyl engine and not too many have to use 2 pumps to deliver enough gas. gotta be aflow issue someplace if the fuel system is basically stock except for the elec pump.

[jeffbcn]

Thank you for your very detailed reply it makes a lot of sense to do the investigation thoroughly unfortunately I don't have the financial resources to go that far that fast nor am I physically capable anymore of doing it myself so I have to take this a little bit at a time.
so far what I have done is is noticed that the electric fuel pump that I have doesn't seem to be working at all .It may be because my mechanic mounted it against the block for a while and I could have fried it so I purchased another Edelbrock 1703 I think it is it's the 2 to 3 and 1/2 PSI fuel pump and I'm going to mount that by the tank my son-in-law is going to help me and get rid of the mechanical fuel pump and put in a new fuel line from the fuel pump up to the carburetor with a shielded fuel line and I'm going to start with that and see what that does I think that once I do that and if it continues to vapor lock then I think that it's got to be the tank so then I'll work on that.

[geezer#99]

In your other thread I said you don’t have a fuel delivery problem or a vapor lock problem.
You’ve got a cooling problem. You described your cooling in post #11. All is well until you get into slower traffic.
Putting on a new pump and lines will only empty your wallet. You won’t gain anything. You’ve already got a system that works. Remove the electric pump though. It’s not needed.
You need to get a handle on your cooling problem. Install a fan shroud with a correctly spaced fan is what is needed.

There’s a link in your other thread for shroud’s.

I’ll link it here again.

https://www.speedwaymotors.com/shop/...m_content=Shop

[jeffbcn]

Thank you for the reminder again about the cooling problem yes I know I do have one. I have a fan spacer I just need to install it and that will bring the fan about 1 inch or so away from the radiator I was hoping that that would cure the problem at idle or slow speeds if not I'll have to get a fan shroud I haven't seen anything I like the only thing I've really seen is that plastic one that you cut out yourself . is there something else? Also I was thinking about going back to the stock fan I put a 6 bladed Flex fan hoping to cure the problem I while back but when I really look at the flex fan and my stock fan it looks like the four bladed stock fan has a lot more surface area than even the six blade has and I'm wondering if that will actually push more air.

[geezer#99]

Moving the fan closer won’t change the need for a shroud. There are no pretty factory ones. None made from plastic in that link. They’re aluminum.
You might be surprised at how much better your 4 blade works compared to a flex fan.
I’d recommend measuring your stock or flex fan for size and then find a 6 blade to fit that you can fit a shroud to.
So go measure your fan and let us know and we’ll find you a 6 blade.

[dsraven]

yup, like geezer says, get it ALL right. check the condition of the tune, valve lashes etc, all that. a lean mixture will run hot.
check exhaust system for signs of back pressure, loose baffle inside the muffler etc
look at the cooling system, including thermostat, hoses, fan and shroud etc. even the coolant. check the strength because some guys will run just water thinking they are saving a couple buck but coolant is not just antifreeze, it is an anti corrosion, lubricant for the water pump and also raises the boiling point. check out front to ensure the rad can actually pass air through it. also check inside the rad looking for a blossoming at the ends of the coolant tubes. this would indicate some build up in the tubes which reduces capacity to cool significantly and would suggest that the inside of the engine is the same. a bit of rust or corrosion build up goes a long way in allowing the engine to cool properly.