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Honestly that is something I am thinking about, in terms of switching to an electric pump.
You don’t need an electric fuel pump, with the lines wrapped in heat shielding and the “vapor separator” swapped for a one in one out fuel filter you should be fine. You’re trying to use a complex solution to fix a relatively simple problem.
 

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Honestly that is something I am thinking about, in terms of switching to an electric pump. I’m only sending fuel back to the tank due to the heat issue, the fuel was getting hot and vaporizing in the clear fuel filter, starving the carb of fuel. Hence adding on the extra filter/separator.
I now have all of the rubber lines wrapped with a heat shield tape. The excessive heat I think was mainly due to the timing issue, it was running hotter than I expected
2 vehicles Ford built that come to mind that had vapor lock issues from the factory. 67 Cougar 70/71 Torino Cobra. Both had 5/16" fuel supply to the pump. 68 Cougar got a 3/8" line problem solved. Torino Cobra just went out of production, but anyone that still had one switched to the 3/8" line the the 429 SCJs had.
Personally that heat tape in the engine compartment is useless. Maybe on the out side lines. Use some that is tried and proven. And with a mechanical pump the pump itself is hot.
 

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1977 F100 - 460 from a 1969 Lincoln, C6 Trans, 9" Rear
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Discussion Starter · #43 ·
Hey Tim, that was the issue I was having - vapor locking. The fuel would overheat and vaporize, so that’s why I installed the extra filter with the bypass. I’m stuck toying with it trying to determine if I need the bypass filter or not at this point, since I’ve wrapped up all of the rubber lines near hot points.
 

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Discussion Starter · #44 ·
2 vehicles Ford built that come to mind that had vapor lock issues from the factory. 67 Cougar 70/71 Torino Cobra. Both had 5/16" fuel supply to the pump. 68 Cougar got a 3/8" line problem solved. Torino Cobra just went out of production, but anyone that still had one switched to the 3/8" line the the 429 SCJs had.
Personally that heat tape in the engine compartment is useless. Maybe on the out side lines. Use some that is tried and proven. And with a mechanical pump the pump itself is hot.
Thanks! The picture posted, it appears you’ve got a robust heat wrap around your fuel line. Looks a bit cleaner than my setup, and as someone before mentioned, air is the best insulator. I might have to try that out sometime if the fuel/heat issue persists.

I definitely should also mention to others reading and responding - the fuel heating issue isn’t being helped by the fact that the truck is just idling in the driveway, and that the timing was off (causing heat buildup). Didn’t seem to notice the fuel vapor issue once driving around the neighborhood. I’m working on getting a few things dialed in and can’t legally drive out on the road with it yet, so that’s kind of the problem, too.
Right now, I’m in a holding pattern until I can go get some more fuel for the truck. Once it’s refilled I’m going to tinker some more. Need to resolve a backfire that’s occurring in the intake.
 

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Hi
as you have stated that with the by pass filter your glass filter is NOT filling up..SOOO you are NOT getting the amount of fuel your carb or motor needs and NOT filling up the fuel bowl.. there for getting a LEAN pop at the intake... dump the by pass filter and get a regular one in one out filter and figure out where you are getting the vapor lock from and FIX that. You are only creating more problems..

good luck take care be safe
tim
 

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Discussion Starter · #46 ·
Hi
as you have stated that with the by pass filter your glass filter is NOT filling up..SOOO you are NOT getting the amount of fuel your carb or motor needs and NOT filling up the fuel bowl.. there for getting a LEAN pop at the intake... dump the by pass filter and get a regular one in one out filter and figure out where you are getting the vapor lock from and FIX that. You are only creating more problems..

good luck take care be safe
tim
Went and filled up a couple gas cans to refill the truck for now (not yet street legal so I can't take it to the gas station). I think what I'm going to do as a test for now is pinch off the return line and let the truck idle and see if the clear filter runs low on fuel/vaporizes again like it did before. I think other than the steel lines, I've got everything wrapped for heat protection. If it runs fine then I'll ditch the return filter. Hoping that cures the intake pop. Thought it would be a timing issue but I've adjusted it down now, to 15 BTDC with no vacuum advance. Seems to have cut down on the excess heat under the hood, too. Fingers crossed, I'll report back here once I get some results.
 

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Went and filled up a couple gas cans to refill the truck for now (not yet street legal so I can't take it to the gas station). I think what I'm going to do as a test for now is pinch off the return line and let the truck idle and see if the clear filter runs low on fuel/vaporizes again like it did before. I think other than the steel lines, I've got everything wrapped for heat protection. If it runs fine then I'll ditch the return filter. Hoping that cures the intake pop. Thought it would be a timing issue but I've adjusted it down now, to 15 BTDC with no vacuum advance. Seems to have cut down on the excess heat under the hood, too. Fingers crossed, I'll report back here once I get some results.
Still don't understand why the return line on a stock type, mech diaphram pump. Unless you have a high volumn/pressure pump, mech or electric, you don't need it. It bleeds of the fuels PSI and volumn by providing a easier path for it to flow all the time.
Yeah at idle your carb needs very little fuel and what isn't sent back to the tank bleeds into the carb. When the carb/eng needs the more fuel flow, it's not there due to the bypass.
 

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Discussion Starter · #48 ·
dacofa, I agree with you. It makes logical sense, I am just trying it because the fuel would get too hot while idling in the driveway, and the clear filter would have nothing in it other than vapor pressure. Totally understand that it’s not really fixing the issue, but I’m still trying to find where the fuel is getting too hot. At this point, the only hot spot would be the pump itself. Hopefully going to play around with pinching off the return line today and seeing how everything works. Thinking the timing was too advanced and got the engine temps hotter than they should be. Also understand idling in the driveway isn’t providing any air flow, either.
 

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HI........ MAN ... BACK in your Post number #13 and post #25 you already tried the pinching off the return line and YOU said the pressure stabilized. WHY ARE YOU GOING TO TRY IT AGAIN..... JUST DUMP THAT FILTER AS IT IS NOT FACTORY AND IS ONLY CREATING MORE PROBLEMS AS IN LOW TO NO FUEL IN THE CARB BOWL AND MAKING IT HAVE A LEAN POP OR BACK FIRE AND NO POWER ABOVE AN IDLE... GET RID OF IT AND FIND THE REAL PROBLEM...
Put a timing light on it. adjust air/fuel mixture screw and idle screw.

take care
tim
 

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Discussion Starter · #51 ·
I wouldn’t say I’m not listening or learning… just trying to solve the problem.
the previous posts where I mentioned that I pinched the return line, was literally me pinching with fingers for a few seconds.
today, used needle nose grips and locked it down and ran the truck… and for the 15 or so minutes of running it in the driveway, I didn’t notice an issue.
Trust me when I say, I truly appreciate the advice given. I’ve only ever worked on EFI and modern engines, carbureted engines aren’t super different, but it’s a learning curve for sure. Especially with a truck/engine where I have next to no back history,
I’m figuring it out as I go.
All that said, I’m thinking that filter is going bye bye tomorrow. Thanks everyone, again, for your help!
 

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Discussion Starter · #52 ·
On another note - last weekend, I dialed back the timing to 15*, and today, couldn’t get the truck to start at all (would try but not fully go, would backfire and start a fire in the carb). Put the timing back to where it was originally (about 24*). Started up and idled okay. Seems to still pop in the intake when throttling up while parked. Fuel bowls are staying level, plenty of fuel pressure. What’s the next step? Pull valve covers and check for loose components in the valvetrain? Something else?
 

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Sorry..
did you unhook the vacuum advance and plug it going to the carb, when you did the timing??
Good luck take care be safe
tim
 

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Discussion Starter · #54 ·
Sorry..
did you unhook the vacuum advance and plug it going to the carb, when you did the timing??
Good luck take care be safe
tim
Sure did! I didn’t check it after reinstalling the advance, since I ran out of fuel at that time. may try richening the fuel mixture some more to see if that helps with the carb/intake pop
 

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HI Vacuum advance does not effect setting timing at idle..as it is unplugged.
Carb mixture screws should be like 1 1/2 turns out each from gently bottomed out, to get it started.. the adjust them (after warm up) with idle at 650 rpm's for a manuel and 750 rpm's for an automatic.. turn them in/out evenly each while adjust the idle after each adjustment to keep it at the set point. You want the smoothest idle with the mixture screws.. not to fat or lean.. a little goes a long way with the mixture screws start with 1/8 to a 1/4 turn..
You have to keep fuel in the tank or you are going to start having running and setting problems like you are having again.....

good luck take care be safe
tim
 

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Discussion Starter · #57 ·
I’ll definitely look into double checking the dampener/timing further. My uncle also mentioned that was a possibility of being off.

I ditched the fuel return filter and just ran the fuel line from the pump to the clear Wix filter and then to the carb. After 10-15 minutes of running, the low fuel problem in the Wix filter came back, but instead of rushing to shut the truck off, I waited to see if it would do it on its own. Go figure, I assume enough fuel pushed through and cooled off any vapor, and the filter began to refill. The engine never sputtered or lost power. It continued to do it during my crushing around the neighborhood and for another 30 minutes of idling in the driveway.

My question now is, should I just replace the steel fuel line with a 3/8” fuel hose and wrap it with heat protection in the area where it’s going to get the most heat (close to the headers)?

im also still experiencing the spark knock when under moderate to heavy acceleration. Compression checked out fine, 1-2-5-6 plugs were tan, 3-4-7-8 were darker and #8 seemed to be fouled (oily). No vacuum leaks that I could find the old fashioned way. Not sure if it’s a timing issue, spark plug issue, or fuel octane (currently running BP 93 octane).
 

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Discussion Starter · #58 ·
Glove Automotive tire Hood Automotive lighting Motor vehicle
Filter would refill back to this level after emptying itself.
Motor vehicle Automotive tire Automotive lighting Rim Gauge
Fuel pressure at idle with fuel getting hot. Normally at 6psi, reading about 3psi here.
Glove Sleeve Camouflage Headgear Military camouflage
Fuel filter would get this low for a minute, engine would still run and rev up.
 

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Don't replace it with a rubber hose. Worst thing you could do. If you're going to replace it, #6 braided steel line and use the insulation sleeves. Like the one I used in my picture. They slip over the fuel line and protect and insulate it. I use an electric pump at the tank with a bleed off line since the pump's rated flow is so high. The brass tee actually has a restricter plug in it drilled to 1/16" dia. I even use heat sleeves on my oil/trans cooler lines.
The fuel tank is also coated with heat shielding paint.
 

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HI
spark knock is timing.. re-set timing to a little lower 10 or 12 degs. with vacuum off and plugged, NOT 15* ... If it does not run at 10 or 12* you have problems with timing or distributor. or the damnpner is OFF..(slipped)

good luck take care be safe
tim
 
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