The vapor lock problems I used to wrestle with back in the 80s and 90s involved the gasoline in the carburetor float bowls; not the lines.
As I mentioned previously, many of the Japanese carbs had sight glasses on the side of the float bowl where the fuel level could be determined visually in seconds. Shut an engine off on a hot day, wait a few minutes, and you could see the gasoline boiling like mad in the float bowl.
This in turn forced gasoline out of the carb and into the intake and also vaporized some of it through the float bowl vent.
In some cases it was bad enough the top of the carb could be removed and there would be little if any gasoline in the carb at all.
The Hitachi carburetors were horribly prone to this problem and Subaru issued about half a dozen “fixes” for this problem which sometimes helped but in most cases not that much.
Back in the day, some Toyotas were fitted with a small (roughly 2-3" diameter) fan that would blow air at the float bowl when the temp hit a certain mark in an attempt to hold float bowl boiling down.
Ok, thanks, that makes sense. The fuel in the carb bowl just boils and evaporates, leaving little to nothing left to start the engine. I suppose another adverse effect could happen too, if one of the fuel passages inside the carb had enough fuel vapors in it, that might prevent the venturi pressure difference from sucking the gas up and into the intake air stream.
If the fuel lines are all upward sloping to the carburetor vapor lock will be nearly non existant. The problem is the inverse of hair in a sink drain trap.
Twenty five or so years ago I had a Ford Granada with an inline 6 and during the summer it suffered vapor lock quite often.
I changed the steel fuel lines to rubber and made a 1/2" thick insulator block to fit between the carb and intake along with raising the float level a tiny bit.
Those mods seemed to cure it because the vapor lock issue never happened after that.
I do not think you need a new distributor and the coil is still last on my list. Since the car is hard to start after a half hour, that rules out the fuel pump and the fuel lines. Even if they had a problem, the fuel bowls would still be full of fuel so the car should start good and run for a minute or two before missing.
The empty fuel bowl in the filter also does not concern me either, they always seem to be full of air, yet gas still flows through them. I think the issue is in the carburetor but I can’t help you on this. I have worked on a lot of Carters, Rochesters and Webers, but no Holly’s.
Now last nite tore the whole trunk apart. Down to the top of the fuel tank. I have a Cougar book that shows every part of this car and of the mustang. On the cougar they are showing a vent along side the fill pipe on the tank. On the mustang I don’t see one, I’m telling you this because there is undoubtably no vent line on this fuel tank, maybe the po put a mustang tank in it? But that doesn’t really matter rite it’s not gonna help the vapor lock issues.
If this was my car I would disconnect the fuel line at the pump , the line that goes back to the tank . I would then use an air hose & blow back through the line & blow the push on strainer on the pick-up off . The strainer is in the picture Barkydog posted .
At some point in time there must have been a lot of junk coming through the fuel line for the po to have installed 3 fuel filters . It’s possible that strainer was in the old tank . If you haven’t already done so , I would also replace the 1 filter you have left .
The 351 I had didn’t have an inline filter between the pump & the carb . Mine still had the factory 4 barrel & it may have had the filter that fit in the carb . It’s been many years & there’s things I’m not positive of but mine had aftermarket headers , thrush mufflers , 4 speed manual & the fuel lines were completely stock & I never had a problem .
The Weber on it has 8867 stamped on the top but from what I read that is only the air horn number. Weber made carbs for edlebrock and the only other number on it is barely readable on the back and it is 06 so I’m guessing it could be a 1406 witch is a 600 cfm edlebrock. Across the front the sticker does say Fuel Force Proformance. So I replaced the fuel pump today And rerouted the fuel line again and blew out the fuel line the best I could. I don’t think there is any other way for this fuel line to run anymore. I drove around for a while in the middle of the day then stopped for a half hour. Before starting I looked at the fuel filter and there was still gas in it, that’s already better than it was. Then she did take a few times to start but I got her started. Ran down the road without stalling or hesitating witch is a Big plus but while sitting a a railroad crossing the Rams would drop wanting to stall but I was able to keep her running easily with a little pump of the gas. I think this could be something different than the problem we have been working on because I was able to start and drive home after letting it sit for a half hour. Tomorrow I will really know more as I do a usual day and see how she acts.
Bill Russe;= thanks for showing me how to delete a post. I was using Safari for a browser and the gear icon did not appear but when I use Firefox it does.
Ok so I just got back from lunch and again like yesterday she started after sitting for a bit but rougher than when cool and the first time I put her in drive she stalled but started rite back up I revved her a few more times n she took off. Now again at the last light be for work witch is a Long lite the rpms ussually are at 8-900 they would drop down the 500 shake the car n act like it was gonna stall but I never let her…that’s definitely happening only when it gets pretty dang hot. I’m thinking I need to do plugs, wires, cap n coil before I start trying to figure this one out only because the po told me a different story the other day than what he had told me in the beginning and they are older than I thought they were so it would be a good idea to replace them either way. What do you think about switching to a HEI distributor n coil I’m not looking to have a race car I’m looking for more of a nice 3out of 5 day daily car.
OK, instead of insulating the fuel lines, I would suggest that you insulate the headers. There is a header wrap for this that costs about $80 and I think it might solve several issues. It may even add some additional HP unless you have a cold air induction (CAI) system as the headers raise your underhood temps. If you have a stock type air cleaner, then the incoming air is hotter, reducing HP by as much as 5%.