Vapor lock.....

[artpeck]

Let me describe the routing and I will post ASAP. Up from the mechanical fuel pump to a filter on the top of the fire wall. Back down through a clip on the center nut on the valve cover and from there a right angle and another right angle straight to the carb at the height of the carb intake. Essentially parallel to the ground. At least 8-9 inches above the exhaust manifold.

[ybt502r]

For what it's worth - I live in Colorado and have a SIII at 8800 ft. It's pretty stock (mechanical fuel pump), and I've not had vapor lock issues. The fuel line routing is as per the book - it goes from the pump, along side the engine, over the front of the block near the thermostat, and then back to the carb (it's a rebuilt Zenith). I've added an inline filter over the years, but that's about it.

Don't know whether to be concerned or no, but she runs, so I don't get too fussed. There's enough else to keep me busy of course.

[daveb]

yeah, after 72 they started using those fuel filters on the firewall. Never owned one with that setup but have it heard it is not great.

Let me describe the routing and I will post ASAP. Up from the mechanical fuel pump to a filter on the top of the fire wall. Back down through a clip on the center nut on the valve cover and from there a right angle and another right angle straight to the carb at the height of the carb intake. Essentially parallel to the ground. At least 8-9 inches above the exhaust manifold.

[knac1234]

Sounds like stock routing is different based upon years, even for S3s.

From this thread:

daveB routes his in front of the valve cover and thermostat housing

artpeck has his from the firewall to the center nut on the valve cover

ybt502r with a later S3 has his on the side of the engine over the block near the thermostat

At this point the only conclusion is that none of these match mine, which then DEFINITELY must not be stock as it is slung over the valve cover to the carb with a zip tie on the carb intake hose!

At some point here I will need to play around a little!

Cheers,
Julian

[artpeck]

Definitely not stock. I know mine is at least for this year as the po was the only owner and did nothing to change the truck. I had a long time LR mechanic from the dealer where it was bought look over the truck and his assessment was that is was the most unmolested stick truck of it's vintage he had ever seen. Even the original tires that it rolled off the ship with. (yes those will be replaced as I work my way though things).

My routing includes the firewall blue bucket filter and an inline filter just below that.

Just a thought. Have you also checked your filters? A clog could be the thing that puts the truck over the edge.