So here is the set-up that is going to eliminate Nose from ever having vapor lock again. This along with removing the filter in the Quadra jet and putting an inline in its place, so it does not need to be changed every 300 or so miles.

To Quote Professor Steve,,, drive Nose, put gas in it drive Nose some more!!!

This pump puts out 7 to 9 PSI, this is a bit more than the carburetor spec but the manual fuel pump is still in the system and it does recirculate, so my hope is that will temper the higher pressure.

If the manual fuel pump ever needs to be removed, a pressure regulator can be installed.

That looks impressive and expensive!

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What kind is it? You going to keep it a secret and charge big bucks to tell us or share your find with the world?

Steve really started this set up, Summit racing cannister fuel filter and a Holley Stealth fuel pump. Not too expensive about $150 including brass fittings.

On my nose I shielded the gas line from any heat sources, put in line filters and a 7 pound in-line pump, a new mechanical pump, rebuilt the Q-Jet and did everything else anybody threw at me, and when I sold it 15 years and more hours than I want to think about later, it still had vapor lock. I'm so glad I don't have this issue with the 78.

The GM fuel system is a good example of reverse engineering on the fly.

Bottom line: when fuel sits in a hot place it will vaporize. Unlike cars, the motorhome has a ton of heat generated up front that must run below and way out the back. Coupled with long dual exhausts, the entire bottom of the coach is a hot place....

Meanwhile we run steel lines along the frame next to the pipes, up to the lower front of the engine to a metal pump attached to the engine, at about 180 degrees. From the metal pump we run a metal line up the front of the engine between engine and radiator. Finally, we sit the carburetor right on top of the hot manifold. All with marginal filters. It's a wonder it ever ran when hot at all...

They made two changes to correct some issues. They put a rear pump inline to put pressure on the system from there forward. Later they installed the pumps right in the tank. (In my mind a step backwards since the filter and pump are inaccessible. I had problems with both my tank pump and the sock filter on it.)

They installed a line to recirculate the fuel from tank through engine pump back to the tank. A big improvement since the fuel in those lines was now flowing constantly and stayed cooler.

Sadly, that still leaves the engine fuel pump, forward line, and carb on a dead end in the hottest place in the coach. After I shut the engine down, the carb would always be empty the next time I started up, from the engine heat. (That's why I put in a switch on the rear pump to prime before starting.)

I ultimately abandoned the in tank pumps and filters. A straight suction line from the tank to a large filter and a rear pump, as Duane has done.

I never completely addressed the problem with the carb. When I converted to throttle body injection, the throttle body had ports for fuel in and out. It used a 20 lb pump in the rear. I abandoned the engine pump and ran directly to the throttle body. It has an internal regulator set at 13 psi. The fuel returned directly from there. This eliminated all the fuel lines around the engine also. The fuel was recirculating all the way from tank to throttle body, avoiding the engine bay. I never had vapor lock again.

If I still had the gasser I would work on eliminating the engine pump and metal lines. Run the pressure line from the rear filter and pump to the back of the engine, near the carb. Install a fuel pressure regulator there, one with a recirculating port. From there the return line goes back to the tank. In the short section between the regulator and carb I would install a transparent final fuel filter and eliminate the puny filter in the carb. That way there would be cool fuel circulating almost all the way to the carb, plenty of pressure and large serviceable filters.

Another modification may be helpful. The air filter housing on most has a horn to connect to a cool air intake duct. Many old coaches have no duct attached. I ran a flex hose from the carb out to the front where it got cool air.

Without the duct the carb is breathing hot engine bay air, when connected the carb gets cooler air, even when idling in traffic... (Cooler air is more dense and gives more engine power too.)

Good luck...

Short dark days, cold and snow... leaving for Florida on Saturday. I am ready!

DannyZ what do you see as the difference between your 78 and your Glasnose? The 88 had a 1/2 fuel line and the rear routing was mostly outside the frame, but other than that routing was similar to Nose. Did not have vapor lock in it.

As Steve outlined, rerouting the recirculation line to in front of the Carburetor, controlled by a primer button. We thought before the steel line running up the front of the front of engine might be a major problem.

Vapor lock seems to happen right after Nose is refueled, and on the road after a stop or slow down from hi-way speed. So keeping the fuel flowing might be the key.