At the risk of boring everybody, try replacing the coil, or the complete distributor including the coil. Even if it’s not the problem, it is good preventive maintenance.

The solution to fuel lock (vapor lock) is a continuous flow of fuel from
the tank to the engine and back again. The carburetor uses what
it needs and any excess is returned to the tank by a separate line.

This keeps a steady flow of cool fuel to the carburetor. It also cools
the lines and the mechanical fuel pump. Newer Chevy 454's used
it. My '86 345 has such a system.

I believe that you can get kits to retro-fit continuous flow systems.

87 Mh died
 

Wow, that does sound familiar. Both recent issues were not overly hot (80 degrees perhaps both days)

1987 325 Mh died on the road....help !
 

Thank you for all the amazing responses.
Mechanic and I are at a loss on on a firm diagnosis.
We have ordered another distributor to see how it reacts when installled. Says he can return it after testing.
I am installing a new ground wire as well.
Without the benefit of gauges to tell what is occuring when the failure happens, very difficult to diagnose.
My next trip will be my first in retirement and will only be 45 minutes to Wheatley Provincial Park at the end of May.

Again I will travel with trepidation, not a great feeling.
Thanks again for all the great posts, all have been taken to heart

1987 325 MH died
 

Is the system on your 86' aftermarket?
Do you know the name/kit name of the retro-fit?

1987 325 Mh died
 

Yes, replaced 2 years ago, chasing this issue

On my '86 the system is part of the mechanical fuel pump.
The pump has an input from the tank, an output to the carburetor
and a bypass that goes back to the tank. Since you have
a 454 you should be able to get the newer pump with the
bypass. You will need to run a separate line back to the
tank. My 345 also has the electric pump back near the
gas tank.

I don't know of a retro-fit kit. I do have vague memories
of such kits being sold 40 years ago.

Modern fuel injected cars have a fuel pressure control valve (fpcv)
but they are much higher pressure and are electronically controlled.
That is what would be needed but at a pressure of 6 - 8 PSI and
purely mechanical.

I am confused my 75' 454, argosy had a return line from the fuel pump back to the tank, why would a more resent model not have the same or better? I think My vapor lock problem was In the pickup line before the pump. Therefore i installed the in-tank pump.

To be on the safe side, with thoes long,wide, shallow rear gas tanks when travelling I'd keep well over 1/4 full no less, particularly if your heading into long slow hilly terrain.
To understand this problem take a flat oven roasting tray with some water in and now carry it about, that sloshing around exposes the mid gas tank pick up to sucking air.
There is a major problem!
Airstream's designers who were not automotive engineers retro fitted that P30 light commercial chasis and fitted that large flat tank in error.
Not saying its the only problem that can cause backfireing and power loss when it leans out from reduced fuel /air pockets but a safe bet is to keep the tank as full as you can to reduce your stress levells!
Happy Travells

Take a gander at proper truck fuel tanks they are narrow and deep and short, unlike our's.
Fill Up.
Gas dosn't last long if parked up long term!

Rus

The normal vapor lock situation is caused by the gas boiling in the
lines because of engine heat. The continuous flow systems are a
great solution to that problem. However vapor lock is not the
only thing that can cause fuel starvation.

There is a long line from the tank to the carburetor. Most AS's
have an electric fuel pump back by the tank. If that is not working
there can be a problem. My AS has a spin on fuel filter back there.
That could cause a problem if plugged up. There may be an in-line
type fuel filter someplace. My AS has a place for one but it is
bypassed. There is a fuel filter in the carburetor in the fitting
where the fuel pipe connects to the carb.

There are lots of things that can restrict fuel flow beyond vapor
lock. To really know for sure you need to fit a fuel pressure
gauge right at the carburetor and drive around.

Because of all of the discussion of fuel starvation issues I have been
thinking of installing one of these:
https://www.jegs.com/i/Holley/510/26-503/10002/-1

It is a pressure gauge system that measures up to 15 PSI.
It is also electric. The mechanical gauges will necessarily
have gasoline flowing in a hose behind your dashboard.
Does not sound good to me.

Has anyone installed a fuel pressure gauge?

Yes. The gauge at the lower right end.

Attachment 381297

Is that a 100PSI gauge? Do you have a fuel injected engine?

Yes, 100 psi Maxtow gauge.

And yes, it's fuel injected. Runs at around 28 psi.

that is some sick dash :rolleyes: and all that for just 20'

Well, if you can't impress them with length then you have to try and dazzle them with style.... ;)

1987 325 MH died, help
 

Thanks again fellow club members.

After a month at the shop and much consideration I brought the rig home today. The mechanic suggested replacing the distributor and see how it runs. He wanted me to take it out on several runs and see if there was a difference. I basically ran the same as with my old in static state so I opted to pull it out and have him send it back ( as opposed to me having to return and endure the cost of a reinstall of my old one which is only two years old) .

We did find that the actuator on the fuel pump had worked itself free of the pin that it pivots on so a new fuel pump was installed. He also noted that the line off my gas tank is larger than the one going to the engine (tank has been replaced) I did not see that as being an issue as I am only roaming the flatlands of south-western Ontario.

I'm standing by the fact that there is a bad ground, broken wire, bad connection or something of that nature. I'm blowing fuses for no reason, so that is the clue. I don't have currently have lost ads light, my running lights don't work and my generator will not Betsy lit. I'm going with I'm going to go through it myself or hire an automotive electrician.

Onward and upward, time to winterize it. Should be my first retirement project in 2021. All the best to y'all, safe safe. Happy camping as it is the best activity in these covid times, I don't see it going away anytime soon.
Chris