old school mechanics, step inside

[GrayZ]

Hello, all, as many of you know, I'm not Mr. Goodwrench
(insert you're own pun here) but i do have a mystery
that i cannot seem to get fixed. Non zr-1 related.
I have a 1979 dodge motor home, i traded an old bassboat for, wifey and i fixed up the interior and we use it to tailgate at the Rams games;
and did i mention, it hates me. it will idle.
but once it gets a load, or warmed up, it coughs and sputters, then dies, after a few minutes, it will start and run again, for a short distance, then again, dies.
to date, this is what we've replaced.
fuel filter, mechanical fuel pump, carburetor, coil
the engine is a 360 v-8 the gas gauge does not work.
we have considered, the boot inside the fuel tank is clogged, one friend suggested it might be my key locking gas cap, causing some sort of negative pressure.
so.... any idea's boys or girls, i'm about ready to
start a bonfire. :icon_scra :mad:

[kenthompson]

Vapor lock

[GrayZ]

i thought vapor lock was a good thing :D
so....if it is indeed vapor lock, will a new gas cap
be the fix?

[kenthompson]

It's a motor home right?

And a mechanical pump?

The poor mechanical pump has to draw fuel all the way from the tank (at the rear?).

could you try an electric pump next to the tank to push fuel to the mechanical? (we don't need a BG400 here!)

Otherwise, watch out for heat soaking the fuel lines.

[RICHARD TILL]

is the carb a carter afb, a thermoquad or a holley? they all have the same bolt pattern and are used on that model motor. sometimes these carbs have a screen at the inlet that can get dirty/plugged. just when the motor stops take the breather off and work the throttle. check to see if the accelerator pump is pumping fuel. how old is the gas? have you pulled the coil wire to check the spark? a gas cap wont cause or prevent a vapor lock.

[GrayZ]

is the carb a carter afb, a thermoquad or a holley? they all have the same bolt pattern and are used on that model motor. sometimes these carbs have a screen at the inlet that can get dirty/plugged. just when the motor stops take the breather off and work the throttle. check to see if the accelerator pump is pumping fuel. how old is the gas? have you pulled the coil wire to check the spark? a gas cap wont cause or prevent a vapor lock.

i took the ramanator, to a shop.
the gas is not old, it has a new coil
we replaced the entire carb. with a new stock one.
as well as the mech. fuel pump and filters

[fred]

Points or electronic ignition? My guess is that it's heat related which points to a distributer problem (hey I made a punny!) On a Motorhome it's an outside chance, but you may want to check for a clogged cat/muffler. It's a little difficult, but check to see if there is fuel in the carb (accelerator pump/ dripping into the venturi's. . Quite possibly the ignition module. (I was a young man till I ran into Dodge motorhomes).

[GrayZ]

Points or electronic ignition? My guess is that it's heat related which points to a distributer problem (hey I made a punny!) On a Motorhome it's an outside chance, but you may want to check for a clogged cat/muffler. It's a little difficult, but check to see if there is fuel in the carb (accelerator pump/ dripping into the venturi's. . Quite possibly the ignition module. (I was a young man till I ran into Dodge motorhomes).

fred, the ignition module is it on the firewall?
i had another friend mention this possibility

[fred]

Yes, I think it is, don't forget about the pickup coil in the distributer.

[GrayZ]

http://i40.photobucket.com/albums/e243/sierragifts5/vodka.jpg

thanks for those that replied to the post, i will try you're home remedies

[gbrtng]

On a Motorhome it's an outside chance, but you may want to check for a clogged cat/muffler.
Sounds suspiciously like a clogged exhaust to me too. Pull the pipes at the manifolds and run it open. Else find a pressure gauge and tap into the front pipe(s).

[cuisinartvette]

Another vote for vaporlock.

does the motorhome have the Lean burn system still on it? If so junk that crap and go aftermarket. The modules on those things arent the best .

[WydGlydJim]

It needs to be hooked up to a scope while presenting the problem. If it is the ignition module, it will be evident by the scope pattern. If you feel it is fuel, then you should be able to keep it running by squirting some carb cleaner into the throat of the carb, while it is presenting the problem, and it should correct somewhat and run while the scope pattern should remain normal. I have seen the sock in the tank also collapse, then relax, collapse, then relax, etc........

[GrayZ]

i spoke with a local old school mechanic today
he told me the coil inside the distributor
is probably my problem, he also said if that did not
fix it, that, it my be a timing chain as it backfires
a little through the carb, when it' starts to die.
thanks everyone for the great advice. i'm gona leave
no leaf unturned. got to get her ready for football season. :D