'92 Coachman Chugs & Stalls Cold Gas to Fix - Another Way?

[Leahbyers78]

1992 Coachman Class C

After 3 hours the camper starts to chug and stall. When it hits its breaking point it will just stop. If you put cold gas in the tank, it starts right up. No problems if you travel during cooler weather. We have brought it to shops but most don't know how to work on that year of an RV.

Suggestions on how to repair?

[ron_dittmer]

Stim wrote:
When it acts up stop and open gas cap and listen for vacuum sound.
Might be a problem with fuel vent system (emissions). ??

Yes, this came to my mind.....negative pressure inside the fuel tank.

When it happens again, take off the gas cap to neutralize the pressure in the tank, put it back on, and see if the problem can be repeated with the same band-aid solution.

[Gjac]

Leah how are you making out with your problem?

[Stim]

When it acts up stop and open gas cap and listen for vacuum sound.
Might be a problem with fuel vent system (emissions). ??

[Gjac]

To test for a dying fuel pump, the next time it shuts off and wont start spray some gas or starter fluid in the carb if it starts and keeps running while you are pumping gas in but engine dies when you stop its your fuel pump. To test for a failing coil check spark when engine is cold then check spark when engine is hot and shuts down. Will the spark jump .250 to ground? My guess is a failing fuel pump.

[carringb]

SMPLMN, that does not quite match what I've seen when the fuel pump start running hot. I do think that if yours is original, it should be replaced. But I'd be suspect of the ignition coil in your case, due to the pattern/timing of your symptoms and because it idles even after your symptoms start. If your plugs have too much gap, that can also make the ignition coil run hot, and when it gets hot resistance increases and spark gets weaker.

[SMPLMN]

I have been having a very similar problem with a 96 Gulf Stream. 460 Engine. After running just fine down the highway for 45 minutes or so it will begin acting like a vapor lock when accelerating into a hill, Losing power etc. It never actually dies. When I pull over it will still Idle. If I shut off the engine even for a few seconds, I can go again for a short ways. The longer I drive, the more frequently this happens.
My mechanic is mystified, as the fuel pressure is good. All his diagnostics say fuel pump is fine, but he never got it to act up.
Sounds like I am experiencing the weak/dying fuel pump issue?

[A_Good_Cigar]

Weak/dying fuel pump! EFI 460's are NOTORIOUS for this problem, not a matter of if, but when the original pump fails! Vapor lock next to impossible, fuel injection operates at too high a pressure for that. Depending on your tank size (35 gal?)you may be able to do what some have done on Class A's with 460's, and always run the fuel tank on the upper half of the gauge, so the fuel doesn't get the chance to heat up too much. Regardless, plan on replacing the pump sooner rather than later. If having a shop do the replacement, be sure and have them clean out the tank! Good luck

[carringb]

Its the fuel pump. BTDT.

That generation Ford had pump impellers that swell with age when using E10 gas. That makes it run hot which causes vapor lock inside the pump. This is why cool weather or topping off with cold gas fixes it.

The newer Ford pumps will fit, and either Ford or the parts counter should include a wiring adapter to use the new pump.

[Hank85713]

upgrade your ignition system with high out put coil and wires, may even need to go to a colder plug it will improve so much. Did this on my 89 F250 with an MSD ignition.

https://www.google.com/search?client=firefox-b-1-d&q=ignition+system+upgrades

yes there is a possibility of in tank fuel pump issue??

[midnightsadie]

a coil will do this gets hot shuts down cools off goes again. has nothing to do with gas, try it .

[midnightsadie]

weak fuel pump.water in the gas. coils get hot and shut down vapor lock.