Rv falls on its face after engine is warm

[Rvnoobguy]

Hi there, I have a 1984 Fleetwood Southwind Rv. It has a 454 big block and I'm having a issue I can't seem to figure out. The rv starts up every time and idles perfect. It drives perfect while cold getting up to speed with no issues as well as going up hills with plenty of power. Once it has warmed up though if I slow down or stop and attempt to accelerate again, I have to lightly push the pedal or it will completely fall on its face losing all power.. If I attempt to go over 30-40mph after being warmed up it just falls on its face. Odd thing is, if I just keep driving it from the time I start it up cold without falling below 55-60 it will maintain speed but, the second I have to slow down for any reason it's all over. I have had the carburetor freshly rebuilt, no vacuum leaks and cats aren't clogged.. tomorrow I plan to try distributor and potentially the fuel pump... Anyone ever deal with this or have any suggestions ? Any input would be immensely appreciated..

[George_Beggs]

Back in the 70's GM put a brass fuel filter in the carburetor that the fuel line connected to. The engine would start right up; but then when I tried to accelerate it would bough down sometimes stop. Replacing the brass filter fixed it.

[stripit]

When I had a boat with 2 454's in it one engine ran perfectly the other stumbled and lacked power. So we figured fuel, checked everything and could not get the odd one to pull like the good one. One of the guys said lets put new plug wires on it, seemed like a waste to me but that was it. Never had backfiring, sputter or anything other than lack of power. So once that fixed it i also replaced the other motors wires, just in case.

[BrianinMichigan]

You should have about 7 lbs of pressure to the carb.

[fishingbob61]

when I had a gasser with 454 it would do the same thing, I installed a in line fuel pump and that solved the problem was vaper locking I think

[Bruce_Brown]

Another vote for the fuel pump. While ours was a Ford chassis it would also do the same - 2 new fuel pumps (one on the rail, one in the tank) fixed it.

[Rvnoobguy]

I really appreciate the replies! I am definitely going to check fuel pump next since that seems the most likely culprit based on what I'm hearing.. I will keep you guys updated on if that fixes the problem.

[Son_of_Norway]

Seems like a fuel supply problem. Are you keeping the gas tank full? Maybe your fuel pump is overheating. I had similar problems and had to drop the gas tank several times to replace fuel pumps. I finally had enough. I installed an external fuel pump 2 years ago and I've had no problems since. If the external pump does go bad I can replace it in 20 minutes. I also replaced the wire going back to the fuel pump. There's too much voltage drop in the 30 feet of 16-gauge wire that came from the factory. I'm surprised that the original pump lasted as long as it did. The replacement pumps these days don't last anywhere near as long.

[sehunter]

I had an 85 Allegro that had that 454 in it and I rebuilt that carburetor myself and I would bet that the accelerated pumps not functioning properly or the fuel pumps failing my electric fuel pump was on the driver side frame. take the breather off get a flashlight look down the primaries and make sure there is a lot of gas pouring in when you floor it without the engine running.
Many years ago I would exchange a carburetor for a rebuilt one many times have to do that twice to get a good one.