Need some ideas! I took the motorhome out today after it has sat for a few months, and it acts like it's running out of gas while going uphill. Runs great otherwise. Pulls hard on level ground,water temp is normal range. It's a class c 79 Dodge with a 440,Thermoquad,dual exhaust. The fuel filter looks like it's been there a couple of decades, so I'm gonna change it out tomorrow. It has an electric fuel pump at the tank, which feeds to the mechanical pump on the motor. I tried it with the electric pump on, and off, and it still will fall on it's face uphill. Any help is appreciated.

Fuel filter sounds like a good idea. Another diagnostic would be to pull a fuel line off near the engine and run the electric pump for a flow test (with engine cool and off). If the pump is weak or there is a blocked line you would be able to tell.

Yep...gonna run it into a paint strainer and see if it catches any junk. Can't imagine it would be rusty, since the tank is plastic. I'm really hoping the filter fixes it. My wife is about heading out across the mountain with it acting up. Gotta say I am too!

put some fresh gas in it.
I think todays gass goes bad as it comes out of the pumps at the station...

Is this problem actually related to the grade of the hill or the deep throttle it takes to climb a hill?

the steel line will rust with a plastic tank

check the oil for gas smell while messing with the Fuel pumps

stock ones can dump into the pan if ruptured

check fuel pressure/supply at the carb

got the timeing set and carb dialed in with a vac gauge?

dont take long for the gas to go bad

maby rig a can for a test ride to rule out fuel line

pin holes and air bubbles can come from the steel line with plastic tank as well

I kind of think it's the grade of the hills thing. I ran it hard all the way thru 2nd gear on level ground, and it never stumbled. It's just like it runs out of gas all of a sudden. I can peddle the throttle some, and it will catch back up for a second or two till it runs out of gas again. I'm going to cut the old filter apart when I change it to have a look.

sounds like filter is the right track

my /6 would do that,feather it some slowing down it would pick back up,then die off agin

cut the filter open,it was full of rust and gunk

good luck

Thanks Mike. I'm really hoping the combination of old gas and the filter from the 80's may be the problem. When I drove the thing home from SC, it never missed a beat....and I had a pretty long uphill climb. I had just filled it up right after picking it up, so all that gas was good. It has sat with the remainder of that fillup since March. I hope to have good news to report tomorrow.

fuel pump push rod worth checking....

Sounds like a carb float issue to me, my car was doing the same thing.

Could be a fuel pump issue. When my fuel pump was dying it would not keep up with the fuel needs under heavy throttle. By the time I got much into 3rd gear at full throttle from a stop it was running out of gas. Let off it for a few seconds for the pump to refill the bowls and I could get back on it again for a few seconds.

Yeah ..... good thing to look at ... is this only going-on uNder WOT ?

JD ... GET a fuel pressure gauge on your motorhomey YESTERday !!

Another thing to check are the short lengths of rubber hose that connect the steel lines and electric pump. I'm helping on an old Ford pickup that had intermittant fuel starvation. Couldn't figure it out until I was crawling under the pickup and started squeezing the rubber lines. Some of them were soft like they were made out of plastic wrap. Any suction pulled them closed. They were not only old but probably not compatible with alcohool in today's gas. A couple feet of 3/8" fuel line fixed the problem.

Got it fixed!! AHY was pretty close to what it was! I ended up dropping the tank when the inline filter up by the transmission didn't pan out to be nasty. When I dropped the tank,I found the 5/16 rubber line that goes from the tank to the electric pump in the back....was smushed in one place and rotten in another place with a hole in it. It was sucking air big time! I took the pickup out of the tank, and the sock looked like it had been drug down a red clay Georgia road for a hundred miles. Wouldn't clean out no matter how much I sprayed it with cleaner....so I tossed it and cut a filter in line between the tank and the electric pump. I also changed every piece of rubber fuel line on the beast! I cleaned the tank out,put new gas in it...and no more stumble! Took it up the toughest hills I could find, and no problems at all. Thanks for all the ideas.

So with THIS fixed ...and new front brake hoses ...it is Bristol time ?

That it is Doc! Checked all the lines and stuff out tonight....and it all works. I gotta get a bigger gray water tank though. The one on it is way too small. I can do that AFTER Bristol

I hope the filter you put in front of the electric fuel pump is the same microns as the sock in the tank. Most filters are designed to go after the fuel pump and are around 10 microns which is too fine to suck through expecially in hi heat conditions, hi alitude conditions and hi load conditions.
It'll also shorten the life of the pump.
Something to think about if it struggles under the conditions I mentioned.

Thanks Gary. I'll keep that in mind. The electric pump was an add on that was installed by the last owner. It's just a dinky little thing mounted on the frame, right in front of the tank. Easy to change if it takes a dump. All it really does is give the fuel a boost to get to the mechanical pump on the moder.