Community Forums

Hydrover · 09-03-2011, 12:36 AM

Hey Folks, i have one of them older type RVs, a 1979 Georgie Boy on a Dodge M500 chassis, 440 engine and Torque-Flight 727 Xmsn..
I am trying to figure out what engine and tranny should I go to in order to eliminate the problem of the engine not liking the modern gasolines.

every thing runns ok but with difficulty, running down road after 30 miles the thing acts as if the engine is about to stall,

, I shift to neutral and it revs fine w/no sputter, back into gear and sputter and choke as if no fuel getting to carb

,
I tried contacting the Dodge people and they just laughed it off and sugested a totaly new RV,, I should be able to find a suitable power train package that will run the new fuels and get us back on the trails by next season,,, if only I knew what I needed to look for....
Any sugestions????

Midniteoyl · 09-03-2011, 01:11 AM

Why do you think you need a new engine? That 440 should run fine with todays fuels... You prolly just need to clean and adjust the carb..

You should get a good local mechanic to have a look... could be something as simple as a stuck choke or bad float... Or the carb might need rebuild.

Also, is this an electronic distributor? Do you have the silver 'computer box' on the fire wall? Or is it still points (highly doubtful).. Distributors do go bad.. as do coils and ballast resistors...

What you describe doesn't sound like you need a new motor, just some maintenance and adjustments to this one.

If you still wanna swap it, stop by here.. I'll swap you for a Ford 460/C6 trans combo....

Dave78Chief · 09-03-2011, 08:04 AM

Possibilities:

A) EGR valve sticking open resulting in lean burn condition. EGR allows exhaust gas to be recirculated into intake stream below carburator.
B) Rubber fuel lines on top of fuel tank old a cracked allowing the fuel pump to suck air.
C) Fuel filter at fuel pump clogged resulting in low flow rate.
D) Stock exhaust system has been modified resulting in more heat being generated around fuel lines (passenger side frame rail) causing vapor lock.
E) Fuel pump getting weak.
F) Thermoquad carburator needs to be rebuilt.

Dave

mahon1993 · 09-03-2011, 08:09 AM

You need a mechanic that works on older cars, maybe even one that races Mopars, maybe a drag racer or sprint cars. Ask around, make some calls. Your problems can be fixed. You don't need a new engine unless it's blown.
Greg

Hydrover · 09-03-2011, 08:14 AM

thanx for post mr midnightoyl
the ignition module is new and have a spare, yes engine will run on the new stuff but not well enough to trust for long haul. I just want this thing to go when ever WE want to instead of when it wants to, and if the other half wants to take her girlfriends on a ladys only trip, I want it to not need tinkering with. we have had it a year now and three trips to a local lakeside, total of 10 days, eight of em spent working on the drive train, some way to relax eh?,,,

Ed-Sommers · 09-03-2011, 08:36 AM

The fuel is not the problem, I have no idea why you would think it is;

Your fuel delivery system is whats at fault, just fix it, or have it fixed.

Ed

Hydrover · 09-03-2011, 08:51 AM

EGR is new,, fuel line? will put new on to eliminate,, exhaust is original no sighn of mods,, fuel pump is electric and provides 25 psi @ carb intake,, removed the 5 inline fuel filters and installed a larger marine type Racor that will filter @ arate of up to 10 gallon per minute and it is a water seperator too,, carb rebuild? Who to trust??,, old motor mechanic------- most local mechanics are either starving or have totaly retired in my area that I have looked for. the starving ones see big dollars and want up front deposits and high shop time rates to work as slow as they can get by with to lenghten the trouble shoot process. the last one wanted me to bring it and leave it with him a few days, with a sign in the shop listing hourly rates of $75 per hour and $15 per day storage fee whether or not he is activly working on your vehicle or not and a $5 per hour additional charge
if you want to watch..

will try the total fuel line replacment theory next

thanks again all

Dave78Chief · 09-03-2011, 09:36 AM

25psi? I hope not. Spec for your TQ is 6-7psi max (actually thats for 4 barrel carburators in general). Values much higher than that will start pushing the float needles out of their seats because the floats are not strong enough to hold it back.
I know what sort of situation you are facing because I am fighting a simular issue on my 78 Chieftain with a 77 M400 chassis with a 440-3. It is a vaporlock problem. I have a clear glass fuel filter mounted at the carb with a fuel pressure gauge mounted on the output. After 12-30 miles of driving it vaporlocks with no liquid gas visible in the glass filter and the fuel pressure gauge still says 6 psi. Thats actually 6psi of air pressure not liquid pressure. I also have the same type glass fuel filters mounted on each tank suction line. It appears I had air bubbles in the lines which I think indicate air leak (most likely the rubber hose).

I have the TQ sitting 3 ft from my desk at the moment that I just rebuilt so I know what they are. Just have to get the time to go put it back on my 77 M400. I also have:
A) Dropped the main fuel tank, cleaned it out and have to reinstall it with new rubber line.
B) Installed all new 3/8 fuel line outboard frame rails that is as far as possible from the exhaust system. Same approach GM did for their P30 problems in the late 80's.
C) Moved tank select switch to outboard the frame rail. Original design (pre ethonol days) had it mounted next to the muffler with a heat shield.
D) Converting to a 14psi pump with a 6psi regulator at the carb. Object is to increase the PSI in fuel line to help overcome the potential vaporlock issue. Dodge never installed an electric pump so those are always aftermarket add-ons.

As you can see, I am a little familure with the problem you are facing. Just have not got it all put back together yet to see if I have solved the problem.
I also suspect the 100 degree days in Texas are not helping your situation much either.

Dave

Dave78Chief · 09-03-2011, 09:48 AM

I forgot to add, I have been looking at the possibility converting to a GM 454 TBI based system. The recirculating fuel system is partly how the chassis mfg's solved the vaporlock problems.

Dave

Hydrover · 09-03-2011, 09:57 AM

ok well may not actually be 25 psi,, just better have a face shield on when taking lose the hose to check the fuel flow with fuel pump turned on the fuel skeeted all over me and shot down the inside past the galley fridge,, plenty of pressure!!
I had one mech. say the torque flight xmsn was a tuff model even after he dumped a quarter cup of shavings outta the xmsn pan,, he said that was normal and it oughta run longer than the motor would.. /??? would a worn torque converter cause the engine to sputter and stall as if no fuel, then, while still rolling shift to neutral and the engine runs and revs without hesitating, put back in gear and sputter, stall and backfire until you stop for a few hours,,
this is very frustrating, can't get anywhere going 20 miles at a stretch before resting the driveline.

Hydrover · 09-03-2011, 10:03 AM

recirculating fuel system??? what if,, 5/16th fuel line from tank through filter and pump to Tee fitting at carb then reduce to 1/8th return to tank..
would that eliminate vapor locks and allow enough fuel to run???

Dave78Chief · 09-03-2011, 10:08 AM

Breaks down under load after reaching operating temp. Runs ok until engine warms up.

Is that correct? In order to list possibilities I am trying to determine if the rig runs OK when the choke is on resulting in a richer mixture.

Dave

Dave78Chief · 09-03-2011, 10:11 AM

If you want to do a recirculating setup, get a higher pressure pump and a bypass regulator (6-7 psi). If you have a fuel tank select switch, then you will also have to have a return type version (6 hoses) rather than just a standard 3 hose switch. Achievable but you have to understand how it works.

http://www.jegs.com/c/Fuel-Carbs-Int...10323/10002/-1

Dave

Wanabee FTer · 09-03-2011, 10:12 AM

I would hate to be un-mechanically inclined and own an older MH. Too many shade tree mechanics out there that just want to replace parts until the problem is solved. Very few are capable of truly diagnosing a problem.
I would tend to agree that it may be a fuel delivery problem, quite possibly vapor lock or carb float problem.