1990 Fleetwood Bounder/Vapor Locking

HI,

what are the actual "symptoms" of your engine? Does it overheat? Has it always had this problems or did it show up after a repair? Has the original cooling system ever been modified?

The engine has never over-heat it, and I just had a full tune-up spark plugs,cables,cap and rotor you know the hole nine yards. And it only happens when it really hot 100 + F, other than that it runs like a Champ. When it happened I will pull over and wait for 10-15 min and it will start again, on the cooling system it has two electric fan. What do you think on the fuel pump? it still works but do you think may be is going bad? Thank you very much for your time.

Crossfire Alex

I learned how to drive in a 1974 toyota fj40 that had a 327 chevy small block in it.

Vapor locked all the time. we first tried a sheet metal heat sheild (it also had an inline fuel filter in the engine compartment). We ended up re-routing fuel lines, insulating fuel lines, heat sheilding the manifold, and moving the filter.

Nothing to it!

CR3

Thank you I'll try that..

What about having an electric gas pump installed????

What about the gas psi? Is an electric fuel pump will have too much presure?

Re: 1990 Fleetwood Bounder/Vapor Locking.

Many of my friends had lots of problems with older motor home engine failures. Most failures were traced to heat. Doing 70 mph down the freeway and pulling into a rest area and shutting down the engine, left a lot of heat remaining inside engine and with no air flow through the radiator cooling the engine compartment it causes problems. To help remove this heat, a new electric radiator fan or maybe even 2 of them were installed in front of radiator, these fans are temperature controlled, the same as in the new cars today. When the big hot engine is shut down or even slows down, so is the engine cooling fan, not the elelctric radiator fan, it keeps running to cool that hot engine compartment. this is one possible way that may help stop that vapor lock problem. I never again want to be stuck in the middle of Montana in a 1951 Ford with a vapor locked flathead motor in 106* heat as I was in 1955.

I would suggest try running with the gas cap loose (or try a new one )this may indicate

the vent was not working . We used to have to burp our Husky chainsaws on hot days

due to vapor lock .

I have put a new gas cap about two months ago and still does it.

Thank you.

I actually have two electric fan, and still get vapor lock. When it vapor locks I loose power as the motor home dies I pull over for about 10-15 Min's and it will re-start for may be half an hour to an hour and it will do it again, as the temperature out side decreases the RV will go longer with out stalling. Thank you for your time and help.

Crossfire Alex,

I've seen people put wooden clip-on clothespins on the fuel line to dissipate the heat.

So the old timer who told me that one was not just blowing smoke. Still can't see how it could work.

It is funny you said that because I have heard this one before but I thought it was just a joke, do you think it would work?

Thank You.

Clothspins are cheap.

This sounds more like an insulating measure than one that would dissipate heat.

Anyone for a char-grilled clothspeg?

Untill now I've never been confused about the term 'vapour lock'. I always accepted this to mean a fuel vaporisation problem, where the fuel feed breaks down in high ambient temperatures. Not a problem with the cooling system, (which of course also tends to suffer more in high ambient temperatures). I've found unleaded fuel more prone to this than the old stuff. Given that high ambient temperatures aren't that unusual in the States I'm surprised the manufacturers haven't encountered the problem and found a cure for it in their testing. Some have even had to resort to heat exchangers off the aircon system.

Another CR4 thread very recently covered the very same.

In Montana in 1956, the old 1950 Ford was very prone to vapor lock at high altitude and high temperatures. The conventional cures at that time involved wet rags on the carburetor. Grapefruit supposedly would provide a more sustained cooling because of the cells releasing their water slowly. I don't know if these cures worked because we had usually been stopped for 10-15 minutes and the vapor lock had cleared by then.

If you have a fuel pump that is on the motor, the suction in the fuel line will certainly lead to vaporization. Installing an electric fuel pump in the tank seems to eliminate vapor lock. A retrofitted pump could be dangerous if the fuel system is not designed for it. I would be very careful, especially with a motor home and all the flamable construction around the motor.

The motor home comes with an electric fuel pump right now, do you think I should replace it?

Thank You Crossfire Alex

Try attaching some aluminum foil to the fuel line with "binder" clips. In effect extending the surface area of the tubing and assisting cooling. Also helps by reflecting some of the radiant heat away.

So, the aluminum foil works!!!! I have heard this one too like the wooden cloth clip.

Thank You,

Crossfire Alex

I have seen the same stalling wait 15 minutes actually be the coil

It's a quick and easy thing to try

I have seen more modern ignition moduals do the same

best of luck

Thank You for the feed back!!!!!!!!!!!!

My friend also has a Bounder, a 1994 model (I think) and he solved the vapor locking problem by mounting a phenolic spacer between the carb and the intake maniflod.

He was told that in hot conditions the heat from the manifold will raise the temperature in the carburator until the gasoline in the carburator float bowl boils. This boiling gasoline starves the engine of fuel causing the engine to stall.

These spacers are available from most any auto parts store. Try www.socalautomotive.com if Pep Boys or AutoZone can't help.

Thank you very much for the information, I will look in to it.

A few thoughts:

Don't modern fuel systems with a submerged electric fuel pump run at constant flow rate and use a fuel return line back to the tank? Wouldn't this have the effect of reducing any vapor lock potential in that portion of the system? (Right up to the carb or fuel injection module.) Does your vehicle have this return system?

I would double check whether the fuel cap is really venting. That time interval seems quite specific. New doesn't alway mean good.

I have seen older engine driven mechanical fuel pumps cause exactly the same symptoms you list. The pump still works, but has not completely failed. Our car was fine unless pulling a trailer or on the freeway. It meant that we got an extra week of vacation while the mechanic tried to figure this out.

Have you double checked the fuel filter? Not plugged? The element isn't slowing deforming with fuel draw?

I recently talked with an RV owner who described almost similar symtoms. He had lowered one of the fuel tanks in order to fix a leaking hose. When he raised the tank back up and tightened the straps the tank apparently deformed a bit. This pushed the fuel pickup too close to the bottom of the tank, preventing full, free flow. As long as the tank was nearly full it seemed to work. So each time they left on a trip with full tanks it ran fine. Once they got out in the middle of nowhere it would start missing and eventually quit.

Does it do this when driven hard at night when it is cooler? What if you run the heater full blast during test? Does the ten minutes turn into 15?

I check up underneath and all i see is one fuel line not two so I do not think that I have the return system, also at night it runs like a champ and also try the heater no luck with that ether. Thanks for the help.

We had the same problem with our 1996 Bounder with a Ford 454 engine and fixed it by replacing the fuel pump. After the replacement 3 years ago it has never occured again.

That will be my next step, I will replase the fuel pump and the gas filter, Thank You.

start with new, exact specified radiator cap.

Never mind the rad cap, the problem is the fuel vapourising. The water isn't boiling but the fuel is. If the thing isnt fitted with the insulating carburettor gasket, then it's the first thing I'd change. Is your electric fuel pump near the tank low down, at the lowest point hopefully?