135 gas, runs till hot then stops

[sch2046]

Help. I have a gas mf135, it has been loosing power, not as much pto power as before, it now sputters an quits after 35 or 45 min of use. The sediment bowl is boiling by this time, my thought was vapor lock, but I have. No idea,I just changed the coil. The design seems flawed, gas tank sitting on top of the engine,the gas in the tank. Will boil too. Am I on the right track? Is therea fix for the boiling gas?
Thank you,
Sean

 

[Larro Darro]

The fuel shouldn't be getting that hot. Does your temp gauge work? If so, how hot is the engine getting? It sounds like you might have an engine overheating problem.

 

[sch2046]

Temp gauge is always in the middle, never. Overly hot, just past the little dot on the gauge. I purchased a new thermostat, I was thinking the same thing. What steps would you take? I have not put the thermostat in yet??

 

[Larro Darro]

If the engine is not running hot, I don't know what to say. But since you have the thermostat, you might as well put it in.

I did a quick search to see if the 10% alcohol would change the boiling point. From what I saw, regular gas would boil first, leaving a higher percent of alcohol. I will copy and paste from Hot Rodders:


Specifications define the temperatures at which various percentages of the fuel are evaporated. Distillation limits include maximum temperatures that 10% is evaporated (50-70C), 50% is evaporated (110-121C), 90% is evaporated (185-190C), and the final boiling point (225C). A minimum temperature for 50% evaporated (77C), and a maximum amount of Residue (2%) after distillation. Vapour pressure limits for each class ( 54, 62, 69, 79, 93, 103 kPa ) are also specified. Note that the EPA has issued a waiver that does not require gasoline with 9-10% ethanol to meet the required specifications between 1st May - 15 September.

You will notice the figure 225 degrees C (about 425 deg. F) given as the boiling point- other sites place a wide range of 100-400 deg F. The exact boiling point will change w/altitude and the time of year- gasoline is formulated w/different properties depending on the temperature and geographical location.

If I were to take a WAG, I'd say that you're gonna be close at 375 degrees F.

And here is a good thread. It's talking about cars, but might help you out. http://forums.aaca.org/f120/can-boiling-point-gas-raised-289338.html

 

[Larro Darro]

I saw where they have problems in the high altitude of Colorado with boiling gas. They keep cold towels in their trucks to wrap around the carb. A small ice chest with two shop towels might help you work longer.

 

[sch2046]

Well, I went out to do some more investigating and realized I had an old mouse hotel built in front of my radiator, it covered about 4 inches of the lower section of my radiator. I will see how my temp is shortly......I hope it is this easy......

 

[The kid]

That's why they put that trap door on the front. If you are brush cutting tall grass, it's needs to be checked each and everytime. Is this on a Continental engine?

 

[sch2046]

That's why they put that trap door on the front. If you are brush cutting tall grass, it's needs to be checked each and everytime. Is this on a Continental engine?

I am not sure what engine? How would I tell? It still quit running again tonight after clearing the mouse hotel,out.

 

[Midniteoyl]

Clean the rad real good with some simple green and a hose... Then replace the thermostat and retest.

 

[namyessam]

Help. I have a gas mf135, it has been loosing power, not as much pto power as before, it now sputters an quits after 35 or 45 min of use. The sediment bowl is boiling by this time, my thought was vapor lock, but I have. No idea,I just changed the coil. The design seems flawed, gas tank sitting on top of the engine,the gas in the tank. Will boil too. Am I on the right track? Is therea fix for the boiling gas?
Thank you,
Sean

Are you missing the heat shield that wraps around the exhaust and intake manifold which keeps all the heat from the gas tank The design is, that it is open in front and allows the air off the fan to blow the heat rearward and down away from the gas tank.