gas leaking bobcat

[Quicksand]

I have recently purchased a bobcat 610. It sat outside for the past 4 years.It has 14000 hours. I have painted it, replaced the plugs, points, new electric fuel pump & lines, tank pick-up tube, muffler, oil & filter, hydro. oil & filter, and drained the gas tank due to water and rust. I got it going, used it very little around the yard on very hot days and found out it vapor locks. I tried moving the lines, wrapping with tinfoil, and all that stuff. It still did vapor lock. I noticed that the cab on it actually traps heat by not venting out the top. Assuming this is a big factor of the vapor lock, I cut away some metal so heat can escape. Ready to test it today I found out it was out of gas AGAIN. It appears to have a leak. I lost approx. 6 gallons over the past few days. I don't see anything dripping gas, the ground is dry, I am stumped. I wondered if it mixed over into the hydro. fluid tank since they are together. The gas being only 1" deep and the hydro. fluid is several inches deep tells me that is not the case.
I plan on placing some cardboard under it and adding gas back to the tank so I can look and smell for a leak. Any other Ideas? Is there a common gas leak?

 

[TraderMark]

I'm not familiar with this particular model machine, but one thing I would do would be to check the engine oil and see if it was over full. If there's a mechanical fuel pump, the diaphragm could be leaking, allowing your gas to enter the engine's crankcase.

Mark

 

[Quicksand]

Thanks for the reply. I have an electric fuel pump mounted up on the back side of the cage. It seems strange I did not see or smell the gas. It must be leaking
someplace out on the ground then drying up before I get back to it. I thought I would ask around to see if anybody else has had their bobcat leak gas and what they did to fix it.

 

[DJ54]

No answer for the gas leak, but do have a question for the vapor lock.

Does it still have the VH4D Wisconsin, or repowered with like the B&S Vanguard engine.??

I have a 450 with a 18 hp twin Kohler I bought from an equipment rental company. They installed an electric pump on it, I assumed it was a factory setup.. It too on hot days would vapor lock, or so I thought. It had the Facet elec. pump on it. When it quit working, I replaced it with a Mr. Gasket 4-7 psi micro pump. It is actually the electric fuel pump getting hot, and the little occilating piston seizing up, until it cools. They are a 35 gph pump, and if there is no return/bypass, they get pretty toasty.

I thought I would get the Mr. Gasket pressure regulator, and set it to like 2 lbs. pressure, and put a "T" in the supply line, so as to return excess fuel to the tank. More or less working like a municipal water system. Nope..., same thing.

Two years ago I bit the bullet, and bought the original mechanical pump for it. The reason they say they went with electric, is that it is a PIA to get to the mechanical pump. After looking, 6 or 8 bolts out, and slipped off the drive belt, I had the engine slid out the back on two 6X6 blocks. 15 minute job to switch out fuel pumps. It's ran like a charm for two years, and not missing a beat, doing the same thing it has before in the heat.

Next time you cold start it, listen to the sound pitch of the pump. If, and when it appears to vapor lock, listen to the pitch of the pump then, and or go around, and carefully touch the pump. Bet it will be pretty warm..!!

Unless it came with an electric pump from the factory, I'd try to find a mechanical pump for what ever engine may be in it.

 

[Quicksand]

Thanks for the reply. That makes sense. I have that same Mr. Gasket electric fuel pump on it. I did notice that it gets very very hot back there by the engine.
I was thinking of moving it up towards the front, until I realized the cab-cage was not venting out of the top back there. The cage that is on mine acts like a
balloon not letting the heat escape. Having the original pump down low must help keep it cool. Once I figure this gas leak out, I'll most likely be back to
working with the vapor lock. This bobcat is great when it wants to run right, otherwise I spend more time working on it then anything else. Sure glad this is just a cheap 30year old tinker toy.