Not having much luck posting on other boards about this, so thought I'd give it a try here.

I needed to replace the main port filter and a hose end in the hydraulic system of my Bobcat. Too many other things going on, so it sat for quite awhile until I got around to it. Tearing into the hydraulics was great fun and a whole adventure for another story, but got that all fixed and functional again.

But ever since then I've had a heck of a time keeping the thing running. Mind you, the Bobcat is thirty years old and I've owned it for twelve years now. But it has alway run and done what I needed of it. Basic four cylinder gasoline carburetor Wisconsin air cooled engine with points ignition.

First issue was the previous owner butchered up the wiring for the fuel shutoff solenoid and in pulling hydraulic hoses out I apparently loosened his taped (yes, he taped the wires back together) connection. Amazing that had actually worked for at least the past twelve years... New shutoff solenoid installed...

Started it up and ran it for awhile, but then the engine just slowed down and died after about ten to fifteen minutes. Trouble starting it and when it would run it would run for a couple minutes and just slow down and die. Figured that after sitting and with age that the carb could use attention and a rebuild kit was cheap. Rebuilt the carb, cleaned all the crap off and out of it, buttoned it back together, and adjusted the governor and all the linkages.

Started it up and ran it for awhile. Ran better than it has in the twelve years that I've owned it, but then the engine just slowed down and died after about ten to fifteen minutes. Trouble starting it and when it would run it would run for a couple minutes and just slow down and die. Checked spark and I was getting spark. Checked fuel and was getting fuel - but it was on the weak side so I figured a new fuel pump might help thinking that it wasn't getting enough fuel to keep it running. New fuel pump and while I was at it I replaced the fuel hoses from the solenoid to pump and pump to carb (the rest is metal tube).

Started it up and ran it for awhile. Ran about the same as after the carb rebuild, but then the engine just slowed down and died after about ten to fifteen minutes. Trouble starting it and when it would run it would run for a couple minutes and just slow down and die.

Are you seeing a pattern here?

The confusing thing is that when it is running it runs great. So I haven't bothered with things like checking compression or adjusting the points or anything like that. If it was something like that, it would run crappy all the time - wouldn't it? After the last attempt, I pulled the carb again and the bowl was full of fuel so it isn't starving. I've checked flow after the fuel filter (good gravity flow), after the solenoid (good gravity flow), and after the pump (good pressure flow). Air filter is good. Not running long enough that I'd think vapor lock is an issue. Likewise, took the fuel cap off the tank just to make sure it wasn't a clogged vent.

At this point I'm at a loss. It isn't like this is some whiz bang complicated setup. Should be that if you're getting fuel and spark you're in business - especially if it is running well some of the time.

Any suggestions?

You didn't happen to relocate some fuel lines during this, did you? Ours started vapor locking after we replaced fuel lines. Had to re-route them several times before it quit.

Doesn't sound like it, since you have fuel in the carb, but I thought I would mention it.

Vapor lock was my first thought as well. Would your Wisconsin engine be the V4 air cooled variety?

Nissan: I replaced all the fuel lines but didn't reroute anything. Also, things aren't running long enough for the engine compartment to get very hot.

LC: As the title states, VH4D and:

Basic four cylinder gasoline carburetor Wisconsin air cooled engine with points ignition.

Ours was vapor locking in under 5 minutes...

Is the new pump an oem replacement, or at least a matching pressure/flow?

I put an electric one on my garden tractor, and it would flood it out, and then eventually overheat and quit. I ended up putting a "T" and a needle valve on the pressure side with a return to the tank, so it had constant flow.

Sounds like it's getting too much fuel and flooding out after a while, could be too high of pressure that eventually overcomes the float?

One thing we did when messing with ours was to have one guy remove the gas cap, cover it up with his hand as best as possible, and use a blow gun to pressurize the tank somewhat, while the other started it.

All OEM replacement parts, so fuel pressure shouldn't be a problem.

Real stupid question, but what are the symptoms of flooding? I've had things flood out when trying to start, but never when running. For example, with the throttle at 3/4 it will run strong and then just start slowing down. Messing with the throttle doesn't change anything. And it isn't like it is struggling. It just slows down pretty evenly until it isn't running fast enough to keep going.

I've never had an engine behave like this so I really don't have too many more ideas of what to try.

The other thing about the vapor lock issue is that there is a "shelf" around the top of the engine that acts as a heat shroud and there is a grill above this space. Most of the heat is kept below this shroud and vented through the back access door of the Bobcat. The fuel lines, fuel pump, and carb sit above this heat shroud.

So I'm doubting that it is vapor lock. Also, it was never a problem before and I've not changed or reconfigured anything. Just replaced parts with same kind parts.

Nissan: The "over fueling" could be a possibility, but sort of strange for it being a OEM replacement pump. And even stranger that it is the same exact problem before the carb was rebuilt, after the carb was rebuilt and before the fuel pump was replaced, and then after everything was replaced. Weirdly, the main change has been that when it IS running it has been running better than it was before the repairs. But when it dies it dies exactly the same way... So both the carb rebuild and the fuel pump replacement resulted in improvements when it is running...

Have you replaced the points with a Pertronix unit yet? And have you looked at the exhaust to see if a rich condition exists prior to shut down. I'm going to guess that it's ignition related. If it was flooding you would smell it or see black smoke. Try hooking up a dwell meter and a timing light and see if things change when it dies.

The Pertronix unit has been on my list for a long time, but I've never really had ignition problems so I never got around to it. You bring up a valid point about the exhaust. There isn't any excessive smoke when it shuts down and my gut reaction has been that it isn't a fuel problem.

As it is, I stopped by the local dealer on my errands today and told them my tail of woe. Their head mechanic wasn't in, but the service manager said he had a similar problem with an old Farmall.

It would run like a "raped ape" when you first started it but then slowly wind down and stop running - pretty much the experience I've been having.

He said the solution was a valve job. That as the engine warmed up the valves wouldn't seat properly, lose compression, and the engine would stop running.

That wasn't the sort of answer that I wanted to hear and was curious to me because before I stopped using it I wasn't having any problems. He was going to run it past the head mechanic tomorrow and let me know what the mechanic thinks.

Try using a different ignition Coil. Possible you're existing one is experiencing a thermal breakdown once it's been running for a while. (How's that for a WAG?)

I suppose it is as good of a WAG as all the others... :)

I'll see what the mechanic says tomorrow. I'd like to get it fixed without continuing to randomly throw crap at it.

RCBrett hit the nail on the head... :)

I think that we're back in business now!

The two problems that I've been having are the fact that it runs so well when it is running and also that life intervenes and usually several days (at least) pass between the times I have to sit down and work on the machine.

Although it seemed like I was getting a decent spark, in the interest of eliminating things today I swapped in the coil for my pickup truck. Fired right up (usually, it has to crank for a moment before firing) and ran strong. Didn't really have too much to do with it today, but it definitely ran long enough to verify that was the final problem in the mix.

Just in the interest of tying up loose ends, I'm going to put a new coil, spark plug wires, and spark plugs into it and call it a day.

Right on.. good to hear you got it nailed down.

I love those little Wis-Con V-4 engines. I've got a new one out of a concrete saw in my garage collecting mouse turds until I think of a project for it. I may end up using it for a backup generator for the house... or just go-kart from hell.

Can you take a pic of what these little engines look like??

Are they L-Head or OHV??

Like this (see below). Four cylinder, OHV, air cooled, V-block, 20 to 30 hp.

We had one powering a log splitter.
What an animal! Didn't need no stinkin' 2 stage pump !!!
Didn't start too well after it got hot, but doesn't take long to cool off in Iowa in December!
Ash splits better frozen.

My dad fought his generator for months, it was the same thing run for 10-15 min then die. Carb kit, different fuel tank, new lines and filter none of it fixed it. He finally caved in and took it to a small engine shop fifteen minutes and 25 dollars latter they had a new coil on and Dad had his gen back running like a top.

I have to admit that the Bobcat now runs like a raped ape - better than it has in the twelve years I've owned the darn thing. The coil was likely the culprit all along, but rebuilding the carb and putting in a new fuel pump wasn't wasted money. It forced me to go through things and get it all tuned up. Basically, it has always run since the day I bought it so I never bothered to mess with it.

Those Wis-Con motors are tough little buggers too. Tapered Timken bearings on the end of the main, so you can set them up to belt drive stuff and they don't care about the side-loading at all.