Bobcat M600 won't start - help please

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Hondaman900

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I just bought an old M600, unknown age (I'm told late 60s'), but 700 hrs on a factory-rebuilt engine. It seems to be in good shape but wouldn't start as the wiring harness had been badly patched and there was no voltage to the coil. Previous owner said that a wiring fault prevented it from starting, but once started it ran great.

I ran 12V to the + side of the coil and now have a good spark. It cranks strong and I can squirt starting spray into the carb air intake and get it to fire up for a second or so. After many attempts to start it and much cranking, the plugs are still dry. I traced fuel to the intake side of the fuel pump but the out port of the fuel pump is dry. I'm positive if I can get fuel to the carb it will run well.

Any ideas? There is a tiny lever in the manifold at the base of the fuel pump. What is it and does it enable/disable the fuel pump? Am I looking at a faulty fuel pump, and if so is this a servicable part? Does the fuel pump/carb have to be primed, and if so how?

Also, I have the Melroe maintenance manual. It refers to a specific starting procedure. Can anyone tell me what that is? It has little or no reference to the fuel pump.

Many thanks. Any help is very welcome.

Stephen
 

140mower

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Hi there, While I have no experience with your model, I've been playing with small engines in garden tractors etc for years. To confirm it is a fuel delivery problem you could use a fuel tank from an outboard engine placed above the engine and gravity feed it. If it fires right away I'd say your pump is shot, and most can be rebuilt of that vintage. If parts are not available or the pump can't be rebuilt, you can bypass it using a small electric pump in it's place. if the engine hasn't been run for a long time, it would be a good idea to remove the carb and dismantle and clean real well as they can get gummed up pretty good as the fuel evaporates off. Be sure to clean all the passages real good as they are small and the slightest restriction will effect performance. One other thing I'd do is confirm you don't have a restriction in the fuel line going back to the tank, this can be done by blowing air into the line and listening at the filler cap. If there is fuel in the tank you should hear the air bubbling, if it only hisses, you may have a broken pick-up tube inside the tank.
Hope some of this is of some value to you. Let us know how you make out, and hopefully someone more familiar with your machine will chime in soon.
Don
 

skidsteer.ca

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Hi there, While I have no experience with your model, I've been playing with small engines in garden tractors etc for years. To confirm it is a fuel delivery problem you could use a fuel tank from an outboard engine placed above the engine and gravity feed it. If it fires right away I'd say your pump is shot, and most can be rebuilt of that vintage. If parts are not available or the pump can't be rebuilt, you can bypass it using a small electric pump in it's place. if the engine hasn't been run for a long time, it would be a good idea to remove the carb and dismantle and clean real well as they can get gummed up pretty good as the fuel evaporates off. Be sure to clean all the passages real good as they are small and the slightest restriction will effect performance. One other thing I'd do is confirm you don't have a restriction in the fuel line going back to the tank, this can be done by blowing air into the line and listening at the filler cap. If there is fuel in the tank you should hear the air bubbling, if it only hisses, you may have a broken pick-up tube inside the tank.
Hope some of this is of some value to you. Let us know how you make out, and hopefully someone more familiar with your machine will chime in soon.
Don
140 gave you a excellent place to start, I'd just add that a small squirt bottle with a little gas can be used to feed the engine straight into the carb. If the rest of it is good you should be able to act as the carbs fuel delivery system long enough to confirm spark and compression are all in order. If you can make it run on the squirt bottle, then are you need to do is fix the carb or fuel pump and you good to go.
regards
Ken
 

Hondaman900

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140 gave you a excellent place to start, I'd just add that a small squirt bottle with a little gas can be used to feed the engine straight into the carb. If the rest of it is good you should be able to act as the carbs fuel delivery system long enough to confirm spark and compression are all in order. If you can make it run on the squirt bottle, then are you need to do is fix the carb or fuel pump and you good to go.
regards
Ken
I picked up an electric fuel pump that's 1.5-4 lbs and will hook this up to see if that works. I also ordered the operators manual fom my local dealer for $15 ($36 on eBay!), which should help. I'll post progress.
Thanks for all the help, and if anyone has anything else to add, thanks in advance.
 

Hondaman900

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I picked up an electric fuel pump that's 1.5-4 lbs and will hook this up to see if that works. I also ordered the operators manual fom my local dealer for $15 ($36 on eBay!), which should help. I'll post progress.
Thanks for all the help, and if anyone has anything else to add, thanks in advance.
Well, looks like that little lever is for priming the fuel pump (you can hear it manually movnig the diaphram). I took the fuel pump intake hose off the fuel filter and put it in a cup of gas and it sucked it through without a problem. I blew into the gas tank through the hose that went to the other side of the filter and air flowed freely into the gas tank and I heard loud bubbles. The fuel filter is the only other thing in the fuel line, so I'll pick up a replacement this evening and fire her up! (I hope).
 

Hondaman900

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Well, looks like that little lever is for priming the fuel pump (you can hear it manually movnig the diaphram). I took the fuel pump intake hose off the fuel filter and put it in a cup of gas and it sucked it through without a problem. I blew into the gas tank through the hose that went to the other side of the filter and air flowed freely into the gas tank and I heard loud bubbles. The fuel filter is the only other thing in the fuel line, so I'll pick up a replacement this evening and fire her up! (I hope).
Success!!!
The new filter did it. Once the carb got gas flow it fired right up and runs strong and smooth. I used a clear filter so that I could see the condition of the gas, and there's water in there, so now I need to find the drain hole for the gas tank.
Anyone know where this is?
Thanks
 

Tazza

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Success!!!
The new filter did it. Once the carb got gas flow it fired right up and runs strong and smooth. I used a clear filter so that I could see the condition of the gas, and there's water in there, so now I need to find the drain hole for the gas tank.
Anyone know where this is?
Thanks
If there is only a small amount of water, add some FRESH metho. The metho combines to the water and allows it to burn. Its a cheating way, but works very well, unless its 1/2 a tank of fuel and 1/2 water! The metho must be fresh as it absorbs water from the air.
Glad you got it working! something as simple as a filter...
 

skidsteer.ca

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If there is only a small amount of water, add some FRESH metho. The metho combines to the water and allows it to burn. Its a cheating way, but works very well, unless its 1/2 a tank of fuel and 1/2 water! The metho must be fresh as it absorbs water from the air.
Glad you got it working! something as simple as a filter...
Those are the kind of fixes we like to here.
Helps me justify buying another neglected piece of junk and willing it back to life. :p
Ken
 

Hondaman900

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If there is only a small amount of water, add some FRESH metho. The metho combines to the water and allows it to burn. Its a cheating way, but works very well, unless its 1/2 a tank of fuel and 1/2 water! The metho must be fresh as it absorbs water from the air.
Glad you got it working! something as simple as a filter...
That sounds great! What's metho and can I get it at my local auto parts store? I've already clogged the new filter with rust particles from the gas tank. I really need to find the drain plug and drain out all the crap.
Any ideas where the drain plug is on a 600?
 

Tazza

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That sounds great! What's metho and can I get it at my local auto parts store? I've already clogged the new filter with rust particles from the gas tank. I really need to find the drain plug and drain out all the crap.
Any ideas where the drain plug is on a 600?
Metho is methylated spirits, you should be about to buy this at any shopping centre.
As for the rust particles..... thats not as easy, that means you have rust in the tank and its really hard to get rid of. I have a generator with this problem, it keeps cloging filters. I'm considering mixing up a fair amount of epoxy glue and pour it in the tank and turning it all around so it coats the entire inside of the tank to seal the steel from moisture. Then drill out the hole that the fuel comes out of.
I tried cleaning the tank with acid, which removed all the rust but it keeps coming back!
Good luck with it. You will get it sorted out.
 

m610

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Metho is methylated spirits, you should be about to buy this at any shopping centre.
As for the rust particles..... thats not as easy, that means you have rust in the tank and its really hard to get rid of. I have a generator with this problem, it keeps cloging filters. I'm considering mixing up a fair amount of epoxy glue and pour it in the tank and turning it all around so it coats the entire inside of the tank to seal the steel from moisture. Then drill out the hole that the fuel comes out of.
I tried cleaning the tank with acid, which removed all the rust but it keeps coming back!
Good luck with it. You will get it sorted out.
I have cleaned my fuel tank with muriatic acid, then neutralized with lime and water, and that got rid of all rust. After much cleaning and rinsing with pure water (collected from air conditioner) I dried it with a rag on a stick then applied fuel tank liner from JC whitney. That was over 10 years ago and there has been no rust. Epoxy I tried in small tanks but it seperates from the metal and water gets inbetween. My mulcher had rust in the tank to the point of holes, but I split the halves and after the acid coated it with lead/tin mix, then more lead. It never rusted again!
 

Tazza

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I have cleaned my fuel tank with muriatic acid, then neutralized with lime and water, and that got rid of all rust. After much cleaning and rinsing with pure water (collected from air conditioner) I dried it with a rag on a stick then applied fuel tank liner from JC whitney. That was over 10 years ago and there has been no rust. Epoxy I tried in small tanks but it seperates from the metal and water gets inbetween. My mulcher had rust in the tank to the point of holes, but I split the halves and after the acid coated it with lead/tin mix, then more lead. It never rusted again!
I'll have to look for fuel tank liner..... It sounds like a better option than my glue idea
The tank is far too big for me to split it and coat with solder i'm afraid :/.
 

sterlclan

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I'll have to look for fuel tank liner..... It sounds like a better option than my glue idea
The tank is far too big for me to split it and coat with solder i'm afraid :/.
http://www.eastwoodco.com/ they sell a liner kit that works well Good luck Jeff
 

Hondaman900

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http://www.eastwoodco.com/ they sell a liner kit that works well Good luck Jeff
So last night I siphoned 5.5 gals of brown crap from the gas tank, and filled it with 5 gals of fresh. Started her up this morning and there seemed to be even more water and brown sludge. I went through 2 more filters, clogging each up in seconds. In frustration I opened what I thought could be the fuel drain and got gas-smeling water. I let that drain until I got clear clean gas even when I rocked the Bobcat, put my last fuel filter on and finally got nice clean gas through. It's clear now, and running great.
What an ordeal. If I knew that was the drain I could have used it first and saved a lot of grief. But that's how we learn, right?
Now I have to figure out why the brakes don't work well. Hopefully just an adjustment. Can't lose power on the slopes around my property. That would be a disaster.
Stephen
 

Tazza

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So last night I siphoned 5.5 gals of brown crap from the gas tank, and filled it with 5 gals of fresh. Started her up this morning and there seemed to be even more water and brown sludge. I went through 2 more filters, clogging each up in seconds. In frustration I opened what I thought could be the fuel drain and got gas-smeling water. I let that drain until I got clear clean gas even when I rocked the Bobcat, put my last fuel filter on and finally got nice clean gas through. It's clear now, and running great.
What an ordeal. If I knew that was the drain I could have used it first and saved a lot of grief. But that's how we learn, right?
Now I have to figure out why the brakes don't work well. Hopefully just an adjustment. Can't lose power on the slopes around my property. That would be a disaster.
Stephen
Glad to see you have it sorted out, i would add a bit of methylated spirits to the tank just for good measure, it will adsorb any water that may be sitting in there.
As for your park brake, i'm sure it is just an adjustment. Mine is a little loose, i need to get under the cab and tighten the bolt that adjusts it.
 

Hondaman900

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Glad to see you have it sorted out, i would add a bit of methylated spirits to the tank just for good measure, it will adsorb any water that may be sitting in there.
As for your park brake, i'm sure it is just an adjustment. Mine is a little loose, i need to get under the cab and tighten the bolt that adjusts it.
I was using it for the first time this afternoon, now that it's running. After about 30 minutes of work, the engine started surging on its own, as if I was gunning the engine. Any ideas?
When I was done, I noticed that the fuel filter was close to the exhaust manifold and very hot, too hot to touch. Maybe I was getting vapor lock? I tied it out of the way for next time.
 

skidsteer.ca

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I was using it for the first time this afternoon, now that it's running. After about 30 minutes of work, the engine started surging on its own, as if I was gunning the engine. Any ideas?
When I was done, I noticed that the fuel filter was close to the exhaust manifold and very hot, too hot to touch. Maybe I was getting vapor lock? I tied it out of the way for next time.
Maybe vapour or another clogged filter. Now that its drained it should start to improve. Had a 371 with a poor gas cap esign that collected rain water and rusted the tank. You may want to keep a eye on the drain to besure rain is not getting in.
ken
 

Tazza

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Maybe vapour or another clogged filter. Now that its drained it should start to improve. Had a 371 with a poor gas cap esign that collected rain water and rusted the tank. You may want to keep a eye on the drain to besure rain is not getting in.
ken
It sounds like it leaning out, that can cause it to surge. When there is too much air without enough fuel it will rev higher, but it also burns hotter and creates more pressure. This can damage head gaskets and burn valves. Its something to try and avoid if you can, as far as i'm aware small doses like your getting now won't cause any damage, but keep an eye on it.
I can see that it could be vapour lock, but usually that will just cause it to stop working.
Try changing filters again as ken said, i'd try moving the fuel hose away from the exhaust. Add more fuel hose if needed to get it away from any heat sources.
 

sterlclan

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It sounds like it leaning out, that can cause it to surge. When there is too much air without enough fuel it will rev higher, but it also burns hotter and creates more pressure. This can damage head gaskets and burn valves. Its something to try and avoid if you can, as far as i'm aware small doses like your getting now won't cause any damage, but keep an eye on it.
I can see that it could be vapour lock, but usually that will just cause it to stop working.
Try changing filters again as ken said, i'd try moving the fuel hose away from the exhaust. Add more fuel hose if needed to get it away from any heat sources.
ON my machine if the govenor isnt adjusted right itll surge the book should tell you also you should check the shroud over the flywheel for mouse houses or other clogging stuff too much and no air gets around it will boil the gas in the bowl and do the same thing Jeff
 
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