642 Only Runs when it wants to. Need Help.

[Schifference]

Hello, I have this 642. It has been pretty consistently fussy. Sometimes it runs okay other times it runs then won't start. Today I put on a new coil and plugs. The points and condenser and cap were changed prior to me purchasing and look like new. There is an electric fuel pump. I pulled out the sending unit out of the tank. The screen looks super clean. I got rid of the original fuel filter and shut off and the electric fuel shut off solenoid. I ran new gas hose directly from tank to an inline filter prior to the electric fuel pump. I have fuel. A few weeks ago, This thing had not run for a month or so and I charged the battery and it would not start. I pulled the carburetor but it looks great and everything seems to be functioning. I put it back on and it still didn't start. I messed with the coil and plug wires and then it started right up. That was a few weeks ago. Today it won't start. I did mess with the point gap on the points and I am not certain if I have that set perfect of not. According to what I read, the gap should be .025. It is kinda hard to get that set. I messed with the points twice with not as much as a sputter. It started raining so I came in. I will verify that I have spark tomorrow. I did verify that I have power going to the + side of the coil. It appears to be about 8 or so volts. The coil I purchased has a built in resistor. I have no idea whether that is right or not but, it didn't run with old coil and doesn't run with new coil. I have new wires coming Friday. Another thing I did just because I was in there and all dirty and going to the auto store was I set the backlash on the valve rocker arms. I definitely have fuel. When it runs it seems to run pretty good. What can I do to make it run?

 

[Schifference]

Who knows what engine I can use when getting parts at NAPA? I have the Ford engine.

 

[Schifference]

Who knows what engine I can use when getting parts at NAPA? I have the Ford engine.

What I am asking is what should I say besides Bobcat 642 and give Bobcat numbers that do not crossover to anything. So as an example that 4 cylinder engine is the same as a 1975 Capri engine.

 

[Schifference]

What I am asking is what should I say besides Bobcat 642 and give Bobcat numbers that do not crossover to anything. So as an example that 4 cylinder engine is the same as a 1975 Capri engine.

I cannot say that I have figured anything out but as of this moment it is running and running good. I verified I had spark. I took out the fuel sending unit again and sanded it and inspected it. I plugged off the screened end and blew compressed air into it. Zero leaks. I hooked the fuel system back up and powered up the electric fuel pump. I disconnected the hose that goes from it to the carburetor. I added another pieces of hose and ran it into an empty 5 gallon gas container. Even when I shut off the electric fuel pump, fuel still running out from gravity. No issues with gas getting from tank. I disconnected the air intake from the carburetor, and opened the choke and pumped fuel into carburetor and it would not start. I then took a wrench and tapped the carburetor. Then don't you know it starts up and is running.

 

[Schifference]

I cannot say that I have figured anything out but as of this moment it is running and running good. I verified I had spark. I took out the fuel sending unit again and sanded it and inspected it. I plugged off the screened end and blew compressed air into it. Zero leaks. I hooked the fuel system back up and powered up the electric fuel pump. I disconnected the hose that goes from it to the carburetor. I added another pieces of hose and ran it into an empty 5 gallon gas container. Even when I shut off the electric fuel pump, fuel still running out from gravity. No issues with gas getting from tank. I disconnected the air intake from the carburetor, and opened the choke and pumped fuel into carburetor and it would not start. I then took a wrench and tapped the carburetor. Then don't you know it starts up and is running.

I took the carburetor off again. Ended up breaking the gasket. Ordered a kit. I noticed it has an antibackfire solenoid on it. If that is malfunctioning, it could cause a no run situation. I cut off the needle so it no longer functions. I guess I am going to be down for until I get the kit sometime next week.

 

[Schifference]

I took the carburetor off again. Ended up breaking the gasket. Ordered a kit. I noticed it has an antibackfire solenoid on it. If that is malfunctioning, it could cause a no run situation. I cut off the needle so it no longer functions. I guess I am going to be down for until I get the kit sometime next week.

I have found threads on this forum and maybe others where people have had problems like I have. One guy said his machine would not run than all of a sudden it ran just fine. What did he do? He sold the machine the next week. If I had to guess and after getting this deep into it, I would speculate that the real issue is the backfire solenoid. My machine is still apart awaiting the carb kit but the no run and runs great scenario sure seemed like an all or nothing thing. My guess is that solenoid closes and cuts off the fuel supply. If you are experiencing an issue like this I suggest removing the carburetor and then removing the solenoid and either replacing it, disabling it or plugging it off. If I had to bet, I would say that that solenoid has been the culprit of many bobcat owners problem.

 

[craigb93]

I have found threads on this forum and maybe others where people have had problems like I have. One guy said his machine would not run than all of a sudden it ran just fine. What did he do? He sold the machine the next week. If I had to guess and after getting this deep into it, I would speculate that the real issue is the backfire solenoid. My machine is still apart awaiting the carb kit but the no run and runs great scenario sure seemed like an all or nothing thing. My guess is that solenoid closes and cuts off the fuel supply. If you are experiencing an issue like this I suggest removing the carburetor and then removing the solenoid and either replacing it, disabling it or plugging it off. If I had to bet, I would say that that solenoid has been the culprit of many bobcat owners problem.

The solenoid is a problem and I have removed mine (742). That said, MOST of the solenoid problems come from using ethanol bearing fuel. Mine ran 20-years trouble-free until that stuff came on the market. Have only used ethanol free fuel for the last 10-years to remove that problem. Fuel pump diaphragms, brass carburetor fitments and fuel tank pick-ups all fail with ethanol involved. Fuel stabilizers can only deal with liquified water, not chemically bound water.Stick with ethanol-free gasoline. -Dick

 

[craigb93]

The solenoid is a problem and I have removed mine (742). That said, MOST of the solenoid problems come from using ethanol bearing fuel. Mine ran 20-years trouble-free until that stuff came on the market. Have only used ethanol free fuel for the last 10-years to remove that problem. Fuel pump diaphragms, brass carburetor fitments and fuel tank pick-ups all fail with ethanol involved. Fuel stabilizers can only deal with liquified water, not chemically bound water.Stick with ethanol-free gasoline. -Dick

I should mention that the octane rating of nearly any ethanol-free gasoline on the market today is high enough to preclude any dieseling, thus making the anti-dieseling solenoid redundant. so your machine is still safe from that problem without the solenoid. -Dick

 

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I should mention that the octane rating of nearly any ethanol-free gasoline on the market today is high enough to preclude any dieseling, thus making the anti-dieseling solenoid redundant. so your machine is still safe from that problem without the solenoid. -Dick

I am going to add a shut off valve close to the carburetor. When I am done with the machine, I will shut the fuel off and let it run out of fuel.

 

[spitzair]

I am going to add a shut off valve close to the carburetor. When I am done with the machine, I will shut the fuel off and let it run out of fuel.

You have what's called a KSG416 engine in your machine. It was used on 632, 642, 722, 732 and 742 Bobcat loaders and is also found in other brands of equipment. They are an industrial version of the Ford "Kent" engine that was used on the Ford Cortina and early Fiestas. Ignition and carburetor parts should all interchange as far as I know. The main differences are in the head I believe. I just fully overhauled one earlier this year and parts are still out there but you will have to invest a bit of time searching. Pegasus racing has a very knowledgeable guy there (can't remember his name just now) and I'm 100% he can help you get parts or at least point you in the right direction.

 

[spitzair]

You have what's called a KSG416 engine in your machine. It was used on 632, 642, 722, 732 and 742 Bobcat loaders and is also found in other brands of equipment. They are an industrial version of the Ford "Kent" engine that was used on the Ford Cortina and early Fiestas. Ignition and carburetor parts should all interchange as far as I know. The main differences are in the head I believe. I just fully overhauled one earlier this year and parts are still out there but you will have to invest a bit of time searching. Pegasus racing has a very knowledgeable guy there (can't remember his name just now) and I'm 100% he can help you get parts or at least point you in the right direction.

I forgot to add that my 732 doesn't have the carb solenoid either. I run mine mostly on 100LL avgas and it never diesels on me...

 

[Schifference]

I forgot to add that my 732 doesn't have the carb solenoid either. I run mine mostly on 100LL avgas and it never diesels on me...

When I tried to rebuild the carb, the new jet wouldn't screw in. I tried several times. The threads looked the same. I ended up just using the old one. So It has been raining and then I wasn't feeling well. The day I put the carburetor in I had a dead battery so I couldn't start it. I put a charge on it. Then yesterday I go out to start it and it still won't turn over. Don't you know that new battery disconnect I recently put on is finicky and doesn't work properly. I removed it and put the negative terminal directly back on the battery terminal. The Bobcat starts right up. I let it run awhile and shut it off and removed the cable from the battery. Today, I have work to do and want to use it. I go and start it so it can warm up. It fires right up, runs less than 10 minutes and shuts off and won't start. Simple solution. Out of fuel. Went to the gas station purchased a couple cans and 642 Runs very well.