help with 742b

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jtk19

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Mar 16, 2008
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i have a 742b bobcat with a mitishibi engine. i can get spark to the points but not out of the cap. i have replace a rotor,condencer,cap. i need help because i cant think of another answer to why it wont start. it turns over fine but with out that spark out of the cap i cant get fire. anyone that can help i would be grateful. jeff
 

Tazza

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Could it be the coil is bad?
The points only spark when they open and close the circuit to the coil.
 

jerry

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i replaced the coil too. thanks
crank the engine over with the cap off to ensure that the rotor is actually turning, if it is and everything else is good there has to be a grounded wire or cracked insulation somewhere in there. Have the coil checked if it is not new. A lot of times there will be a short where the wire passes through the wall of the distributor and is connected inside. let us know how things go.
 
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jtk19

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crank the engine over with the cap off to ensure that the rotor is actually turning, if it is and everything else is good there has to be a grounded wire or cracked insulation somewhere in there. Have the coil checked if it is not new. A lot of times there will be a short where the wire passes through the wall of the distributor and is connected inside. let us know how things go.
ok guys, im half way home. i got spark to the plugs now i replace the coil wire from the coil to the cap and grounded the condenser better and now i have spark to the plugs. there is the good news but now the bad, i cranked it over about 10-15 time to try to start and tried to use a little starting fluid but it didnt start and my battery witch i just charge last night died. and the negative cable was hot as hell when i went to pull the battery, any idea where i go from here. thanks to everyone with your tips jeff
 

jerry

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ok guys, im half way home. i got spark to the plugs now i replace the coil wire from the coil to the cap and grounded the condenser better and now i have spark to the plugs. there is the good news but now the bad, i cranked it over about 10-15 time to try to start and tried to use a little starting fluid but it didnt start and my battery witch i just charge last night died. and the negative cable was hot as hell when i went to pull the battery, any idea where i go from here. thanks to everyone with your tips jeff
I think clean up all battery connections and charge it up, take out the plugs and squirt a squirt of oil in each cylinder. you may have washed all of the oil down with the starting fluid. spin it over a few times with the plugs out clean the plugs and reinstall. when you have the plugs out check your timing mark on the damper pulley to make sure your rotor is on #1 when the timing mark is on tdc and #1 piston is on the top of compression stroke, also check your firing order, it is not hard to get wires mixed up. if timing is basically right and everything else is take off the air inlet to make sure the choke is completely closing and try again but don't overheat your starter. at this point if the plugs do not get wet could even be ice in the gas line or other fuel supply problem.
 

Tazza

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I think clean up all battery connections and charge it up, take out the plugs and squirt a squirt of oil in each cylinder. you may have washed all of the oil down with the starting fluid. spin it over a few times with the plugs out clean the plugs and reinstall. when you have the plugs out check your timing mark on the damper pulley to make sure your rotor is on #1 when the timing mark is on tdc and #1 piston is on the top of compression stroke, also check your firing order, it is not hard to get wires mixed up. if timing is basically right and everything else is take off the air inlet to make sure the choke is completely closing and try again but don't overheat your starter. at this point if the plugs do not get wet could even be ice in the gas line or other fuel supply problem.
Its normal for your starter cables to get warm when cranking a bit.
I would also check timing, even with starting fluid it should at least kick over a little so you know there is life. If it still fails, you may want to check compression.
 
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jtk19

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Its normal for your starter cables to get warm when cranking a bit.
I would also check timing, even with starting fluid it should at least kick over a little so you know there is life. If it still fails, you may want to check compression.
i think my fuel pump is not working pull top off carb and very little gas. so i pull the fuel line to the pump and there was not a trickel in the line does any one know where i can get a pump or how to repair it. and do the fuel shut off valve go bad that often do you guys think i should bypass that valve thank jeff
 

jerry

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i think my fuel pump is not working pull top off carb and very little gas. so i pull the fuel line to the pump and there was not a trickel in the line does any one know where i can get a pump or how to repair it. and do the fuel shut off valve go bad that often do you guys think i should bypass that valve thank jeff
On my 632 there is a electric soleniod valve in the fuel line, maybe you have this and it is not opening?It is easy to find on the line.
 
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jtk19

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On my 632 there is a electric soleniod valve in the fuel line, maybe you have this and it is not opening?It is easy to find on the line.
i traced the line it comes out of the gas tank then it goes to a needle valve then out of the valve it goes to the fuel pump and from the pump up to the carb. i dont think there is a soleniod that im missing anywhere. thanks for you reply. the fuel pump is mechanical not electrical. do they go bad that often because its a simple design or do you guys think i should be looking at something else than the fuel pump thanks jeff
 

Tazza

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i traced the line it comes out of the gas tank then it goes to a needle valve then out of the valve it goes to the fuel pump and from the pump up to the carb. i dont think there is a soleniod that im missing anywhere. thanks for you reply. the fuel pump is mechanical not electrical. do they go bad that often because its a simple design or do you guys think i should be looking at something else than the fuel pump thanks jeff
If it was me, i'd pull the fuel hose to the carb off and crank the engine to see if you get any fuel pressure, it should squirt a bit of fuel out. Another way to ensure its not a fuel line problem is to see if you can blow air through the inlet line from the fuel tank. This line should be clear, not sure if it has a one way valve though. Even if you setup a fuel can behind the machine and hook it direct to the fuel pump and see what you get?
 

tsanders

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If it was me, i'd pull the fuel hose to the carb off and crank the engine to see if you get any fuel pressure, it should squirt a bit of fuel out. Another way to ensure its not a fuel line problem is to see if you can blow air through the inlet line from the fuel tank. This line should be clear, not sure if it has a one way valve though. Even if you setup a fuel can behind the machine and hook it direct to the fuel pump and see what you get?
tazza is right about checking for fuel but be very careful that you dont have anything sparking or you could have a fire on your hands. GOOD LUCK
 
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jtk19

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tazza is right about checking for fuel but be very careful that you dont have anything sparking or you could have a fire on your hands. GOOD LUCK
thanks to all, for your help and advise, i got it running it was a fuel line problem the needle valve got clogged and after i pull the line and clear it, it started right up. i used it today and i forgot how strong that machine is. but i got to throw in a question in here, after i shut it off i can swear i hear the gas getting backfeed, i know that isnt normal any idea's thank to everyone for all your help and advise jeff
 

sterlclan

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thanks to all, for your help and advise, i got it running it was a fuel line problem the needle valve got clogged and after i pull the line and clear it, it started right up. i used it today and i forgot how strong that machine is. but i got to throw in a question in here, after i shut it off i can swear i hear the gas getting backfeed, i know that isnt normal any idea's thank to everyone for all your help and advise jeff
bubbling sound? if so it could be gas boiling in the carb make sure all the air vents in the rad. and fan are clean so it doesn't make too much heat if the timing is off it could cause the same thing....Jeff
 
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