Injector Pump on 743B

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chevyman

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I bought a 743B about 2 months ago and it had a little bit of fuel on top of injector pump. I ordered new "o" rings. My question is could this cause my 743 to lack in power? I drove bigger equipment years ago so I'm not acquainted with something of this size. Tonight for instance I was out moving a little bit of melting snow and under that snow is mud cause I finished building my new home late December and it wants to stall when going through thick mud ,is this normal?. Engine starts perfectly and exhaust fumes are OK.
 

Tazza

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It depends on where the fuel is coming from, i have had leaks coming from the metal tube lines that go from the pump to the injectors, which just needed the lines twisting and tightning. I am un-sure where the fuel is coming from on yours.
If there is only a small leak, i would say this will not affect your engine performance. Was the machine warm when you were moving your snow? if not, your oil would be a little thick causing the engine to work harder to move it around. The 743's only have 36HP, so there really isn't THAT much power there, but with your revs up, moving slowly it shouldn't even attempt to stall.
Remember that you will get more power from your machine moving slowly when cutting than if you plow in at full speed. Its also normal for it to blow a bit of smoke when under a hefty load.
 

Blaine

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It depends on where the fuel is coming from, i have had leaks coming from the metal tube lines that go from the pump to the injectors, which just needed the lines twisting and tightning. I am un-sure where the fuel is coming from on yours.
If there is only a small leak, i would say this will not affect your engine performance. Was the machine warm when you were moving your snow? if not, your oil would be a little thick causing the engine to work harder to move it around. The 743's only have 36HP, so there really isn't THAT much power there, but with your revs up, moving slowly it shouldn't even attempt to stall.
Remember that you will get more power from your machine moving slowly when cutting than if you plow in at full speed. Its also normal for it to blow a bit of smoke when under a hefty load.
I would think that it should be able to spin the tires before the motor boggs. I don't know if I have ever driven a 743 though. They are a little smaller and as such their abilities will be different. As far as the fuel leak, depending on where it is leaking from it may cause a significant loss of power. If it is one of the injector lines, you would loose power. If it is just the return line, it really wouldn't affect anything. I personally would take it to the injection shop and have them flow check it for me. If the flow is low, that would cause a loss of power.
 

chevyman

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I would think that it should be able to spin the tires before the motor boggs. I don't know if I have ever driven a 743 though. They are a little smaller and as such their abilities will be different. As far as the fuel leak, depending on where it is leaking from it may cause a significant loss of power. If it is one of the injector lines, you would loose power. If it is just the return line, it really wouldn't affect anything. I personally would take it to the injection shop and have them flow check it for me. If the flow is low, that would cause a loss of power.
Monday evening I will be checking where my fuel leak is and also change "o" ring on top of injector pump. So far fuel lines to injector seem fine. So i can Loose power, thats what I thought. As far as spinning tires in mud..it wont the motor will bogg first. Thanks Tazza and Blaine. Will keep you posted.
 

Tazza

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Monday evening I will be checking where my fuel leak is and also change "o" ring on top of injector pump. So far fuel lines to injector seem fine. So i can Loose power, thats what I thought. As far as spinning tires in mud..it wont the motor will bogg first. Thanks Tazza and Blaine. Will keep you posted.
It could also be engine wear, you can check for blow-by by feeling how much air comes out of the breether tube. On a *good* engine, there should be very little coming out, i have one that puffs alot out, but still has pleanty of power.
The other thing you could look at is your valve clearance and do a compression test. If its an injection problem, you should see a fair amount of smoke from the spray pattern being wrong causing fuel to remain un-burnt..
Before you go off and get your injectors and pump repaired, i would check your valve clearance, then do a compression test. You should get 400-450PSI on a good engine, i was told 300-350 is still acceptable for home use. If your compression is good, it would be worth getting your injection system done. If it has low compression, you may be wasting your time getting the injection system done.
Lut us know what you find out.
Just my 2c worth
 

chevyman

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It could also be engine wear, you can check for blow-by by feeling how much air comes out of the breether tube. On a *good* engine, there should be very little coming out, i have one that puffs alot out, but still has pleanty of power.
The other thing you could look at is your valve clearance and do a compression test. If its an injection problem, you should see a fair amount of smoke from the spray pattern being wrong causing fuel to remain un-burnt..
Before you go off and get your injectors and pump repaired, i would check your valve clearance, then do a compression test. You should get 400-450PSI on a good engine, i was told 300-350 is still acceptable for home use. If your compression is good, it would be worth getting your injection system done. If it has low compression, you may be wasting your time getting the injection system done.
Lut us know what you find out.
Just my 2c worth
Tazza thanks again!! I will make sure to check compression and blow-by. A friend of mine will help me next week to check it all out, I will let you know.
 

chevyman

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Tazza thanks again!! I will make sure to check compression and blow-by. A friend of mine will help me next week to check it all out, I will let you know.
To all: I changed the "o" rings on top, found one that was defective thats were my fuel leak was from and all seems OK. I drove it a bit around and found a 25% increase in power and now can spin my tires and do 360's without having engine wanting to stall. Tazza I have a question for you! I checked blow by like you said and found that if i keep my fingers 1 inch away i can feel the air coming from tub, is this acceptable? Thanks in advance.
 

Tazza

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To all: I changed the "o" rings on top, found one that was defective thats were my fuel leak was from and all seems OK. I drove it a bit around and found a 25% increase in power and now can spin my tires and do 360's without having engine wanting to stall. Tazza I have a question for you! I checked blow by like you said and found that if i keep my fingers 1 inch away i can feel the air coming from tub, is this acceptable? Thanks in advance.
Its hard to say, as what you will be feeling is the air blowing out not when it is drawn back in. Try holding your finger over the tube lightly while the engine is running then let it go. Don't hold it too tight or you can blow your seals out if you build up too much pressure.
If its running well now, without stalling i would not worry about it. You did say its easy to start. If its still easy to start, your compression must still be good.
The 743 that i have with lost of blow-by is so bad, that when its under a good load, it blows lots of smoke out the breether tube.
If you really wanted to know the state of your engine you will need to do a compression test.
 

skidsteer.ca

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Its hard to say, as what you will be feeling is the air blowing out not when it is drawn back in. Try holding your finger over the tube lightly while the engine is running then let it go. Don't hold it too tight or you can blow your seals out if you build up too much pressure.
If its running well now, without stalling i would not worry about it. You did say its easy to start. If its still easy to start, your compression must still be good.
The 743 that i have with lost of blow-by is so bad, that when its under a good load, it blows lots of smoke out the breether tube.
If you really wanted to know the state of your engine you will need to do a compression test.
An engine is a "air pump" It draws air in, the cylinders compress it, then after the power stroke it is expelled out the exhaust. Blow by or pressure in the crankcase, (air coming out dipstick hole, or oil fill hole, or usually crank case vent tube) is air that has leaked passed the piston in the cylinder (s) and is a sign of piston ring wear or a poor seal between the piston and cylinder(s)------------------------------------------------------------------------------------------------------------------------------------------------- Some blowby is normal even for a "just broken in" engine, (new engines may have more until the piston rings seat themselves) As an engine wears, hopefully over several thousand hours, blowby gets worse, until eventualy compression is to low to fire the cylinder.-(note cylinder may missfire for numerous other reasons) and the engine miss fires. ----------------------------------------------------------------------------------------------------------------------------If one cylinder is worn this bad, you will see and feel a vary noticable PUFF PUFF of air coming out the breather tube. If all cylinders are wore badly, the volume of air coming out the breather tube can be @ 20 % of the volume of exhaust gases. (in my experince) Usually by the time its this bad, the blowby will be carrying crankcase oil out with it and the engine will look "messy" as oil may be leaking out crankshaft seals, or oilpan and valve cover gaskets. (from the bressure trying to escape) The only repair for blowby is to rebuild the engine. (Bore it out, new pistons and rings) Hopefully, you get many thousand hours from your engine, and "the fog" coming from your crankcase is minimal. Ken
 
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