743 will not start

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Very Newbie

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Dec 4, 2007
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Hi everyone, I have a 743 that was running fine and when I went to shut it off it died before I could stop it. I didn't think much of it but the next day when I tried to start it, it would crank just fine but wouldn't fire. It has plenty of fuel in it so that's not the problem. I replaced the fuel filter and air filter and when doing so found a crack it the fuel line by the primer bulb. I fixed the line and it still will not start. When I squeeze the primer bulb to fill the fuel filter I can't get it to siphon. Any ideas? Thanks in advance.
 

perry

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Aug 22, 2006
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From my experience, primer bulbs go bad, pick one up from NAPA for about 8 bucks. also try blowing in the fuel line (from the tank) just to make sure the pickup is not clogged.
 
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V

Very Newbie

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From my experience, primer bulbs go bad, pick one up from NAPA for about 8 bucks. also try blowing in the fuel line (from the tank) just to make sure the pickup is not clogged.
Thanks, I was planning to get a new primer bulb on the way home from work today and I'll blow out the line when I put it on. I'll be back here tomorrow if this doesn't work looking for more clues.
 

Tazza

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Thanks, I was planning to get a new primer bulb on the way home from work today and I'll blow out the line when I put it on. I'll be back here tomorrow if this doesn't work looking for more clues.
I found that without a one way valve on the pickup tupe in the fuel tank you can have this sort of problem. I found removing the fuel line to the lift pump and squeezing the primer bulb then when hold your finger over the fuel line to prevent air from being drawn back. Let the bulb expand then repeat a few times till you get a decent flow. Re-attach the fuel line then open the valve on the injector pump and squeeze the bulb a few more times till it feels like there is no more air. Close the valve and you *should* be rite.
 

richard

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Dec 21, 2005
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I found that without a one way valve on the pickup tupe in the fuel tank you can have this sort of problem. I found removing the fuel line to the lift pump and squeezing the primer bulb then when hold your finger over the fuel line to prevent air from being drawn back. Let the bulb expand then repeat a few times till you get a decent flow. Re-attach the fuel line then open the valve on the injector pump and squeeze the bulb a few more times till it feels like there is no more air. Close the valve and you *should* be rite.
I had this same problem with my 743B. After changing the bulb, fuel pump, filter, etc. I found the problem. The fuel pickup tube inside the fuel tank had become rotten and had broken off inside the fuel tank. So even though the tank was full of fuel...the tube was broken off above the fuel level and was just sucking air. Try this.....blow air into the fuel line going into the tank.....if you hear fuel gurgling then your ok......if you only hear air flowing through then apparently your tube has broken off too.
Hope this helps.
 
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V

Very Newbie

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I had this same problem with my 743B. After changing the bulb, fuel pump, filter, etc. I found the problem. The fuel pickup tube inside the fuel tank had become rotten and had broken off inside the fuel tank. So even though the tank was full of fuel...the tube was broken off above the fuel level and was just sucking air. Try this.....blow air into the fuel line going into the tank.....if you hear fuel gurgling then your ok......if you only hear air flowing through then apparently your tube has broken off too.
Hope this helps.
6:30am here in Wichita Kansas and I'm happy to report that I got her running again. After replacing the fuel line and primer bulb I got nothing. I pulled the pickup tube out and it had broken off about 8 inches from the top. I had previously looked inside the tank with a flashlight and I could see the pickup tube. It looked like it was fine but actually it was just below the surface of the fuel level. The tank was about half full and if I would have added more fuel it would have ran fine until the fuel ran down to the same level. I replaced the tube with new fuel line, pumped the bulb until I had good pressure and she fired right up! It took about ten minutes running at full throttle until I could get all of the air out of the system and then she ran like new. I put her to work hauling old concrete a quarter mile down the road to a neighbors creek that is washing out and she loved it! Thanks to all who replied and I did see that the last reply had the same problem I did. I'm glad that we both figured it out and got back to work!
 

Tazza

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6:30am here in Wichita Kansas and I'm happy to report that I got her running again. After replacing the fuel line and primer bulb I got nothing. I pulled the pickup tube out and it had broken off about 8 inches from the top. I had previously looked inside the tank with a flashlight and I could see the pickup tube. It looked like it was fine but actually it was just below the surface of the fuel level. The tank was about half full and if I would have added more fuel it would have ran fine until the fuel ran down to the same level. I replaced the tube with new fuel line, pumped the bulb until I had good pressure and she fired right up! It took about ten minutes running at full throttle until I could get all of the air out of the system and then she ran like new. I put her to work hauling old concrete a quarter mile down the road to a neighbors creek that is washing out and she loved it! Thanks to all who replied and I did see that the last reply had the same problem I did. I'm glad that we both figured it out and got back to work!
Glad it was an easy fix. If you can, get the end that fell off in the tank out and install the one way valve and screen to the end of the new pickup tube. The one way valve helps prevent problems with loss of prime. If you can't get it out, its no big deal. If you haven't already put it on the new pickup tube its not a real problem, just keep the tank full and ensure the valve on the injector pump is kept closed and you shouldn't have a problem.
Removing air from the system should have been pretty fast, open the valve on the pump and squeeze till you can't hear air and it feels firm. Then start and it should clear up within seconds, not 10 minutes!. Ensure the valve on the pump is off, unless you didn't open this to bled the system then i understand why it took a while to get the air out.
 

goferbroke

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Dec 9, 2007
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Glad it was an easy fix. If you can, get the end that fell off in the tank out and install the one way valve and screen to the end of the new pickup tube. The one way valve helps prevent problems with loss of prime. If you can't get it out, its no big deal. If you haven't already put it on the new pickup tube its not a real problem, just keep the tank full and ensure the valve on the injector pump is kept closed and you shouldn't have a problem.
Removing air from the system should have been pretty fast, open the valve on the pump and squeeze till you can't hear air and it feels firm. Then start and it should clear up within seconds, not 10 minutes!. Ensure the valve on the pump is off, unless you didn't open this to bled the system then i understand why it took a while to get the air out.
The pickup tube is attached to an L-Shaped connector at the top of the tank, and the L-Shaped connector runs through a rubber grommet. Does the rubber grommet have to be pulled, or is is simply a matter of tugging on the L-Shaped connector until it comes out? What's the procedure?
 

Tazza

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The pickup tube is attached to an L-Shaped connector at the top of the tank, and the L-Shaped connector runs through a rubber grommet. Does the rubber grommet have to be pulled, or is is simply a matter of tugging on the L-Shaped connector until it comes out? What's the procedure?
The elbow and grommet have to come out to gain access to the pickup tube.
 

Fishfiles

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Feb 8, 2007
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When i did mine it was a nightmare too! they sure aren't made to go back in easily.
It really helps to get a new grommet , I don't use the soft tubing any more and use hard plastic tubing which the local dealer sells cut to the correct length for each application , I don't put a screen on the end either , put the grommet into the tank then slide the tubing down the hole , get the nipple of the 90 degree fitting the tube is connected to started in the grommet , then use a hammer handle or large screw driver and push the fitting into the grommet , some models are harder than others , to get them out a door trim tool on a 43 series , the ones with tanks under the engine I bent a trim tool in the shape of a heel bar it also works getting the tank and chain case plugs out
 
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