My motor wont stay running...

[scrit9mm]

I purchased this 25r73 a couple of weeks ago. I rebuilt the carb, put new plugs in, rewired the kill switch, and replaced the screen filter, gasket, and cap on the fuel pump.

I am attempting to crank it tonight, it will crank and run for about 2-3 seconds every 8th pull or so. I have screwed in the low speed needle all the way and backed it out one turn. There is a little gas that ran out of the front of the carb. I closed the choke and pulled it a few times with nothing. I open the choke and pull it 4-5 times and it will crank then die. Then I will pull it and it will backfire on the second pull.

Can anyone help me troubleshoot?

 

[scrit9mm]

Re: My motor wont stay running...

ok, so i unscrewed the low speed needle about 5 times, it cranked and was running really fast, I attempted to dial the needle in some and it died. this happened twice. also there was a lot of smoke? I guess that is typical for a engine that hasnt been cranked for 10+ years?

 

[Will Bark]

Re: My motor wont stay running...

Did you take the welch plug out of the top of the carb and blow carb cleaner and air thru the three little holes in the idle circuit?

 

[AlTn]

Re: My motor wont stay running...

did you remove the main jet and clean it thoroughly as well as the area behind it?...remove the nozzle and clean it ?< if it looks sorta questionable as far as removal goes just clean it in place>..did it run, though poorly, when you purchased it?

 

[scrit9mm]

Re: My motor wont stay running...

Did you take the welch plug out of the top of the carb and blow carb cleaner and air thru the three little holes in the idle circuit?

I suppose the welch plug is the pressed in plug on the top of the carb. If that is correct then no, I did not take any plugs out of the carb. I did clean every hole and surface in the carb with carb cleaner then blew it out with compressed air.

 

[scrit9mm]

Re: My motor wont stay running...

did you remove the main jet and clean it thoroughly as well as the area behind it?...remove the nozzle and clean it ?< if it looks sorta questionable as far as removal goes just clean it in place>..did it run, though poorly, when you purchased it?

Main jet? Is that the high speed needle? If so then I cleaned the surface around it as well as replaced the needle and the screw that the needle sits in that is under the float.

It did not run when I purchased it.

 

[scrit9mm]

Re: My motor wont stay running...

So, my co-worker and I were discussing these issues. We went through every situation. I failed to mention the fuel tank leaks under the plate where the fuel line hooks up. When I pump the primer bulb I can hear fuel going into the carb and air seaping out of the gas tank, then there is fuel on the top of the tank where it leaked out. So this is probably the issue. I pull the cord a few times after I prime the bulb, the motor starts and runs at a high rpm then dies. I take that to mean that the motor runs until it uses up the fuel in the line and in the carb and because there is no pressure created in the line because of the leaking tank there is no more fuel therefore it dies. Does this make sense to anyone.

My next step is to replace all fuel lines in the motor and get a new tank.

 

[AlTn]

Re: My motor wont stay running...

so we can get on the same page..marineengine.com has diagrams of your motor including part no.s and names...the main jet and orfice plug are the same thing, if you use a straight slot screwdriver to remove it make certain it fits into the slot tightly as you don't want to damage the ears of the plug..part of the confusion is in "I rebuilt the carb" means different things to different people. In a manual you would be instructed to pop that core plug and clean under it, remove the low speed mixture needle and inspect it for grooves, pitting, bent point, etc, clean the bearing area it screws into and remove and replace the packing. Float level is set with the carb inverted and the float parallel with the carb body.
Certainly any air leaks will affect fuel delivery. However, with just the carb bowl full, your engine should run 15 to 20 secs. possibly longer at idle.

 

[scrit9mm]

Re: My motor wont stay running...

That's just it. I think because I had the low speed needle unscrewed so much it ran at such a high rpm that it would run all of the fuel out quickly, 5 seconds or so. I attempted to remove the "main jet" but I was afraid that I would damage it.

 

[AlTn]

Re: My motor wont stay running...

k..main jet in place cleaning...try twisting a couple of copper stands together and gently twist them into and out of that orfice < contra recommended as you really don't want to enlarge that jet diameter as it's a precise metering piece, but it really does need to be super clean>...that you need the idle mixture needle that far out to get it to start means you're gonna have to revisit the idle circuits as well...when you get the fuel lines replaced and tight you'll have a better gauge of what's needed fuel delivery wise.
FWIW...I've found that a clear vinyl fuel line from the fuel pump to the carb makes diagnosing issues in the fuel delivery much easier as that line should remain full <no air bubbles> when the motor is running