# 725r quits after 30 secs



## pbroussard (May 12, 2005)

I've had this ryobi 725r weedeater for 5 years or so, with light use. This year, troubles started with fuel line cracking, then primer bulb cracking right after that. No problem so far, but then it started cutting out when it got hot. I figured I couldn't go wrong with getting a Zama gasket kit to redo the carb, but still had the problem. Finally figured out the new fuel line was a bit long, and curved right up to the cylynder wall, and was boiling the fuel, causing vapor lock.

Now I had it running fine, but it was leaking gas from the throat when stored, and the starter was skipping. Off to the parts store for a new needle valve assembly and used starter gear. Now it starts and runs for maybe 30 seconds, and dies, runs out of gas. I do notice that the needle valve doesn't seem to want to seat all the way down. It's puzzling me, since if it's not seating, then it should be getting fuel, and even leaking out of the throat when stored, shouldn't it?

Thanks for any insight anyone might have. Wife tells me to get a new one, but after all this work, I can't let it beat me!

Paul


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## bugman (Aug 12, 2004)

could be getting to much fuel.. though the carb may need a good rebuild, not just gaskets but a new diapragm, etc.


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## pbroussard (May 12, 2005)

Thanks, bugman! I neglected to mention that the gasket kit contained everything except the float needle assembly, including new diaphram. The thing runs well and just dies, no sputtering, it just quits..... if that helps any. I did put on reading glasses, cleaned and examined the needle valve and hole, they seemed to be spotless, really don't see how the needle is not closing all the way by itself, without the diaphram installed. Doesn't seem to be binding at all.

Paul


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## bugman (Aug 12, 2004)

there should be a little spring right there, that may need replacing as well.


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## hankster (Jan 1, 1998)

Also check to make sure the cylinder bolts are tight. A lot of this stuff is hard to diagnose on-line without hearing (or feelings) what it is doing. Just the sound of the engine or feel when pulling the rope can tell you a lot... hard to do that on-line


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## pbroussard (May 12, 2005)

Thanks for the replies. With this Zama carb, with the diaphram cover off, looking at the float needle assembly, the needle should be fully seated (closed), correct? I remove the hold down screw, and the spring extends fully, so I assume the spring is ok. The kit does not include a new spring, at least the one I got didn't. When I press down on the needle head, it takes a slight force to get it to seat all the way down, so even though I can't see any binding, it apparently is. I do have Zama's .pdf files for reference with all the diagrams, everything seems to be correct in assembly.

Oh, btw, the fuel line should go to the bottom of the carb, and the primer bulb line should go to the top of the carb, correct? This is a shroud mounted primer bulb, not one mounted atop the diaphram cover. I'm reasonably sure I replaced the fuel line and primer bulb correctly, but doesn't hurt to double check...

edit- I just looked at it again, I think I may have the fuel lines mixed up, there's a inlet right in a row with the idle/high needles on top of the carb, and one on the bottom of the carb. Seems to me the fuel line should go at the top, and the line from the primer bulb should go to the bottom inlet... Probably why I had the earlier problem of fuel line too close to cylinder, causing fuel boil, routing was incorrect.

Paul


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## hankster (Jan 1, 1998)

Unless I have one in front of me I can never remember if a primer setup is a sucker or a pusher. 

Some primers suck through the carb which means the line (with the fiter) from the tank goes to the inlet side of the carb, the carb to the primer and the primer back to the tank.

With the pushers the line from the tank goes to the primer and then from the primer to the inlet side of the carb and then back to the tank.

Some day I have to write down what manufacturers do what.


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## bugman (Aug 12, 2004)

i think those are in-line primers on them all now.


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## pbroussard (May 12, 2005)

THanks for the replies. Had to leave town for the entire weekend to go down to New Orleans and fix the wife's car. SHe impaled the Intepid's fascia on a truck trailer hitch, bending the power steering cooling tube, then the trans cooler, condenser, radiator, then pushing the fan shroud into the serpentine belt assembly. Managed to straighten it all out , and bought a new fan shroud.

I did swap the fuel lines in the Ryobi, the primer bulb will pump once, then build pressure, so apparently I had the lines run correctly to begin with. Still, I might drop by a Home Depot and take a look at one, to see how the lines are run to make sure.

Paul


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## bugman (Aug 12, 2004)

couldn't hurt, they will have a show model out for you to look at.


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## hankster (Jan 1, 1998)

I can take a look at one tomorrow and let you know how they go.


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## pbroussard (May 12, 2005)

Appreciate it. Didn't get a chance to stop by Home Depot, and it looks like I'll be working out of town the rest of the week...

Paul


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## hankster (Jan 1, 1998)

Doh... forgot to look... will tomorrow.


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## hankster (Jan 1, 1998)

The lines should go from the filter in the tank to the inlet side of the carb. Then from the carb to the primer and then the primer back to the tank.


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## pbroussard (May 12, 2005)

Thanks once again, Hank. I did stop by Home Depot, but the models used had a primer bulb built onto the diaphram. So I take it the inlet side is on top of the (installed) carb, on the side of the diaphram cover, and the outlet on the bottom side opposite the diaphram? I'll give it a whirl this afternoon if I don't bake out there... ;-)

Paul


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## hankster (Jan 1, 1998)

Attached is a picture of how the lines run on a new one.


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## shakeyguY (Jun 3, 2007)

It may be 2 years later but this thread just fixed my Ryobe problem. After having it run bad I cleaned the carb but them it started slowly draining tank. Somehow I messed up the fuel line thinking the pump was in the tank supply route and you guys put me onto that.
Please let me summarize:
Fuel filter "in tank" to top of carb.
Carb lower to pump in
Pump out to tank return.
Runs great-after buying a replacement, unneeded, carb and having same problem.

Thanks all
SG


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