Bought a 1200 QL, Now its carb Issue!

[riflemann]

I got EVERYTHING squared away on this dandy new used QL 1200. Starter parts missing, advice and exploded view and it, too got fixed. So today I put starter back on and in cranks right up! It ran for about 30 seconds and quit....like you turned off the key switch. Couldn't get it to do anything. Checked spark, it was good. Fuel to the carb was good. Fed gas directly into carb ran for 4 seconds and quit. That's all I can get it to do. Pulled the carb off, pulled the bowl off, it looks clean. pulled main needle up out of carb, cleaned with carb cleaner, blew thru it and it appears clean. Unthreaded fast idle adjustment screw, cleaned. Put is all back together, put fuel directly into carb and it runs 5 seconds and quits!

Help!

[riflemann]

When I bought the tractor a couple of weeks ago, it started and ran fine. So I pulled the air cleaner off and its mounting plate and sprayed the HECK out of the exterior of the carb with spray carb cleaner and sprayed into the inside, too. Poured some Techron in the gas tank, too.

Did I dislodge some old gunk and grit and it is blocking up the carb?

[J-Mech]

Well.... Either your losing fuel, or spark. You tell us which. We aren't there, so your gonna have to keep testing. Basically all you gave us is, it won't run.

"Spraying the heck" out of the outside of the carb, or down it's throat does nothing. If you think it's not getting fuel, verify the carb is getting fuel first, then pull and disassemble it.

[riflemann]

I verified spark with electrical tester and verified fuel to carb by disconnecting fuel line at carb. Removed float bowl and confirmed fuel coming into it by turning fuel shutoff at tank. With fuel at tank on, carb bowl removed, could stop and start fuel coming thru by moving float up and down.

I am stumped. Thanks for your reply.

[sawdustdad]

If it runs for a few seconds when you put gas directly in the carb but won't keep running otherwise, then a carb rebuild is in your future. Remove and completely clean the carb, jets, passages, etc.

Reassemble, reset adjustment screws per manual. Run, put under load, and final adjust the carb.

How are you verifying spark? Describe in detail. I remove the plug and hold the threads against a head bolt while cranking. You said you used an electrical tester?

[riflemann]

I have an older Automotive/electric voltmeter type tester. it has a test mode on it when the spark plug wire gets a charge a light on the tester lights up. I have not seen an spark problem that occurs a few seconds after engine runs then quits, but I am no expert at small engine troubleshooting.

Are those cheapie China carburetors any good? it seems maybe just slap one of those on and adjust and go. I tried rebuilding a carb on another one of my 1200's a few years ago without success.

I could swap out one off one of my other 1200's for a little test, too. might do that today.

[J-Mech]

Originally Posted by riflemann

I have not seen an spark problem that occurs a few seconds after engine runs then quits, but I am no expert at small engine troubleshooting.

If you've never seen spark stop.... even shortly after the engine starts, then you haven't done much mechanicing at all.

Originally Posted by riflemann

Are those cheapie China carburetors any good? it seems maybe just slap one of those on and adjust and go. I tried rebuilding a carb on another one of my 1200's a few years ago without success.

Some are. But really man.... you can't take a bowl off a carb, pull the 3 screws out, clean it up and put it back together? It's pretty easy. The hard part is making sure all the passages are clean, and that is a breeze. I don't understand why people struggle with this. As far as carburetors go, they don't get any easier.

Originally Posted by riflemann

I could swap out one off one of my other 1200's for a little test, too. might do that today.

I suppose you could if you want to go through all the trouble. Easier to just fix the other one.



I'm betting your losing spark. If it can get enough fuel to fire up, then it should run for at least as long as it takes to run the bowl dry. I could be a fuel issue..... but your going to have to diagnose that. We can't see your engine. We can only suggest where you need to look.

[riflemann]

So how do it lose spark after running for 5 seconds? What would suddenly cause that? The tractor ran fine 3 days ago. I will recheck spark this morning.

[olds45512]

Originally Posted by riflemann

So how do it lose spark after running for 5 seconds? What would suddenly cause that? The tractor ran fine 3 days ago. I will recheck spark this morning.

Make sure all the electrical connections are clean and tight and check the wire coming out of the condenser real good, I had one that was broken right where it went into the condenser and it would do the same thing yours is.

[riflemann]

Swapped carb with one of the other QL1200's I own. Started right up. Took 15 minutes to perform swap. Giving this 1200 to one of my sons, he has a spare carb of his own he will put on it.

This 1200 is done and ready to mow. I paid $275 for it. New plug. air cleaner and starter motor spring, some minor adjustments.....you gotta love Cubs!!!

Thanks for all the replies.