2518 Carburetor Problem

Merlin2014 · #1 04-06-2019, 05:42 PM

I need everyone’s help with carburetor issues. Let me start by saying that I am not a mechanic and know nothing about carburetors. So, I have a 2185 and 2518 both with the CH18-S engine with Keihin 24 053 carburetor. I’m actually working with the 2518 mower but have tried both carburetors numerous times with very limited success. The first thing I did was remove and clean the fuel tank and replace all the fuel line and the filter before ever attempting to start the engine. The engine would not start so I pulled the carburetor and after watching several YouTube videos checked the solenoid which was stuck. I sprayed it with carb cleaner and eventually got it where it would operate properly but engine still would not start. I took the carb back off and opened it up. It was full of gunk so I sprayed it with cleaner and tried to clean out all the little passages and the bowl. I reinstalled it and after that it would run but not very well. I ordered a couple cheap rebuild kits off the internet and replaced the float needle valve, idle needle and spring, numerous o-rings, and the gasket. Reinstalled the carb and the engine would start and run but didn’t idle very well. It did run reasonably well and I made several circles around the yard with it but just wasn’t satisfied with the idle. So, I went back into the carb to see if maybe I missed some little something. Well, I’ve been back in that carb (and the carb off the 2185 which pretty much went through the same stages of rebuild) now numerous times and the engine runs worse all the time. With it’s original carb it will now only run for a few seconds at a time and with the carb off the 2185 it will run, though not very well, and that only with the choke mostly closed. I’ve taken them both back apart several more times now without any improvement. I’m clueless at this point and would be very appreciative of any help with this issue. Thanks,

Mike McKown · #2 04-06-2019, 07:37 PM

I would start with getting that fuel solenoid working loosey/goosey.

Some suggest cutting the pin off the solenoid to prevent these kind of problems. I've never seen the need after working on a dozen or so B/S and Kohler engines with this design feature.

CubDieselFan · #3 04-06-2019, 08:00 PM

I bet you are not getting it clean enough. Have they sat for an extended period of time, not being started?

ccpullin · #4 04-06-2019, 10:36 PM

The carburetors need more cleaning. Remove the carburetors and look at the bore from the bottom. You will see 5 very small holes on the side of the bore even with the throttle shaft/plate. Take a bread wrap twistie, pull the paper off of it, now you have a stainless steel wire small enough to clean out these very small passages. I usually make a bend in the wire and go up in there with needle nose pliers. Then take carb clean with the straw on it and blast those holes. It may take a couple of times. If one hole is plugged it will hunt, more than one and you have to choke it all the time and still runs bad.

Mike McKown · #5 04-07-2019, 07:28 AM

Thanks for that tip.

mickb72 · #6 04-07-2019, 09:32 AM

Do you know if your fuel pump is working right. I'm with CCPullin on cleaning those holes. Did you pull the slow jet and change those tiny o rings? Those degrade to mush and plug things up. Most cheap kits don't include those tiny o rings for the slow jet. Mike

Merlin2014 · #7 04-07-2019, 10:04 PM

I do appreciate everyone’s responses. The fuel pump does seem to be working properly though I suspect it did contribute to my problems. As I mentioned before I replaced the fuel line and filter before attempting to start the mower but I did not think to flush out the pump so I imagine that I pumped some trash right back into the carburetor early in my attempts to get the mower running. I did replace the o-rings on the slow jet and they were definitely disintegrated so I’m sure that helped. I will definitely pull the carburetor tomorrow evening and make sure the small openings in the bore are all open. Maybe that will finally fix my problem and I can move on to another part of this project. Thanks.

Merlin2014 · #8 04-08-2019, 08:51 PM

I went out this evening and removed the carb again. Separated the two sections of the body and tried to run a wire through all the little passages and the small ports in the lower part of the bore. There are three kind of in a cluster and one closer to the bottom of the bore. Put it back together and reinstalled it on the mower with no change. Mower will only run for about 5 seconds and only with the choke on. Oh well. I appreciate all the suggestions and support. I guess I’ll have to take it completely apart and soak it in solvent, blow out all the passages again put it back together and see what I have then. Thanks,

ol'George · #9 04-09-2019, 08:26 AM

Quote:

Originally Posted by Merlin2014

I went out this evening and removed the carb again. Separated the two sections of the body and tried to run a wire through all the little passages and the small ports in the lower part of the bore. There are three kind of in a cluster and one closer to the bottom of the bore. Put it back together and reinstalled it on the mower with no change. Mower will only run for about 5 seconds and only with the choke on. Oh well. I appreciate all the suggestions and support. I guess I’ll have to take it completely apart and soak it in solvent, blow out all the passages again put it back together and see what I have then. Thanks,

If it only runs for 5 seconds it just might be the bowl is not filling with fuel.
remove the needle valve and blow air back through it to dislodge any obstruction that might have gotten in the area between the needle seat and where the hose connection is, I have seen it numerous times when someone replaces a fuel line.
You obviously have a fuel delivery issue.
Is the float dropping sufficiently to get fuel in the bowl?

Merlin2014 · #10 04-10-2019, 07:53 PM

I took the carburetor back off my mower and totally disassembled it. Ran a small wire through all the passages, sprayed everything out with carb cleaner, and then blew it all out with the air hose. Reinstalled the carburetor and it ran for about five seconds then died out. I sat there on the seat for a minute just trying to think through my situation. I then turned the key on again and it again fired and ran for just a few seconds and died. I sat there a little longer and then turned the key on again and suddenly the light bulb came on. I wasn’t hearing the solenoid click. I got my meter and sure enough there was no voltage to the solenoid. I took the ignition switch apart, cleaned the contacts, reassembled it and checked for voltage which I then had. So I reconnected the solenoid wire and turned the key. I heard the click so I started the engine. It ran well so I took the mower for a quick tour around the yard. I would really like to write here telling all about how I did some masterful job on the carb this time and had really got it working perfectly but the truth is that the solenoid had stopped operating do to a fault in the ignition switch. Go figure! Anyway, I do appreciate everyone’s assistance with this issue. I definitely had carburetor issues which I did get repaired with the help of everyone here I just failed to realize that at some point that solenoid had stopped working. Thanks to everyone!