flooding tecumseh single

[38racing]

ov490ea. Has the plastic bowl carb.Just bringing the mower out for first use. Normally when I stored it I would have shut off the fuel and run until bowl was empty. I put the battery in and it fired right up but while backing it out it stopped. I could only get it to fire again with injected carb cleaner. It has gravity height tank but has fuel pump. I checked gas supply was going all the way to carb. Also pulled and verified backfire solenoid. Then I tapped float bowl lightly and it fired up. Thought I was done but then it started to puff black smoke. If I close the fuel it does that until it smooths out but just a second before it stops. I pulled the bowl assembly off and attached to a hanging fuel tank. It does not overflow. Stops with fuel at about level with float pin. This carb has an o-ring on the nozzle and and in front of the main jet. I'm wondering if either could create a flooding situation no matter if fuel in bowl is not excessive. I have all the replacement bowl parts except the bowl and main jet.

[KE4AVB]

Tecumseh Married Series 7 carburetor.

Yes either o-ring can over rich conditions just like the main jet[s] o-ring[s] does on the Nikki carburetors. Also note the main jet appears to be plastic so it may causing problems too but if ran fine before putting away I would try the o-rings first.

[38racing]

just started taking apart. No spring on the nozzle. I think I felt the spring on the main jet. I'll know if I ever find it. As I went to pull with hook something missed the container and fell to floor. I glimpsed some pink (jet). All that was left in carb was the jet oring. Going to be searching the floor for awhile tonight. Too humid in the garage right now.

[38racing]

Doesn't look like I'm going to find the dropped jet. My aftermarket market supplier has several of the bowl kit but when I look up jet for the carbs they fit nothing matches my number. Funny though that I have jets that I believe are from one of two carbs feeding the 22 hp vtwin and another from maybe single carb on a 13 hp. One is purple and one is black. On both a .90 mm pin enters but the 1.00 pin does not. Probably will try one of them for now with new orings and needle/ seat.

[38racing]

I decided to order a replacement carb but meanwhile I put the carb back together with one of the jets I had, new orings and new inlet seat. So it started and ran ok (no black puffing) so I try a test cut. About 10 minutes and I sense some poor performance. Reached a point where engine stopped. Could get it restarted but need to choke to keep running. I tested for spark and it stays until the end. Changed plug anyway because it had a ngk from same pack of 4 that 1 failed on the zt50. Although backfire solenoid had tested good and still clicked I considered a bad contact to it and so replaced with a bolt. No change. Done working on it for tonight. Although I added fresh gas to what was in the tank I'm now thinking original gas is bad. Will drain completely tomorrow.

[38racing]

I guess it wasn't the fuel quality. It's just not pulling it through. Starts on choke and then just stops. Will stay running as long as I spray carb cleaner in it. Thinking maybe something in the body is blocked so it's in the USC now. Funny thing on finding correct jet. The man. number on the carb is 5292. I can't find it in the list. The ov490ea calls for carb 640330 for the sample of 8 or more spec numbers. It's listed in man. list 5274. Since the list shows the same carb number with multiple man. numbers I guess 640330 could well be 5292. for interest I looked up the other carbs that the ebay seller says are replaced by the one he claims replaces 640330, they being 640072,640159 and 640034. looking up the jet on these three says 640040 yet jet for 640330 is 632788. Quite likely another ebay seller misinformation.
and an additional tidbit. My cdn parts place still has a where used for part. My jet 632788 is used on 4 carbs and each is listed with mfg number. My 640330 shows as 5274. So I entered 5274 mfg as a modle search and it showed my carb. I then tried 5292 mfg and it finds nothing. So there's no record of a 5292 in the system yet that's clearly stamped on my carb.

[38racing]

New carb arrived today but I'm going to try old once more. In reviewing it i had a thought. Nozzle is held up by spring but there is tension from o ring. Possibly I pushed it down too far and spring isn't overcoming oring tension and oring or spring is blocking fuel coming through jet. I'm going to install so nozzle upper flange hits the cover/gasket

[bgsengine]

New carb arrived today but I'm going to try old once more. In reviewing it i had a thought. Nozzle is held up by spring but there is tension from o ring. Possibly I pushed it down too far and spring isn't overcoming oring tension and oring or spring is blocking fuel coming through jet. I'm going to install so nozzle upper flange hits the cover/gasket

Yes, correctly installed the nozzle will be spring loaded tension against the gasket surface (it wants to push gasket away from bowl) if not, then spring isn't right or nozzle is stuck or nozzle too short. O-ring on bottom of nozzle (side that goes against spring) should be a snug fit down the tube but not so tight that it holds spring compressed.. if it seems loose, might have wear in the bowl that requires a bowl kit.

[38racing]

I fibbed. I said that I put new seat in. Technically no. I thought one of the bowls from working on the vtwin had a new seat and never got used so I popped it and used it. Today after putting my nice usc'd body and bowl kit back together it started and was running fine until again it just stopped. So I pop off the bowl and it basically empty with float down but when I open shutoff (bypassed pump for testing) it doesn't fill. Jiggle it and it then fills. In case debris I remove float attached to high test tank. Came out like a fountain. Reinstalled and next test it still stopped with empty bowl. Now I did replace needle and seat with new from package and ensured seat was bottomed. Now it runs great again. Maybe the original problem was just the needle seat. First with not enough fuel and then wirh too much. Should learn not to try short cuts.

[KE4AVB]

Short cuts usually get me in trouble so I learn to avoid them. In this case it sounds like you had a rare tough problem to find but yes checking for fuel on dying engine is one step we all should check for as float valves do stick that why many have clips on them or the float. Can't always be bench test for either as sometime it takes the engine vibration to cause them to hang.

I admit I have very experience on the Vector carburetors as Tecumseh engines here are rare to come in the shop. I do have a couple customers now that have v-twins and they don't have problems with the engines except one time where the twin carb setup choke wasn't fully closing one side. Easily fixed.

The best advice I can give here is not get stuck on one thing and keep an open mind set to other possibilities. And here I do listen to my customers, fellow techs, people that only had similar problems, even people with no knowledge of repairs can suggest something that can be the source of problem. It like the recent Hustler that was throwing and breaking belts. I tried everything I thought of but the cause was staring me right in the face. Once my UPS driver sub mention that he had one that the hydro fan was the cause I checked and sure enough it was the problem. I even had a customer years ago when I was working on a desktop calculator out of curiosity what a component was. She unknowingly pointed to the cause of the problem and I had been over looking it for 30 minutes. It was a little embarrassing but I learn from that experience to have an open mind and to listen to others.

There will always be something I must learn a new way getting a repair done too. Like the removal a 6204 bearing outer race that was split half off and no easy way of getting a hold on it to pull it. I ended up destroy a few chisel tips but found a grind that worked on separating it. Now that problem is getting the bottom plate to seal. According to vendor I was supposed just use the paper gasket but was leaking after I added the gear oil on the bench. Broke it down again cleaned, spray RTV surface prep and applied RTV. Going to bench test again today since 24 hrs is up. Here's to hoping that this seals it. I did notice a white sealant on the mating surfaces when I initially cleaned them on it must had been a problem at the factory.