20 hp Briggs

FredFuentesJuly 11, 2014

I just finished mowing our back yard[ appox. 1/3 of an acre. After a cooling off time, Tried to start and park in our shed. It would not hit a lick. This mower is 12 years old with no former issues. I next drained the fuel, changed the plugs and fuel feed line. The eng. continued to flood on start attempts. Changed the needle valve, inspected the seat. The float is plastic with no fuel inside. My owner manual shows a picture showing how to adj. the carb. It also shows the fuel pump[ with thee screws] mine has four screws. It also has a non adj. idle mix. jet, mine just has a hole. I checked with our local mower shop and they advised me to plug it, I did no help. Now after checking the needle valve again, it started up but before reaching on speed the remote throttle control linkage moved to full throw???? What controls the remote linkage ? The rigging seems to meet the specs. in the picture. I spent 50 years fixing air plane engs. but this has me baffled.

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tomplum

Well, the linkage is controlled by the governor. It sounds like that you are working on an opposed twin from your carburetor notes. Some 4 screw models have a removable fixed jet and some just have the well, but nothing else. Is the engine still flooding? I assume that the proper needle valve /kit has been installed or was there a question in that regards? Seats are available as well if needed. Model and type should you need more info. Part numbers that you have installed could be helpful too. And be sure that if fuel had entered the sump to change the oil also.

    Bookmark   July 11, 2014 at 9:25PM
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FredFuentes

Thanks for you input. The engine is a Briggs& Stratton Mod. 461707 installed on a Garden Way with 46" blades. Carb. p/n 692815. The needle valve I installed was p/n 808798. The local mower shop says on this model the seat does not require changing. Yes it foods every time. The only other thing which may have an input, was after I mowed, I used the mower to blow away leaves to the back fence. The leaves were blowing everywhere. When I checked the intake filter , it was covered with leaves.Is there something which could be plugged up? What does the governor monitor, crankshaft RPM? Is there some way to check the governor? I also checked the flywheel keyway and the spark plugs for fire.

    Bookmark   July 13, 2014 at 9:39PM
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tomplum

Well, the governor isn't causing your flooding issue. With the price of the complete kits vs the needle that you installed- they should have sold you the whole thing. I assume that you used the gold needle of the two? Seats can wear. Especially if the fuel tank is under the hood, the fuel pump may contribute to the flooding. True a plugged bowl vent can also, seems unlikely. In an odd case, sometimes the needle doesn't hit the center of the seat right away after service. The pump fills the bowl and keeps filling. Sometimes a tap on the front of the carb body as you begin to run it up will let it find its spot. Sometimes we also take for granted that a plastic float will always pivot on the pin. Just be sure it does.

    Bookmark   July 14, 2014 at 1:21AM
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FredFuentes

The needle valve cost $22.00. Received two valves, one long [ which is too long] and one gold short. Where does the bowl vent? I can not get it to run to try the tapping but will try some way to check this info. Thanks, Tom. I will again check with our local shop about the seat.

    Bookmark   July 14, 2014 at 9:33PM
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FredFuentes

The needle valve cost $22.00. Received two valves, one long [ which is too long] and one gold short. Where does the bowl vent? I can not get it to run to try the tapping but will try some way to check this info. Thanks, Tom. I will again check with our local shop about the seat.

    Bookmark   July 14, 2014 at 9:34PM
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walt2002

$22 for a float needle? Good gosh, they saw you coming. Try running it without the air filter, a plugged air cleaner will certainly cause flooding but not gas running out of it.

I would install a gas line shut off valve and use it when not running IF the gas tank is higher than the carb.

Walt Conner

    Bookmark   July 15, 2014 at 1:01PM
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tomplum

The reality is that the little float valve pack is that much and the whole kit complete w/ pump is another $10-15. Why they choose to package these two needles together makes no sense. I think the long needle is fits Vanguard engines. You will detect the bowl vent as you clean the passages in the body and top.

    Bookmark   July 16, 2014 at 12:01AM
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FredFuentes

I don't work on this every day, but I decided to check the compression, using the thumb method.The two cyl. seems equal. I noticed the liquid in the intake manifold. It was a little brown and smelled like fuel. I checked the oil dip stick, and again it smell like fuel???

    Bookmark   July 17, 2014 at 9:40PM
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FredFuentes

Does anyone know how the remote throttle control works? Our local mower show does not know. I tried to find out with posts on the internet , but could not find anything. I called Briggs, no one there knew either. I will try a post on their site.

    Bookmark   July 24, 2014 at 10:20PM
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tomplum

Could you clarify your throttle question? Your throttle cable essentially gives the governor an operating range to do the best it can with. IE when you have it wide open, the governor does its part to keep the engine speed consistently close to the max set RPMs. A small governor gear is driven inside the engine which has a little weight set which is in contact with the internal governor arm which through its linkage manipulates the throttle shaft on the carb. Fuel in the oil is not good. In these engines, a trace of unspent fuel in the intake manifold is not abnormal.

    Bookmark   July 24, 2014 at 10:52PM
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FredFuentes

Thanks, Tom. The oil in fuel was from a new fuel feed line I installed, it's o'k now. After checking the needle valve and float, sopping up the residual fuel in chamber. The engine started, but before coming on line,the remote throttle control linkage shiffed to max throw, the engine flooded and shut down. If I disconnect the remote linkage will the engine overspeed?

    Bookmark   July 25, 2014 at 10:34AM
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tomplum

Yes, it will overspeed. Are you saying that you were getting fuel into the oil via the hose that comes out of the bottom of the fuel pump? You could try to manipulate the linkage manually to get a different result- but I have to wonder if the pump is loading fuel into the engine.

    Bookmark   July 25, 2014 at 12:37PM
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FredFuentes

The oil I thought was getting into the fuel was from a new fuel feed line I installed. It discolored the fuel and I thought it was oil, but turned out not be. As to the remote linkage, it moves too fast. As the engine is accelerating, the remote link moves to max throw and the engine floods out and dies before the engine is on speed. I thought of the fuel pump, maybe it has a check valve which restricts the fuel flow.How can I check the fuel pump???

    Bookmark   July 26, 2014 at 12:47AM
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tomplum

It is possible to disassemble the pump and see damage, but really a new pump kit should be installed if it comes apart anyways. Pull it apart 1 layer at a time and document it so it has hopes of being reassembled correctly. You still have a problem with that carb flooding- and it could be a fuel pump issue or? You may want to buy the complete carb kit this time for the little in price difference. I quit ordering the needles and pump kits separately. I still order the body gaskets on their own though. Or a new carb at low low since I know ya price of something like 220$ if I recall!

    Bookmark   July 26, 2014 at 12:52PM
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FredFuentes

Thanks, Tom. I think I have found my problem. After our last exchange, I pulled the fuel pump [ four screw holer] and visually checked the parts. The pump has two chambers and two valves. The bottom chamber has the fuel feed line and a valve. I held the two pump parts together and blew in to the fuel feel line, almost no resistence????. Next after your input I will, pull the upper section of the carb. sop out thr fuel and try to blow air into the fuel feed line to the float chamber of the carb. If the air goes thru, I think the pump is at fault.

    Bookmark   July 27, 2014 at 10:30PM
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FredFuentes

Tom, a follow up of my last. I took off the top deck of the carb. Reinstalled the fuel pump, hooked up a flex tube and attached to the fuel inlet. I blew air and the air went thru the pump to the float valve chamber with very little resistance??? The fuel pump has an upper and lower chamber with each having a vlave. What is the purpose of the valves? I then filled the float chamber with fuel and attached the flex line again and blew into the tube. No leakage. I think my problem is the pump. In my many years wih airplanes, we had schmatics and multi engine aircraft, which we could always check the next engine.

    Bookmark   July 29, 2014 at 10:08PM
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bill_kapaun

The valves are simply check valves.
One allows fuel from the tank to flow to the carb, but not back to the tank.
The 2nd one allows fuel to flow to the carb, but not back to the pump.

    Bookmark   July 29, 2014 at 11:00PM
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FredFuentes

Thanks, Bill, I would think those valves work that way, but both of them failing at the same time, does not compute. I bought a complete carb. ovhl kit today, but the parts for those valves was no there. I will take it back tomorrow.

    Bookmark   July 30, 2014 at 10:49PM
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