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Discussion Starter · #1 · (Edited)
I have a 16 horse Briggs powered pressure washer that I can't get going. It all started when I tore the carb down to clean it out. It sat for a while and the carb was gummed up. I had it running again after a good scrubbing and used it to pressure wash the side of my house. Soon after that the float started to leak fuel that found its way into the motors lower end.

I purchased a carb rebuild kit because I knoticed the neddle valve had a rubber tip on it that looked to be worn down. I recieved the new one today and installed it. I ran the machine for a while and pressure washed a side walk. I shut it down long enough to add more fuel and it would not start after that. I pulled the air cleaner and could see small stream of fuel trickling in the intake.

I don't have a clue why the float is still leaking fuel. The seat where the needle sits looks to be ok. I suppose it could be uneven or have deposits on it not visible to the naked eye. I also suspect the float could be out of adjustment and might not be raising high enough. I did not do anything to the float to cause it to be out of whack. But you never know what may have happened to it.

I am at a loss with this one. This is what the carb looks like in diagram form below.

Thanks in advance for any help on this one.:thanku:

http://www.partstree.com/parts/?lc=briggs_and_stratton&mn=303442-0357-01&dn=96910006
 

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I had a number of those engines with that carburetor- it was about the only trouble spot on the whole engine. Not too much trouble with flooding, but was constantly cleaning the idle jets. Another thing to keep in mind with that setup is the carb could become heat-soaked on shutdown, leading to some flooding- that could be happening to you. You might want to get into the habit of shutting the fuel off just prior to shutting the engine off. It's a good habit to get into with any gravity fuel system.
 

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The seat might be loose, or have a rough spot. The float could be sticking, perhaps hitting the side of the bowl. Have you tried gently tapping on the bowl?
 

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"You might want to get into the habit of shutting the fuel off just prior to shutting the engine off. It's a good habit to get into with any gravity fuel system. "

Agree but would add that it is a good idea on any system where the gas tank outlet is higher than the carb inlet. Gas will siphon thru fuel pump equipped systems.

Walt Conner
 

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Discussion Starter · #5 ·
I had a number of those engines with that carburetor- it was about the only trouble spot on the whole engine. Not too much trouble with flooding, but was constantly cleaning the idle jets. Another thing to keep in mind with that setup is the carb could become heat-soaked on shutdown, leading to some flooding- that could be happening to you. You might want to get into the habit of shutting the fuel off just prior to shutting the engine off. It's a good habit to get into with any gravity fuel system.
That is the only way I can get it to start is by shutting the gas to off. This engine has been rock solid reliable for over 15 years. I don't think we ever had to shut the gas off on it ever.
 

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Discussion Starter · #6 ·
The seat might be loose, or have a rough spot. The float could be sticking, perhaps hitting the side of the bowl. Have you tried gently tapping on the bowl?
The needle valve seats right onto the casting on this set up. It does not have any type of seat that can come loose that I can see. My next step will be to tear it back down and examine everything very closely. This all started to occur after I tore it down for the first time to de-gum the bowl.
 

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Doesn't look like much volume in the float pontoons for generating force to seal the needle & seat, even with minimal (gravity feed) fuel pressure. Check EVERYTHING closely: seated float level, direction of the 'U' shaped float pin's installation, even the baffle which shields the heat from the exhaust from the carb. A member here had a twin with a fuel boiling problem which was traced to exhaust leaking between the head pipes & muffler. Another had fuel control issues 'til he noticed a newer model of his mower had an improved heat baffle; he bought the newer version & solved his problem. The ethanol blended fuel is proving more problem prone than the 'straight gas' of old. Lower boiling points, quicker breakdown, & harder to remove varnish & deposits are just some of the problems. We don't store gas longer than a month anymore, it goes into a car or truck with computer mixture control for relatively quick consumption. I won't put bargain off-brand fuel in our equipment either. I can tell from the proximity of the heads on my ol' shovelhead to a sensitive part of my anatomy that the bargain brands are causing higher head temps! Oh, another thought, see if there has been a helper spring added by the carb manufacturer to help the needle seal to the seat better.
 

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Discussion Starter · #8 ·
Doesn't look like much volume in the float pontoons for generating force to seal the needle & seat, even with minimal (gravity feed) fuel pressure. Check EVERYTHING closely: seated float level, direction of the 'U' shaped float pin's installation, even the baffle which shields the heat from the exhaust from the carb. A member here had a twin with a fuel boiling problem which was traced to exhaust leaking between the head pipes & muffler. Another had fuel control issues 'til he noticed a newer model of his mower had an improved heat baffle; he bought the newer version & solved his problem. The ethanol blended fuel is proving more problem prone than the 'straight gas' of old. Lower boiling points, quicker breakdown, & harder to remove varnish & deposits are just some of the problems. We don't store gas longer than a month anymore, it goes into a car or truck with computer mixture control for relatively quick consumption. I won't put bargain off-brand fuel in our equipment either. I can tell from the proximity of the heads on my ol' shovelhead to a sensitive part of my anatomy that the bargain brands are causing higher head temps! Oh, another thought, see if there has been a helper spring added by the carb manufacturer to help the needle seal to the seat better.
I was wondering about the U shaped pin myself. I will compare that to the diagrams.

How does one determine seated float level?

This thing was heat soaked. I should have let it cool off some before adding fuel. The new fuel blends make sense. Heat was never an issue in the past. But like you said, fuel is different now a day.

Thanks for the tips. I will be tinkering with this tomorrow. :thanku:
 

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Discussion Starter · #9 ·
In diagram box 91, there is a 45 degree port sticking out of the carb very near the choke assembly. When I tore the carb down the first time, I knoticed this port was open and very dirty. I cleaned it up and installed a cap onto it. I have no idea what went on this port and why it was open. The port can be viewed in the diagram box 91 below.

Thanks for any help.

http://www.partstree.com/parts/?lc=briggs_and_stratton&mn=303442-0357-01&dn=96910006
 

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I couldn't open the diagram, but:
If that is the bowl vent, it needs to be open to atmosphere. My friend had a Jaguar that someone had pinched the bowl vent shut, and it continuously flooded because the fuel level did not rise in the bowl, since there was no way for the air to get out, and the fuel was forced up the main jet. Because the bowl never filled, the float never floated. It's hard to describe, but the fuel came into the bowl, but went right up the jet since the air couldn't get out of the bowl.
Try removing the cap you put on, and see what happens.
 

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Discussion Starter · #12 ·
Sure the float has no pinholes in it,allowing gas to fill it up and sink it eventually?...
The pinholes are in my brain!

I got it running great today. Stupid me capped the vent hole for the float. I pulled it off and started it up. It starts right up with one or two pulls like it use to do hot or cold.

I never knew floats used a vent setup like this. What keeps dirt matter from entering the vent and winding up in the carb?
 

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Discussion Starter · #13 ·
I couldn't open the diagram, but:
If that is the bowl vent, it needs to be open to atmosphere. My friend had a Jaguar that someone had pinched the bowl vent shut, and it continuously flooded because the fuel level did not rise in the bowl, since there was no way for the air to get out, and the fuel was forced up the main jet. Because the bowl never filled, the float never floated. It's hard to describe, but the fuel came into the bowl, but went right up the jet since the air couldn't get out of the bowl.
Try removing the cap you put on, and see what happens.
That was the solution. Took the cap back off and she runs great.

Thanks everyone for the input. :thanku:
 

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Glad to help.
Sad end to the Jag story - he delayed fixing it, and still drove the car - a '66 XKE convertible (back in the 70's) in fine shape. Since it had 3 carbs, it still ran halfway decently, so he kept driving it to work and planned to fix it next weekend. He never got the chance - the car caught fire at a stoplight, and the entire fiberglass front end burned up, and the windshield cracked, etc, so the car was considered a total loss. To make it worse, he had just rebuilt the engine. Who pinched the breather line? He did it himself, by accident. He did manage to save all his cassette tapes from the fire, though...
 

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What keeps dirt matter from entering the vent and winding up in the carb?
Nothing. There is no real air flow once the bowl is filled. As you now know, the bowl needs to be exposed to atmospheric pressure. You could attach a short length of hose to the fitting, and let it hang down. Maybe even put a loose ball of cotton or steel wool in the very end if you are really concerned. You have used it for years with nothing on it, so just putting the hose on would be an improvement.
 

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The seated float level is measured by inverting the upper casting with all the float/needle hardware in place. The applications which I am familiar with have the float's straight surface parallel to the the casting to 1/16" higher at the toe end of the float. I'll haveto +1 with Fcubman on the open port being a bowl vent. These were directed into the breather end of the carburetor throat in bygone days, but this may well be another accomadation to the EPA Nazis. There was an earlier posting regarding this situation, the expert reply to that one was that "the vent should be connected to the fuel tank vent line." Should your application NOT have a tank vent with an accessible hose, you might want to run a hose from the carburetor vent & route it above the engine, loop it over & back down a short distance, & attach an appropriate sized fuel filter to it & secure it safely out of harm's way with a cable tie. I totally agree that blocking the bowl vent will upset the mixture; even more so on CV carburetors, like the SUs that Jags ran.
Sorry for stepping on your post Fcubman, but I type SO SLOW! :sorry1:
 

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Discussion Starter · #17 ·
The seated float level is measured by inverting the upper casting with all the float/needle hardware in place. The applications which I am familiar with have the float's straight surface parallel to the the casting to 1/16" higher at the toe end of the float. I'll haveto +1 with Fcubman on the open port being a bowl vent. These were directed into the breather end of the carburetor throat in bygone days, but this may well be another accomadation to the EPA Nazis. There was an earlier posting regarding this situation, the expert reply to that one was that "the vent should be connected to the fuel tank vent line." Should your application NOT have a tank vent with an accessible hose, you might want to run a hose from the carburetor vent & route it above the engine, loop it over & back down a short distance, & attach an appropriate sized fuel filter to it & secure it safely out of harm's way with a cable tie. I totally agree that blocking the bowl vent will upset the mixture; even more so on CV carburetors, like the SUs that Jags ran.
Sorry for stepping on your post Fcubman, but I type SO SLOW! :sorry1:
Once running, It ran fine at anything over idle with the vent plugged. It would start to idle rough and puff black smoke after idling for about 20 seconds. It makes perfect sense to me now.

We use to run this power washer in a dirty environment and that is why the vent was so dirty and grimmy. It looked like an open vacuum line to me. I grabbed a vacuum cap and plugged it up. That was when the problems began. I forgot about the cap and assumed the neddle valve was bad. lesson learned.

Thanks again.
 

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Sorry for stepping on your post Fcubman, but I type SO SLOW! :sorry1:
No problem, we're all on the same side!

I think it ran okay above idle because the main jet limited the gas flow, but at idle, there was too much gas being forced up the main jet, so it ran rich.

I'm glad I could help, saleen49.
 
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