Briggs won't start, I won't give up

bcarwell · Mar 19, 2010

Got a 6.5hp OHV Briggs on a Sears pressure washer about 8 years old. Started about 5 months ago no problem. Won't now.
Gummy old gas (I know, I know...). I (1) drained old gas from tank, got fresh, (2) took off carb, sprayed carb cleaner through every orifice I could find and blew them out with canned compressed air- about 15 minutes worth of clean/spray work, (3) reinstalled carb and still doesn't start. Maybe I missed something ?
Took the plug off and cleaned it, and while at it closed plug port with finger and could feel suction/compression. Tried starter fluid and it would run for a second off the fluid, then stop. Indicated to me no spark problem but a fuel problem. But tested with inline plug tester to be sure and the neon light lit, so I still suspect fuel problem. Took the bowl off and fresh gas is in it, so no fuel line problem.
So... what would YOU do next ? Should I take carb off again, take off gaskets, and this time SOAK it for an hour and blow it with "real" compressed air from my compressor.
Or take up mah jhong, whist or curling ?

Bob

Travelover · Mar 19, 2010

A couple possibilities. Could have a sticking valve and enough compression to feel on your thumb, but not enough to fire on gasoline. Another possibility is that the main jet is still plugged with gunk.

zzvyb6 · Mar 19, 2010

See if it will run for a while when you continously spray small amounts of WD-40 into the carb intake. The extra rpm may suck out the problem jet. Could be a leak in the intake manifold (or a cracked intake pipe). Better to use WD-40 than raw gas dripped into the intake. Is there a fuel pump involved here? Check the diaphragm...

California · Mar 19, 2010

Can modern WD40 be used as starting fluid? I read somewhere they took out the combustible component.

As for that Briggs, when I have had a problem like that it has usually been a stuck float needle.

In my experience that engine will run (not very well) on gas that is a couple of years old so long as it hasn't turned to varnish in the passages.

Treemonkey1000 · Mar 19, 2010

You may want to see if the gasket between the carb and head is leaky. That sure sounds like goobers in the carb still though. Be careful about forcing too much air into the carb. Usually taking them apart and cleaning out the needle valve or diaphragm and flappers fixes most carbs. Does it have one of those pump bulbs to prime the carb? Air leaks in that will not get you enough fuel to run also.

KubotainNH · Mar 19, 2010

I agree with Travelover, it could be a sticky valve, old gas will make them stick but not as much on OHV. Compression tester is the real check but if it sounds like it's running somewhat normal with gas/starter fluid in the intake then sticky valve is doubtful. You can also unscrew the valve cover and watch the end of the valves where they touch the rockers while turning it over. As for pouring gas down the carb, I see no issues with this seeing it's not a 2cycle. The carb dumps raw gas down it constantly, the cylinder gets lubed by the crankcase oil. I would bet the carb is still cruddy, you can have someone clean it in a tank but usually carb spray through every hole you can find will do the job.

Ken · Mar 20, 2010

Is this the engine that has the primer bulb on side supposed to press 5X then start? if so I have seen several that there is a small air leak and gas is not siphened to carb. simular to a choke on older engines.
Sears wants you to exchange the whole carb. At one time they wholesaled these mowers and pressure sprayers to lot sales for truck load dealers 1 day sales then travel to next town.
I bought 2 lawn mowers and 2 pressure sprayers of this type low price for a reason.
ended up giving away buying another brand that is still running.
ken

paccorti · Mar 20, 2010

I'm very suspicious of a fuel delivery issue. Carbs are tricky and there can be a lot of passages to clean. Are you sure you got them all? I'm more familiar with motorcycle carbs but there has got to be a jet sitting in the fuel bowl (this is the main jet). Did you clean that one? The main jet is brass looking (usually) and has holes on the top and bottom. Remove this jet from the carb body and clean it individually. See if you can look through the passages of the jet. Since this jet sits in the stale fuel it is usually the first to gum up.

My wife has a moped and the main jet (in the fuel bowl) constantly clogs. If it is clogged it flat out will not start no matter how hard you try.

When you clean the carb (and jet) be sure to use those little red tubes to direct the cleaner into the passages - just be careful it doesn't shoot back into your face (I've had it happen).

Peter

RandyT · Mar 20, 2010

the bowl nut is the main jet and is probably still plugged. a small diameter wire or a torch tip cleaner should clean it out then spras carb cleaner through the hole and it should stasrt then.

bcarwell · Mar 20, 2010

Thanks to everyone for the help. Answers to questions: no, no fuel pump, its gravity feed. And no, there is no prime bulb to push, so no source of air leak there.

Consensus sees to be that I must have missed a port I didn't clean, maybe the float needle, main jet, or somewhere else. So I'm gonna take off the carb, soak it in carb cleaner (after removing the gaskets of course), and shoot it harder with <real> compressed air, tighten the bolts a little tighter in case there was air leaks,and try again. Carb rebuild kit is only $15 so if this next attempt fails, I may try that. Remember though it <ran> about 4 months ago last time I tried it so there's soap in my hole err hope in my soul.

Will keep runnin' this play til I get it right... Then its on to replacing a transaxle on my cheapo Murray riding mower...

Thanks again all,

Bob