briggs 5hp i/c nonstart

dieselade · Mar 1, 2015

ok, it will start. after 20 pulls with ether at pull #16. then runs good.

or, remover air cleaner, put hand over carb and pull rope will start on 4th pull. then run good.

or, take plug out and put shot of gas and will start.

new diaphrm pump thing.

pulse jet with the diaphram pump on side of carb.

why does it start good when i cover carb with my hand. its like it cant get enough suction to pull fuel up from tank.

El Toro · Mar 1, 2015

When you cover the throat with your hand it creates more vacuum. Check for a leak on the intake manifold. That's how we checked cars and trucks with a mechanical fuel pump for a defective pump. Check your compression too. Hal

dieselade · Mar 1, 2015

ok, eltoro, thanks for the quick response. there has to be good compression or it would not run great when started. this is on a wood splitter and it has extremely good power.
I will be checking the gasket between carb and fuel tank when weather warms up a little more.
there is a hole in the butterfly. I know most of them do, but wonder if it is too big. just a little smaller than a pencil. I would like to temporally close that small hole but don't know what with. cant get a nut and bolt in there.

T.R.K. · Mar 1, 2015

I assume its the L-head 5 hp with the fuel tank mounted under the carburetor.

While you have it apart, put a little fuel in the cup that feeds the short pickup and see if it runs back in the tank. There may be a pinhole that cup.

That engine has to fill that cup before it can provide sufficient fuel to the engine. the diaphragm pump does this. I have seen the cover plate warped enough it does not seal that diaphragm properly.

I have also seen 2 engines where the main pickup swelled to the point it was restricting the entry of fuel by being jammed against the bottom of the tank.

It should be firing immediately on either. You probably have a valve or ring problem and the compression is lower than normal. Carburetor cleaner is much more friendly to these engines than either. Either tends to break rings and cause scuffed cylinders, which lead to ring problems too.

I have also seen pinholes in the long pickup that cause start/run issues.

old · Mar 1, 2015

Very simple when you put your hand over the air intake you are super choking it so it gets almost no air. Good chance you have a vacuum leak or some such type problem and i is not sucking in as much gas as it should when you pulling the rope start but after it is running it then pulls in enough to run due to the higher RPMs

jeffcat · Mar 2, 2015

Wait a minute! How old is this engine??? If it is a Pulsa Jet then there are two things to check. First go by the carb kit. It has the rubber diaphragm with the little hooked wire for the choke. But the big thing is a warped gas tank. Now you can fix it your self. Take a BRAND NEW piece of like 200 grit wet dry paper. Put it on a DEAD FLAT steel table or such, Gently rub the upside down tank back and forth till there is a shinny surface all over that gas sump. Don't need all of it just enough so you will get a positive seal. Follow the directions on preloading the diaphragm and you should have it. Fixed a BUNCH of them years ago. After you fix it they start first pull almost every time,

joe csuti · Mar 2, 2015

When you replaced pump diaphram did you install spring/cup on correct side of diaphram?

Spring is supposed to be installed in cavity of carb body with cup on top against diaphram,both will also install in cavity on pump cover which is the wrong side of diaphram,been there/done it when repairing carb in a hurry.

Other things to check.
1-screen filters on pickup tubes not plugged/restricted due to varnish/dirt.

2-check pickup tubes for hairline cracks/splits.

3-check that tubes are tight in carb body.

4-as has been said check that pump diaphram cover
not warped by putting on a pc of glass & look at from all sides/underside of glass to see if flat,I've also seen covers warp.

Hoenes · Mar 4, 2015

Had a wood chipper with that engine. Turned out to be the main pickup tube clogged up. It looked like a brass plug was screwed into the bottom of it. (Some models bypass that and use a different pickup), just couldn't see the hole though. Fixed it by rodding out with torch tip cleaners.

JT · Mar 5, 2015

I would do a compression check and/or a cylinder leakdown test, that engine has some age on it and by putting either in it, basically like compression in a can, sounds as though you have low compression or maybe valves not seating and cannot create enough vacuum to pull fuel all the way from the bottom of the tank to the cylinder.

briggs 5hp i/c nonstart

dieselade

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El Toro

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dieselade

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T.R.K.

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old

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jeffcat

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joe csuti

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Hoenes

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JT

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