Briggs & Stratton Hard to Start

WranglerX · Jan 19, 2020

Have JD L120 mower with 20hp Briggs Intek "V" twin and its miserable to try and start....

Did internet search and solution seems to be adjusting valves to .004 for intake and .006 for exhaust.... According to some "compression release" mumbo jumbo with cam...

Well that is not solution. valves are at tight .004 & .006, some people suggest a .003 and .005 but .003 & .005 feeler gauge shows them almost loose... So I believe I'm in the ballpark...

Have gone over engine and its getting fuel, no intake or exhaust leaks, choke seems to work and solenoid on float bowl seems to work....

Runs great, once started....

Any suggestions appreciated...

Dale

RandyT · Jan 19, 2020

Make sure the choke is closing all the way. Just take a few thousands from complete close to make hard starts. Happens a lot with the single throttle/choke control systems. Cable slides in the clamp or gets some wear/slack in the cable and then choke doesn't close properly.

Fuddy1952 · Jan 19, 2020

Can you start it easier with starting fluid? Of course air filter off, no choke (open).
New spark plugs? Check spark intensity?
Is it cranking over fast? Of course plugs out it will crank faster...but does it have a good intense spark?

Maxify55 · Jan 19, 2020

You didn't mention that you'd moved the motor to TDC on either cylinder for the test.
It's critical that you do it for the gap set

WranglerX · Jan 19, 2020

Maxify55 said:
You didn't mention that you'd moved the motor to TDC on either cylinder for the test.
It's critical that you do it for the gap set

YEs I followed procedure .. Actually procedure say to go to TDC and with SP out put a dowel in spark plug hole and go past TDC till dowel moves in about 1/4 inch...

Good spark, not new plugs but they are burning clean (light tan/brown) and are gapped properly.......

And yes starting fluid (actuall carb cleaner- less volatile than ether) helps...

Dale

Travelover · Jan 19, 2020

Have you taken a compression test? To run, you need adequate compression, fresh fuel and a properly timed spark. The problem is always one of those three, though it is often not obvious which is the problem.

bindian · Jan 20, 2020

Rebuild the carb after giving it a soak in an ultrasonic cleaner. You might have blockage around the idle jet.
hugs, Brandi

Richard001 · Jan 20, 2020

DL Meisen said:
YEs I followed procedure .. Actually procedure say to go to TDC and with SP out put a dowel in spark plug hole and go past TDC till dowel moves in about 1/4 inch...

Good spark, not new plugs but they are burning clean (light tan/brown) and are gapped properly.......

And yes starting fluid (actuall carb cleaner- less volatile than ether) helps...

Dale

Does the engine crank well with the starter? As others have implied, if the valves are not set correctly, the compression release will not function properly thus not allowing the engine to crank at a speed needed to start.

WranglerX · Jan 20, 2020

Battery and starter are good, cranks good.... Valves are set buy the book.... Actual starts easy when hot...

Issue with starting is when it has set for a week or two without being run ... Probably should have mentioned this in first post...... Much like carb bowl is dry and won't fill.... Suspect fuel pump, but then once it runs a bit it starts easy...

Dale

Richard001 · Jan 20, 2020

DL,
If you don't have the service manual for your engine, go here:
https://www.mytractorforum.com/threads/briggs-statton-repair-manuals.242387/

As someone else said, make sure your choke is working properly.

This engine useis a pulse pump. Could be that it is not working correctly. Check the pulse line.

From the manual:
FUEL PUMP
The fuel pump, mounted on the No. 1 cylinder shield,
allows remote fuel tank installations. The fuel pump will
prime at 12” (30.5 cm) maximum lift. Fuel pump pressure is
1.5 psi (0.1 Bar ). The pump is operated by pulsating
crankcase vacuum from the engine. The vacuum pulse line
is installed on the No. 1 cylinder valve cover, Fig. 33.
Note: Fuel pump is available as an assembly only.
Replace fuel lines and vacuum pulse line if stiff and brittle.
Note: An air leak at the fuel pump pulse line hose
connections will result in improper fuel flow.

Richard