Masport 430 mower engine pulsing

Roy Cagle

• 1545 Answers
• Posted on Sep 05, 2010

SOURCE: Bolens MTD push mower with B&S 4.5HP

This is probably not a blown gasket issue. A bad head gasket can allow oil to enter the cylinder head/combustion chamber if it's not sealing off the valve area. A simple suggestion is to check on the engine opposite the carb side for the oil/crankcase breather. It will have 2 screws holding it onto the block. It has a type of filter media in it that traps excessive oil and oil vapors from the engine. It is also connected by a tube to the air filter housing. When you tipped, you probably put too much oil in the breather and it was inducted over to the air filter/carb intake side.
Clean or replace the breather after checking it and also make sure you haven't overfilled the Briggs with oil and only use SAE 30 in the engine. Muti-viscosity isn't recommended in summer unless you run synthetic, then it is OK.
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SOURCE: four stoke mower. Mower starts and runs ok but

Your ignition coil is failing when it gets hot.make sure the cooling fins on the flywheel are not plugged up.you will probably have to replace the coil.

SOURCE: i've been trying to start

I had the same problem. It turned out to be a blocked carby and the way to fix is as follows;
- remove air filter
- start mower (assuming it now starts)
- place open hand over carby hole and then remove. The force of the spinning blades will **** through the blockage.

You may need to prime it first.

Hope that helps.

Kelly

• 3740 Answers
• Posted on May 22, 2011

SOURCE: The Briggs and Stratton engine on my lawn mower

Hi and welcome to FixYa, I am Kelly.

There is a brake on the flywheel with a kill switch on the flywheel brake mount (behind the flywheel) on the back of the engine. Usually you can correct this by readjusting the user safety handle / bar cable at the back of the engine on the side of the flywheel brake bracket. 1/4" head screw to lift of the plastic cover most of the time and then loosen the cable clamp / mount .. pull the cable a bit furter away from the original position re-tighten clamp and squeeze the user safety hande to make sure the kill switch is no longer activated when the user safety bar is against the mower handle.

Since you did not include an engine model number I can not discuss specifics on you engine. I can do so with your engine model number.
GENERICALLY speaking
If that does not correct the problem... if your engine has a LOW oil level sensor make sure the engine OIL is fully serviced. If the oil is fully serviced and you still have the problem on sensor models... disconnect ONE wire from the low oil level sensor and re-test spark. If disconnecting the low oil level sensor wire corrects the no spark issue.. remove the sensor and clean through the 2 holes in the barrell of the sensor with carb cleaner... several times to flush it.

On engines that do NOT have a low oil level sensor you have to inspect the black wire coming from under the flywheel for any signs of melting or chaffing. Usually you can repair any noted wire damage with electrical tape. Note fuel eventually eats the adhesive off of the electrical tape. I use electrical tape and a mini zip / cable tie over the tape so it does not migrate or come off.

Thanks for choosing FixYa,
Kelly

Curtis Sewell

• 7482 Answers
• Posted on Jun 19, 2011

SOURCE: Briggs and Statton Sprint Lawnmower engine 3 years

Hi
Sounds like you have dirt/debris in your carburetor jets,fuel passages or a diaphgram that is becoming non-flexible.
Be sure to check your fuel tank for water and dirt/debris, if there is water/debris then you need to clean your tank.
Also check you fuel line condition after a while they will degrade and need replacment.
Make sure you are getting spark at the spark plug, to do this:
Check/Clean/Replace your fuel filter if you have one.
When you remove your fuel lines from the carburetor be sure to make a drawing to how the lines are connected to the carburetor.
Also make sure you are using fresh fuel...and oil mix if your using a two cycle mower or weedeater with the oil to the right mixture and not too much oil as it can cause hard starting.
If the mower/weedeater is over a couple of years old, then I recommend that you buy and install a new carburetor repair kit,because the diaphragm will get hard and that will cause it to be hard to crank.
Sounds like you will need to clean the carburetor or replace your carburetor internal rubber parts like the diaphgram and O rings.
I recommend that you use a laquer thinner type cleaner to clean and dissolve the laquer build-up in the float and needle jet passages.
Be sure to remove all plastic and rubber parts before using the laquer thinner because it can dissolve the plastic parts and render them unuseable.
Be sure to use compressed air to blow out all the fuel and air passages.
Be careful when blowing out the passages, because there are sometimes small rubber type seats in the bottom of some of the passages.
Sometimes you can get by with priming the carburetor or using starting fluid and letting it run a few times like that and it will flush the gunk out of the jets,but most of the time you will need to rebuild the carburetor.
Keep in mind that the float (if you have one) for the carburetor must be level when you go to reassemble the carburetor or follow the instructions you get with the carburetor kit.
When you clean your carburetor and remove the jet screws, you will first need to lightly seat the jet screws.
But before you lightly seat the jet screws count the number of turns it takes to seat the jet screws from their original position.
Be sure to mark the turns down on a piece of paper.
That way when you put the jets back in, you know to lightly seat them first and then turn them back out to their orginal position before you started.
Once you have your carburetor rebuilt that should solve your problem.
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