Briggs & Stratton 6.75 Quantum engine on Craftsman power washer won't start

DTWinters said:

This may be a stretch but I'm hoping someone can offer some advice.

Last summer, my 17 year old son used my roughly 8 year old Model No. 580.752050 Craftsman power washer for several jobs as he went about making money. I regularly asked him to stay on top of the oil situation. I know he didn't do a great job because one time when I checked the oil was a goopy grey mess. I learned online that throwing some diesel in with the goopy oil can loosen it up and I was able to clean it out and get new oil in there. At that point I didn't look further for how the oil got that bad. I figured it was simple misuse over a long period of time.

A buddy used the power washer this year as he cleaned up his house to sell. Upon return, I noticed that oil was leaking all over the place, so I went about troubleshooting the problem.

I pulled it apart looking for the source of the oil leak which was presenting all over the place and resulting in oil dripping down off the engine onto the power washer frame and onto the ground. I replaced the head gasket and that didn't help enough. I would start up the engine but it would still leak. I realized it might be the shaft seals but had a gasket replacement kit and decided to replace the remaining gaskets first and go from there.

I also pulled the pump assembly off the bottom looking for leaks and then put it back together.

The power washer started right up but I wasn't getting any pressure beyond what came through the garden hose. I later diagnosed that I missed that the key fell off the crankshaft and without it the crankshaft spun but didn't drive the water pump assembly. Suffice it to say that there was some metal paste where the metal shaft rubbed again the slotted metal receiver.

When I put the key back in place, the engine started up, water pressure built up for maybe 5 seconds and then the entire engine died and wouldn't restart.

I figured that with the carb taken off (and the gas tank) to replace gaskets, I must have dislodged some crud and gummed up the jets and the engine was fuel starved. It turned out the float bowl was full of sediment and half the float bowl gasket cracked and fell apart. And the float was heavily varnished.

So, I bought a new carb and replaced it this morning. I got everything together, crossed my fingers, and pulled. And pulled. And pulled some more.

The engine wouldn't start even as it felt like it had good compression. And I confirmed there is a spark.

Of note, I did notice that as I repeatedly tried to start the engine water pressure would build in the wand. And the pulling would get progressively harder. The fourth pull would be the hardest. The next one would be much easier and the sixth pull would get the closest to starting with the right amount of blueish smoke coming out of the exhaust, but it just wouldn't turn over.

Not sure if this has any baring on my starting problem or not, but I had played with the unloader valve when I mistakenly didn't have the crankshaft key in place and was solving for lack of pressure.

Does anyone have any idea what I should check next? I like solving puzzles, but this one might drive me to an early grave!

Thanks in advance for any and all advice.

-Trevor in Austin

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The Specialist said:

Quite a story, but if it is the model that I am thinking of, the pressure pump is bolted on the bottom of the engine. The thrust washer (which is a bearing) in the top part of the pump (where the crank shaft hooks on to, is worn out. You have to replace that thrust washer. A local bearing supply shop will have those, and they are not too expensive.

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DTWinters said:

Yes, my post got too long. Thanks for getting through it. I have copied a pic of the old gal.

Your kind advice sounds like the fix for why pressure wouldn't build and/or why oil is getting everywhere.

Would this thrust washer have anything to do with the engine no longer starting?

Spending another fruitless 45 minutes on trying to get it running, I noticed the throttle on the carburetor doesn't spring back when the on/off lever is turned to off. Whatever spring is on the other end of the connecting rod that goes back toward the rear of the engine (in a hidden spot) has lost its pull. But, I would think that would only effect stopping the engine, not starting it.

Thanks again for any and all help!

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The Specialist said:

If you are building up pressure on the pump while to start it, yes it will prevent the engine from Starting. In looking at the top of the carb, there is a rod that hooks onto the carb close to the engine block. This is your govenor rod. This is hooked to the govenor gear in the crankcase. If you look into the venturi of the carb, you will see that the butterfly will be wide open. When the engine starts, the govenor will move it to an almost closed position. When you bring up the revs by moving the lever, it will pull on that rod, so hence you get faster RPM's. I would get the new thrust bearing and seal first, then you should be able to start it. I have this come into the shop last week here in the U.K. and once I changed the thrust bearing and the seal, all was good.

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bertsmobile1 said:

Try some starting fluid ( carb cleaner is better ) down the plug hole.
And by a little I mean very little. Most will spray it for 30 seconds and then the excessive liquid fouls the plug.

Leave the air filter off.
Once it fires give it some short shots of fluid down the carb throat.
If you can not keep it running for around a minute like that then you have a timing or valve problem

If you can keep it running like this you have fuel supply problem

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DTWinters said:

What does it mean if I added six seconds worth of carb cleaner in through the plug hole, pulled the starter cord 14 times before a small backfire compression happened with smelly gasses escaping from the carburetor? Four pulls later a same small compression happened, but the engine was never close to starting.

I did go ahead and open up the crankcase again to have a look around. The timing marks were properly aligned and there were no signs of obvious damage.

Unless someone has a golden insight and easy fix for this challenge, I'm done with this machine and will focus my energy on finding another power washer on Craigslist or a retail shop.

I'm very open to suggestions for a decent gas power washer that can be bought for USD$400 or less.

Thanks for everyone's help as I worked through this annoyance.

-Trevor in Austin

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