Outdoor Power Equipment and Small Engines - B&S 5hp problem

Ok here we go. I have a pressure washer with an Ex-Cell 1500psi pump and 5hp Briggs motor. Have not used it for a few years. Cleaned out gas tank, rebuilt the carb. Runs great for about 15 - 20 minutes. Cleaned out tank once more, and carb, bought new gaskets again, reinstalled everything same problem. Used a tank from a generator that I know is clean, same problem. After 15 -20 minutes of use, motor starts to, slowly but sure, become weaker and weaker, tried adjusting carb slowly as it happend, nothing worked. I noticed that as I turned the idle mixture screw IN, even to the point of fully in, it did not affect the motor as it continued to run. Set it again and again to 1 1/2 turns from seat and began over. Always the same outcome. I did notice that once it began to become weak and surging if choke was set to half way it ran great for a short time then weaker, more choke runs better but not what it should but will keep running.
B&S model# 133432

Sounds like the fuel cap may not be venting, try running it with the cap loose. Have a good one. Geo

been there done that :wall: thanks

I have tried all the basic proceedures from fuel cap venting to re-cleaning and re-setting carb adjustments. Im starting to think maybe a valve problem?:coffee:

Did you replace the fuel lines/filter/shutoff valve/whatever is between the tank and carburetor? It does sound like a fuel starvation issue.

cheese, I read your recommendation this a.m. took tank off, opend the shut off valve and noticed a nice steady flow of fuel. I blew out line from shut off valve to carb after I removed that as well. No restrictions. I decided to remove the tank and fuel line from a generator I have and conected this to the pressure washer. I have been connecting the washer to garden hose while running the engine so not to burn the pump, with wand unattatched. Seems like engine ran great once again with choke set to run for about 10 minutes then it began to surge high and low. I set the choke just off the run setting and engine smoothed out nicely and ran nice for about 30 minutes. I decided to replace this tank with the original tank and shut off valve and original molded line from shut off valve to carb. Once again ran great with choke set to run for about 20 minutes. I connected the wand so that more of a load would be placed on the engine. After what seemed to be about 15 or 20 more minutes it started running rough again, shurging, I set the choke again slightly off the run setting and it began to run nicely again. I dinked around with turning wand on for quite awhile then off for a short bit then on again. Ran nicely. I did notice, however, that while I was moving choke to run that it had a bit of slop in the choke shaft. Now when I rebuilt the card, the kit came with a felt seal for the shaft. I did not install this because the choke valve itself in not of the screw on type. It has 2 small tabs on both sides of the valve to hold it in place to the shaft. I could not figure out how to remove it without damaging either valve or shaft or both. So, seeing how if I set the choke just off the run setting it ran rather nicely now, I reset the adjusments with choke at this location instead of completely on run. I think maybe there may have still been a restriction someplace in the carb that may have finally worked its way through, or perhaps even a bit of water. Not sure how or if I should even attempt to install the felt washer seal on choke shaft seeing how I think its running nice now.Your opinion?
B&S parts numbers:
Choke Valve:224783
Choke Shaft: 495651
Choke/Throttle Shaft seal and felt washer: 633 & 633A

If you're running it with the choke slightly closed, then there is still a carburetor restriction. The felt washer won't effect that. I wouldn't be worried about it, but you can put it on if you want. You'll have to grab the choke valve with pliers and pull it out to get the choke shaft out.

thank you cheese, I think right for now Ill let it be and hope for the best, it is running 100% better at the present time, so Ill hope for the best and see.