This one has me scratching my head

A couple months ago wile running down he bayou the engine slows down and kills. I checked the tank, vent was open, plenty fuel, checked both conections ok, the bulb was empty, pumped it back up and no more problems. Fast forward last week same thing happened, after closer inspection of the conection on the tank a cracked O ring, I replaced it. Next trip the bulb wont stay full of fuel, the motor would run till the little bit of fuel ran out in the hose, changed the bulb. I ran the motor at the house with the ear muffs and still have the same problem. On my after market tank I am able to remove the fitting that goes down in the tank and nothing obstructing the suction. I borrowed a nabors fuel hose and will try that tomorrow. Oh its a 1999 Yamaha 25 hp 2 stroke the engine has run good until this happened.

If the borrowed fuel line doesn't work take the fuel line that goes from the fuel pump to the carbs off at the carbs and put it in a container then try to start. Fuel should pulse out (6-8 lbs pressure I think) if the pump is good.

I had a very similar problem on a 2018 Honda 115. Ran out of fuel at full throttle. Pump the primer and it would run fine. I ran a portable fuel tank straight to the motor for a month with no problems. Hooked it back to the boats fuel system and problem returned. My selling dealer looked at it for 6 weeks and never found a problem. After the trip to dealer still had the problem. Then without warning problem stopped. I have run my motor hard for last 65 hours with not a single issue. Go figure.

I have a 1994 yamaha same thing happened . Switched tanks. Cheched the hose primer ball, the "filter with screen?" Opened up the pump on the side of the block had fuel in all the rite places. Best we could come up with was water in the fuel or a speck of dirt. Whatever it was it worked itself out after all that monkeying around.

I have had hoses to collapis inside. If it is a old hose it may need replacing. Another thing is to make sure the top on the tank is loose so to get air as it will cause a vacuum and will not run.

I tried the borrowed hose yesterday and had no problems. I'm going to the boat store today and get a new hose.

I had the same issue at High Rock. The liner on the inside of the gas hose had dissolved and was clogging the line. Replaced the line and no more problems.

Chip -- did that fix the problem replacing the hose ---I thought it might not be the right size "o" ring letting it suck air

All the phoses built since ethanol came around have a plastic like liner inside and sometimes the colaspe and cause simular problem