F 115 fuel system issue

[DennisG01]

I was told that if the motor is peeing, then the cooler is getting flow. Bulb not going flat, just soft.

You're referring to two totally different systems. "Peeing" is about water flow. When we're referencing the VST (fuel cooler), we're talking about... well... fuel

Please don't take this the wrong way as there is no malice intended... but if this stuff isn't in your wheelhouse, you might be best served to get a pro to look at it. The last thing you want to do is save $5 only to spend $10 later.

[captron904]

Got it, Thanks! Unfortunately I use the boat everyday and combined with my mechanics schedule, I'm unable to get it in the shop right away.

[99yam40]

I was told that if the motor is peeing, then the cooler is getting flow. Bulb not going flat, just soft.

I know very little about your motor, but I have read some fuel coolers can show a tell tail but not have poper flow thru the fuel cooler.
just saying it is something to check on.
taking some tubing off to verify should not be that difficult

[captron904]

Thanks! I'll check the cooler.

[ausnoelm]

Don't fall into the old "I read" I was told" "I think" you have to KNOW something is good or you're just stabbing in the dark.

[DennisG01]

I realized I was as clear as I should have been with my response in #12. Yes, it's two totally different systems... but both systems "could" be the issue.

The level of fuel inside the VST is a possibility (although, truthfully, I don't "think" that will siphon drain). But it would be good to verify that it is, indeed, remaining full of fuel. And it's also an easy way to check fuel quality.

Then there's the cooling issue which, of course, is the water flow. As noted above, though, follow (backwards) the pee hose and see where it goes and/or where it T's off.

[captron904]

Thanks guy's. Got my Yamaha mechanic scheduled for tomorrow. I'll post the results

[DennisG01]

Oh... hopefully this was obvious, but in post #21 I meant to type "I wasn't as clear".

[captron904]

Put the boat in the water this morning. Had my mechanic check the fuel pressures which are good. The fuel cooler is working as it should. The VST is good. Today the weather was cooler so I didn’t experience the vapor lock that I do when it’s hot outside. part of me is starting to question the integrity of the gas that I’m getting? I use ethanol free, but I’ve had the same problem a couple years ago, which I think was some bad gas. I get the gas at the same location every day. I know if I use regular gas with ethanol this motor really acts up. I replaced the fuel/water separator last week and the gas looked good tho. Next step is to hook up the remote tank and see how that goes.

[DennisG01]

What did the fuel look like when you drained the VST? Did you let it set for a while like we talked about previously?

Gas with ethanol in it should not cause a problem if it's fresh/clean and, especially, if you're religious about using a good additive like Startron.

BUT... since you didn't have the issue today, I don't think you're having a "supply" problem like I initially thinking.

[captron904]

Gas look clean. I have a picture, but I’m trying to figure out how to make the files smaller so it’ll upload.

[DennisG01]

Gas look clean. I have a picture, but I’m trying to figure out how to make the files smaller so it’ll upload.

Gotcha. No worries. If it looked clear, smelled like gas and there wasn't any separation after an hour, then the gas, itself, shouldn't be the issue.

[captron904]

Problem is more frequent when its hot outside. Once the engine cools down over night it starts and runs perfect until later in the day. Always runs great, but looses prime (air in fuel line) after engine is off 30 plus minutes, and is hard to start.

[99yam40]

Problem is more frequent when its hot outside. Once the engine cools down over night it starts and runs perfect until later in the day. Always runs great, but looses prime (air in fuel line) after engine is off 30 plus minutes, and is hard to start.

I thought you said, you can pump the primer bulb and it will start and run just fine after running and sitting for 30 minuets.

you still have no idea how much fuel is in the VST after you shut the hot motor down and it sits for 30 minuets plus.


If you can fill the VST up using the primer bulb to solve your problem,
then you need to find out where that fuel is going
and why it is not filling back up once you restart after a hot motor sittting for 30 + min

how did the tech make sure the cooler has good flow?

[captron904]

OK, let me explain one more time in detail. I use this boat pretty much every day. Recently, after launching the boat in the morning and moving from spot to spot. After the engine is off from anywhere from 30 minutes to an hour, it is starving for fuel when I crank it up. importantly, I can squeeze the ball to re-prime, the fuel line, and it starts fine after that and picks up fuel and everything is great until the next stop. It’s obviously more prevalent when it’s hot outside. We’ve pulled the coolant lines to the fuel cooler and an even ran string through it to make sure it was clear. Which it is. Running wide-open, idling, and everything else is perfect except for after it sits off for a short period of time when it’s hot outside.