F 115 fuel system issue

[captron904]

I have a 2011 F 115hp 4 stroke. Boat is run 4-5 times a week (fishing charters). Recently started having a fuel related issue. Motor fires up first thing and idles and runs great every morning. After running and fishing few spots, the motor will start fine but will stall out once i put it in gear, just like its running out of gas (which it is) I've noticed the fuel primer bulb soft. so after pumping the ball a few times the motor will idle and run normal. Problem seams to show after motor has heated up. No problems running at any rpm, just after being shut off 30 minutes or so. Any ideas? Thanks

[99yam40]

does that motor have a fuel cooler that water flows thru?
if so maybe it is not cooling properly.

if you pump the primer before restarting will that stop it from stalling?
if so make sure the lift pump is running as it should to keep the VST full

[captron904]

Thanks!
I believe it has a fuel cooler. And if i pump the primer before starting it DOES idle normally without stalling.

[99yam40]

I am not sure how, but you need to find out if the lift pump is coming on when you turn the key on.
maybe someone else will drop in and help .
I am not sure if that pump runs at key on or not, seems like it should.

if the motor is getting the fuel too warm the VST may boil away most of the fuel while sitting after running is my thought.
So something has to fill it back up.

And make sure the water passage thru the fuel cooler is open and getting flow thru it

[captron904]

Thanks!! Good info!

[DennisG01]

The way I'm reading your first post, it sounds like the issue is with the bulb, fuel line and/or tank/vent. Since you noticed the fuel bulb getting soft, I don't think that has anything to do with anything on the engine?

-- When this happens, drain the VST tank to verify there is no (or little) fuel in there. If so, continue with diagnosing the fuel supply (what I mentioned).

-- First thought is that the bulb is allowing the fuel to drain back to the tank

[captron904]

I replaced the bulb, heading to the ramp now.

[captron904]

Update: New fuel bulb, but same problem. Can get a faint smell of gas while motor is off, so I wonder if its the VST or cooler? Maybe some type of needle check valve?

[Keithbaja]

Use a portable fuel tank hooked direct to primer bulb... I can't count the 100's of fuel and idle issues I've fixed due to bad/incorrect fuel line connections...

[DennisG01]

Update: New fuel bulb, but same problem. Can get a faint smell of gas while motor is off, so I wonder if its the VST or cooler? Maybe some type of needle check valve?

Did you try draining the VST to verify that it was empty?

I'm still thinking the issue is on the fuel supply (boat) side. I was going to initially mention using a portable tank plumbed direct but your post sounds like the issue happens after quite a while of running? Might be a little inconvenient to use a portable tank for that long - but a couple jerry cans of fuel to refill along the way might be the solution.

Could be a failing (internally) fuel hose... stuck AS valve... clogged vent/vent line. An easy way to check if it's a venting issue is to take the fuel cap off.

But... a portable tank plumbed direct to your engine eliminates everything on the supply side.

[captron904]

I didn't try draining the VST, not sure I know how to. The portable tank is definitely a good idea. I"ll probably try that this week. Issue happens more as I run from spot to spot throughout the day, seams its more prevalent as the the motor heats up during the day. Weird thing is that after fishing and loading the boat on the trailer, sitting overnight and launching the next day, no problem. Its almost like the motor cools off and somehow no issues until its hot. No issues at all while running, only after being off for 30 plus minutes upon startup.

[DennisG01]

On the bottom of the VST tank is a drain screw that you can remove with a simple flat-headed screwdriver. It's pretty noticeable once you look. Have a small catch can/bottle ready (a glass spaghetti jar works well). Save the drained gas and set it aside. Come back after an hour or so and look at it. Take a picture of it and post it.

[ausnoelm]

If the primer bulb is in fact going flat, then your very first test (as mentioned) is another tank, complete with fuel line and primer, the bulb going flat is a restriction between the primer and the tank air vent! That said, can you confirm the bulb is going flat, not just "soft"

[99yam40]

he said if he pumps the primer bulb before restating it does not stall.
also it is very hard to pump a ball that is flat.

apparently, he has not even checked to make sure the fuel cooler is getting flow either.

[captron904]

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