I've Got Gas, I've Got Gas!!!!

I think in any household, to have a grown man running around yelling "I've got gas!" would only bring looks of disgust in some and fear in others!!  Luckily, this topic has absolutely nothing to do with my colon function (but it's good, thanks for asking!) but rather the fuel systems on not just my boat, but most boats in general.

This past summer I was experiencing that bog in the motor, and then it would quit.  The motor would start fine, would run fine at low and high rpm, until it warmed up.  Or at least I deduced that's when it didn't like to run, once it was warm.  The first thing I check with such an experience is the primer bulb, and on most outboards, fuel injected or not, there is a inline primer bulb.  Mine "seemed" to be fine, you could hear the gas slurshing through it when it was squeezed but it didn't stay real hard like its supposed to when the system is primed up.  So, the investigation began, and this can sometimes be a veryyyyyyyyyyyyyy   lengthy process.

When I first got in the boat, I primed the bulb, I've NEVER had to do this with this Yammy, never.  I would then proceed out onto the lake, do a good 10 minute run somewhere and stop to fish.  After an hour or two or fishing I'd crank the boat up, head to my next spot, and blaaaaaaaahhhhhhh, the motor would quit.  Check the bulb, right empty.  Squeeze the crap out of it and the motor would fire up and away I'd go.  There would be no problem as far as it backfiring or intermittent running whatsoever when the motor was working, it would just run out of gas and quit.  This was quite un-nerving the one day it happened as I was flying by everyone and coming towards the first marker here on Shu.  With other boats behind me also throttled up its not the time to have a fuel problem but, that's exactly when the motor chose to quit!  Needless to say I was the target of some foul language as the other boats I passed buzzed by me but whatever, you get used to that after a few years in the RCMP!

My search began on the Internet of course, several forum's that I always go to for advice and research.  Unfortunately when you get 10,000 others diagnosing your problem, you usually wind up with at least 5000 suggestions!  In my mind (which is dark sometimes) I had already eliminated the primer bulb, so moved on from there.  I have a different fuel setup than most boats of this size.  My fuel line runs from my tank to a water separator/ fuel filter, which then splits, sending one line to the kicker, which has its own small inline filter, never ever had to change one of these.  The second line from the main filter then passes through my GPH (gallons per hour) meter, no filter there, just a whirly gig and laser that measures fuel.  From this apparatus, it then goes to the main motor which also has a water separator/fuel filter, then to two mechanical fuel lift pumps, then to two more inline fine screen filters, then to a VST (vapor separator tank) which houses the high pressure fuel pump that supplies fuel to the fuel rail and then to the fuel injectors.  Oh, and there's a filter in the high pressure fuel pump as well.  How's that for simple!!  Let me put it this way, if you can keep your fuel clean right from when it comes out of your tank, you've solved 99% of any possible problems with dirty filters along the way, that's why I have the system I do.

I started at the wrong end of the problem, having a look at the mechanical lift pumps first (photo) advice from the Internet!).  On my old F8 Yammy that had 5000 hours on it, the lift pump (photo) failed, and barfed fuel into the motor.  There is a rubber diaphragm inside the pump, and it wore out and leaked, and hence the fuel in the motor.  Was pretty obvious because when you checked the dipstick the crankcase was overfilled!  On two stroke motors which use similar lift pump, it would flood the motor sooner and stall it, because it does not have the crankcase with oil in it.  On my big motor there are two lift pumps, so I took them apart, my rubbers looked good, so I cleaned them up and did some testing while the motor was running, using a vacuum/fuel pump gauge.  Unfortunately my old gauge didn't have a scale that matched todays fuel pressure and when I was testing the two pumps the readings were right off the scale, which was a good thing!  These pumps were fine, so I started to backtrack from there.  I checked the factory installed water separator/fuel filter by simply bypassing it and running the motor out on the lake.  Sameo problem, motor still died from lack of gas.  I then disconnected the GPH meter and ran a bypass, sameo thing, motor died.  Next was the after market filter, I bypassed it and the motor still died.

After more internet research I found out that there is a anti flow back valve (in the above pic, under the bulb) right at the gas tank, the similar kind of valve that is found in the primer bulb.  The reason for it being at the tank is in the event the boat sinks, this valve is always shut off/closed when the motor is running.  There is a small ball bearing in the housing and it is held closed by a small spring.  When the motor starts and sucks fuel, the ball opens up and lets fuel out of the tank.  Motor turned off and no sucking, the ball closes and no fuel is let out.  I'm not sure why a tank would have this when I already have a check valve in place with the primer bulb so, I simply discarded this valve, all that was required was a new brass fitting to go into the tank.  I have no idea if it was faulty, the ball and spring seemed to be working but then so did the primer bulb, and after water testing without the tank valve I found I still had the problem.  So, what's left, that fricking primer bulb that "seemed" to be working right from the start.  You can't repair them, and I found them at Crappy Tire for a crummy $10 so put a new one in.  The result?  Problem solved, but I certainly learned all about my fuel system!  It's the old KISS principle, keep it simple stupid but, I figured I'd covered the bases all along the way, its just that with some parts you can't simply tell if they are working or not.  I even had the old bulb off and tested it by squeezing it pumped fluid into a container, it worked great!

The primer bulb is the most simple piece of equipment on the boat, for what it does.  It blows fuel towards your motor when squeezed, and when you let go a check valve in one end stops that fuel from coming back, but a check valve (photo) on the other end opens and lets fuel into the bulb when you stop squeezing.  Repeat the process over and over again and it fills your carb's or VST tank with fuel until you can't pump any more and the bulb gets hard.  Now, theoretically it should stay hard (that's what they all say!), or at least not get soft (mind outta the gutter!) and lose fuel.  This is what it turns out was happening with mine. 

The one check valve on the fuel tank end was not staying open when the motor was running a higher rpm, so the motor would suck all the fuel out of the system until it finally died.  When I went to prime the bulb, it was totally soft, but squeezing it opened the faulty check valve and again allowed fuel to flow through, as though it was working properly.  Learning experience, I've never had a bulb fail before but I guess after 10 years of not being squeezed it felt neglected or something.  Does this apply to wives??????  That'll be a different story.  My suggestion, the primer bulb is certainly cheap enough, replace it every 5 years and be done with it!!