282 BR had hard time starting then shut off

FamilyTruckster

Over the weekend (temp was upper 90s with high humidity) my 282 BR with the Mercury 6.2L MPI cranked and cranked but wouldn't start.  Volts were fine.  After bumping the switch to 'on' about 10 times it started.  It ran at idle for 5 minutes or so then as we passed the no wake zone I throttled up and it died.  It had a hard time starting again, so I lifted the engine hatch some, bumped the switch again and then it started and ran fine for another 20 minutes.  

We parked, ate and swam for about 3 hours.  When we came back to the boat it started fine and ran for about 20 minutes.  Then I tried to give it more gas and it died again.  This time we couldn't restart it and got a tow back to the dock.

At the dock it started after about 30 more minutes of waiting but when I put it in neutral and gave it gas it would die.

A neighbor came over yesterday and checked the pressure at the fuel port.  With the key on but not started it was at 35.  When started it would drop to 28 and even hold at about 18 after a little bit of time running.  Is this the right pressure level?  Is it an indication of a bad or failing fuel pump?

Also, the fuel return line has been cut-off and crimped off.  Is cutting and crimpimg this off normal for a merc 6.2L?  Does it return excess fuel a different way?

Thanks for any help.

212rowboat

you're running out of fuel or you're pulling against a vacuum greater than the pump can defeat (and it ought not have to fight for supply at all)... 

the pressure should remain the same- the volume will change, yes, but the pressure should be precise no matter the rpm or load.  

a bad vent on the tank will disallow the pump free access to supply... a clogged filter will do the same.  a bad pump won't be able to keep up with demand at higher load and/or RPM... I don't know that the static pressure should be, but 35 sounds about right... any deviation from that means something is wrong. 

the return is something i don't know- but i think it's a coast guard thing that there is no return from the engine... it handles it from the cool-fuel module if i'm not totally wrong, and simply diverts the excess flow back to the supply side... 

Black_Diamond

I believe only diesels use a return fuel line to the tank. 

Handymans342

I had a return line on my old gas boat and I believe all gas fuel injected motors have a return line. 

212rowboat

Built in recirculating or pressurized return?  Huge difference. One legal, one not. 

Black_Diamond

No return line on my 350 MAG MPI. 

FamilyTruckster

Thanks guys.  The line appears to me to be built in.  The neighbor that checked the pressure is a retired diesel mechanic.  He said that he wasn't sure on boats, but if it were on a car it should have the return.

I am just trying to figure what to tell the techs over the phone tomorrow.

I have heard vapor lock, but it just doesn't seem right to me without some other failure.

212rowboat

Bad filter, blocked vent, failing pump, in that order of likelihood.   

FamilyTruckster

Thank you.   This has been frustrating and a bit embarrassing getting towed back and then swimming or to the dock the last 100 yards or so...