2003 BF130 Fuel injection not holding pressure

[aguffin]

I am working on a neighbor's BF130 that he recently acquired, the boat had sat for a number of years and needless to say the fuel injection system is needing some work.

After replacing an inop high pressure fuel pump, all filters, and cleaning out the (new style) vapor separator unit the motor starts but has a very rough idle as well as high carbon outputs from the exhaust. The spark plugs will also carbon foul in just a few minutes of running on the hose. My initial thought is I have leaking injectors since when I shut the engine off and immediately remove the test port for high pressure I have no fuel pressure. (Imagine my joy to find Honda has to require their "special" test gauge instead of the one I use for Mercury, Yamaha, Suzuki, etc.... There is no AN4 fitting or Schrader valve on this unit)

All other fuel injected outboards I have worked on in the past maintain their pressure for some time, resulting in a spray of fuel when relieving pressure.

Is this just a Honda thing on the pressure or am I on to something here?

Any help is appreciated! Thanks!

 

[wrench 3]

I don't know for sure if it should hold fuel pressure but since they give you a procedure for relieving fuel pressure I'd say it's a safe bet.
A ruptured diaphragm in the fuel pressure regulator would dump fuel through the vacuum line to the regulator and over fuel all the cylinders when running.

 

[aguffin]

Thank you, had not thought of that angle, can crank it up and see if there is fuel in the vacuum line. I do have the "official" fuel pressure gauge arriving Tuesday as well, if there is an issue with the regulator I should have a wacky pressure reading.

 

[wrench 3]

I'd be interested in hearing what you find.

 

[aguffin]

Ok, so I removed vacuum hose and pressurized the system as well as started motor, no fuel leak from hose. I then removed fuel rail with injectors still attached and held my breath and pressurized again (you can't do that with a Yamaha, don't ask me how I know) no leaks from injectors. I then plugged the regulator return hose and started, after shutting down there was residual pressure! I'm really at the point where I'm waiting on that pressure gauge to arrive so I won't be throwing parts at it blindly. My guess is the regulator.

 

[aguffin]

Well dagnabbit! While waiting for the other parts to arrive I pulled out the compression tester and checked all 4 cyls....

130lbs on each, this motor is tired!

That could explain the carbon fouling, now my neighbor has some decisions to make, I'll check the valve adjustments and if everything is OK there I might suggest he throw a hotter plug in there for the season while he saves up for a rebuild.

 

[wrench 3]

If you're loosing all pressure through the regulator it's definitely bad.

 

[aguffin]

Ok, so finally got gauge in and we did have a bad regulator, 70 psi and when motor was shut down it immediately went to zero, replaced regulator and now have a happy 40 psi and after shut down it takes about 5 min to lose the pressure. More in line to what I normally see in other motors. I also rechecked compression after a good warm up period and it seems to settle around the 150 mark, not spec but not horrible either. Might suggest a few heavy doses of Yamaha Ring free or Seafoam to knock out the built up carbon from the injection issue as I scoped the cylinders and see a good coating on the tops of the pistons. Thanks for the help! At least my neighbor bought me a Honda gauge to add to my shop equipment...

 

[wrench 3]

Bonus! I'm glad you got it sorted.