I have a boat
with two Yanmar
4BY3-150 turbocharged diesel
engines. After cruising normally for an hour or so, I was very near my dock
just above idle speed and the port engine
sputtered and died. It cranked strong but would not restart.
Suspecting a fuel
issue, back at the dock
, I checked the primary and secondary fuel
filters (they looked good) and changed them out for new. I bled the system according to the instructions (repeated key on 10 seconds, key off 5 seconds, I'm not 100% certain as how this bleeds the system). Still cranks strong but no luck in starting.
I have the benefit of having a 2nd identical engine
(starboard side) that I can use for comparison purposes, that engine starts and runs fine.
The fuel flow for each engine appears to be:
It's own tank -->
Primary Fuel filter
low pressure fuel pump
secondary fuel filter
high-pressure fuel pump
An ECU controls each engine. Fuel pumps are supposed to get power when key is turned to ON. Fuses/relays/etc checked in the ECU and are OK.
- There are no bleed screws and no reference in the manual to alternate methods of bleeding other that the "key on/key off" process but I cracked open the "fuel out" from the secondary fuel filter and the moment I did KEY ON, it sprayed fuel out very strong. So I know the fuel flow is good all the way through the secondary fuel filter, and obviously the low pressure fuel pump
- Both engines sound identical to me upon KEY ON, you can hear the fuel pump(s).
- I cracked one injector slightly on both engines (they are hard to get to and I didn't want to remove the manifold) and fuel leaks
out very slowly when cranking each engine, the amount of fuel leaking out of the good and bad engine looks the same to me.
- On the ECU, you can feel the fuel pump
relay click and a volt meter shows that the wires are getting power upon KEY ON. Someone suggested there might be a solenoid somewhere but I cannot find it (except for the relay on the ECU) and the service
manual makes no reference to it.
I am at my wits end on this issue as I have been unable to use the boat
for weeks. I am in Florida
and although there are a few Yanmar
mechanics around, they takes weeks to come out if they show up at all.
I'm wondering if anyone here has a 4BY3 engine or one of their cousins in the BY series and has any suggestions as to what is the problem and solution?