[GaryDoug]

As I got no maintenance schedule information with the boat, I set about to update it all and started with oil change and fuel filter change. The oil change was uneventful, except that I did use the Quicksilver oil change manual pump and it does leak oil around the rubber end caps if you push on them too much. Otherwise it went ok.

The problem occurred after changing the fuel filter. I followed the instructions in the Mercruiser service manual to the letter. But afterwards when I started the engine, it only ran about 10 seconds and stalled while the alarm beeped several times. I still do not know what the alarm was telling me. After a few more tries, it would not start at all. I posted in another forum (with a very fast response time) about the issue and was told to fill the filter with fuel before installing it. That worked and the engine ran ok after that. It doesn't explain why there was no such directive in the manual. It would appear that the large volume of air inside the new filter was taking a huge amount of time to purge while cranking. Can I assume that filling the filter is standard procedure for all you guys?

While studying the issue, I realized that on an EFI or MPI engine, there is no purge path in the fuel system for the air except while cranking, when the injectors are opening. But even then the purge rate is very slow. In this boat, there is no return path for the fuel to the tank as in some boats and cars. And a carbed engine could purge the air through the carb's float valve. I wonder if the ignition/pump cycling might purge the air if the Schrader valve core was removed in order to provide a path. Any idea or opinions?

[Hudson River Steve]

Totally normal for the engine to die or at least stumble after changing the fuel filter. I do not fill the new one and have never experienced a no start condition afterward.

Sent from my XT1254 using Tapatalk

[GaryDoug]

Do you advance the throttle to start after replacing the filter?

Perhaps this isn't a problem for you because you have 8 injectors instead of just 2.

Here's the conversation on the other site: Serves me right for doing the preventive maintenances - The Hull Truth - Boating and Fishing Forum

[Hudson River Steve]

No, I do not advance the throttle, just let it idle. It usually dies once then restarts and stumbles a little for a few seconds then smooths right out. Maybe as you suggested it is due to all 8 injectors...and the heavy flywheel on my 7.4MPI.