MerCruiser MPI starting issue

[BillWilliams]

We have a new to us 1999 Formula that has a MerCruiser 7.4 MPI Bravo 3.

The engine has started with no issues until one time yesterday where it just wouldn't stay running. After several attempts and working the throttle, it did stay running and once it was running, there were no more issues.

Since we're new to the fuel injected engines, could this simply have been a gas issue where I need to turn the key on for a few seconds and then back off a few times to allow the fuel pump to do its thing before I actually tried to start the engine?

Thanks

 

[Sandy]

The procedure of turning the key just On while the pumps prime for a few seconds then Off, then repeat should only be be needed if the engines are being re-commissioned after a layup, Otherwise you should be able to just turn the key to On and listen for the priming pumps for that few seconds just once and turn the key to Start and have it fire up in a few seconds.... if everything ( caps, rotors plugs and plug/coil wires, filters, oil , flame arrestor, fuel quality , etc.) has been maintained . `

MPI engines should start quickly. If you run into a problem of no starting, listen for that priming sequence.
If you don't hear it , check the pump & relay & ECC/ECM fuses on the engine.
If you can hear it prime OK and you have good gas, in case an injector is stuck open and engine is "flooded" , try moving the throttle control all the way to WOT then crank( being ready to reduce throttle to idle immediately if it starts.)
This deactivates the injectors until it fires . But don't crank more than a conservative 7-8 seconds at a time ( & even less if voltage is low)and allow time for the starter to cool down between tries.

When I get a new to me powerboat , about the 1st thing I do is replace all tune-up parts and filters and oil and check RPM and timing & advance even if the timing is ECM controlled. On some MPI's , distributor cam retard angle must be set within +/- 2*, and can only be determined with an appropriate marine scan device and connector adapter. The scan device can also reveal many( but not all) other engine issues you would not otherwise be aware of. And it can quickly rule out good suspect parts.

If it takes more than 2 tries doing that, you have other fuel or ignition problems.

 

[BillWilliams]

Thanks for the information.