engine overspeed

I finished rebuilding the power head on my 2000 mercury 225 EFI after a melted #2 piston, started the motor and it sounded good, I shut the motor off after a few seconds and decided to take the injectors out and test them with a 9 volt battery, all were functioning properly. I reinstalled the injectors and started the motor again, it fired but went to full speed imediatelly it will not slow to idle, not linkages were moved. Where is my problem?

Re: engine overspeed

No idea about that engine nor what you did in testing....procedure. Butttttt

WOT with no control, and having touched nothing else tells me that your injectors are jammed full open. You did it with your 9v battery test. Nothing else makes sense if you told us the whole story. Is this a standard procedure for testing injectors? Where did you come up with the value 9v?

HTH

Mark

Re: engine overspeed

My mercury repair manual stated to use a common 9v battery and connect leads to listen to the solonoid pop open, I did, and with the solonoid open I used an air line and fuel to blow through the injector at 30 psi to test the pattern could I have maybe damaged the nozzle? I took the injectors out another time to see if they were closing and with no voltage the solonoid was closed.

Re: engine overspeed

I have zero experience with your motor but my manual (SELOC) covers that model. The fuel injector test procedures say either to use (1) the Mercury DDT connector with the special tool or a special software equipped PC or (2) a DVOM and check the resistance through the injectors. Does NOT mention applying voltage with a 9V battery. Will send you that page from my manual if you are interested. Send me a PM with your email address. Good luck.

Re: engine overspeed

your test method is not reccomended, its possible to have forced debris into them.
open the throttles fully, remove the airbox, turn the key on, look for dripping injectors while the pump is priming the rail.

the test is rather meaningless without a flow meter as each injector has a mesh screen that can clog and alter fuel flow. its a leading cause of lean burned pistons.
with the scan tool you can pressurize the rail and conduct a 2ms test and record the pressure drop of each injector. its not the best test but its all that can be done with the injectors mounted.
as the injector windings are rather fine and they are not desined to carry current for any length of time its possible they are damaged,