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2006 25hp 4 stroke will crank, won't run

E

evensplit

New member
I am out of ideas, and think I have the problem figured out, but could use some backup. 2006 Mercury 25hp 4 stroke. Good battery. Turn key, no beep and no HP fuel pump running. Motor will turn over but won't start. No fuel pressure at fuel rail. Mechanical fuel pump works fine, HP fuel pump works with direct wire connections. New fuel pressure regulator. Good spark. Motor will start and run when fuel is introduced via the intake manifold. I have troubleshot everything I can think of and have replaced the cheap stuff- and I'm down to a bad ECU as my next guess. Any input or ideas would be greatly appreciated!
 
Sounds to me like some sort of break in your wiring system, Get an AVO meter and check continuity between your ignition and the fuel pump, check if there is a fuse in line. You should have a beep, maybe the problem lies in the ignition switch itself, this can also be checked with your AVO meter. best of luck..
 
Thanks for the reply! I've checked the ignition switch and wiring, and as best I can tell, have good continuity up to the ECU. I'll run through it again just to be sure.
 
Ignition switch checks good, and I have good continuity up to the ECU - no power from ECU to HP fuel pump with key on. Gotta be the ECU right? Other ideas?
 
Do you hear the HP fuel pump run when the key is first turned on? I had to replace the one on my 40HP a year or so ago when it locked up. Check to see if it is getting power for a second or 2 when the key is first turned
 
Thanks for the reply!
No power to the HP pump, nor am I getting the "beep" when the key is turned on. Pump has been tested and is good.
 
Check the lanyard kill switch. I tried a few things with my 40HP and the fuel pump doesn't run if the lanyard kill switch is tripped when key is turned on but works fine with the switch in normal position.
I didn't check for spark with the kill switch tripped but they might just kill the pump and not the coils
 
Thanks! Ignition switch and kill switch are my next subjects. They check fine, but so has everything else and I'm out of ideas. I've had some strange boat issues over the years, but this one is totally baffling.
 
Thanks for the reply!
There's only one fuse on the engine that I know of - a 20amp for the starter - unless there's something that I've missed.
 
PROBLEM SOLVED!!! After almost a year of tracing wires and replacing parts. I bought a new battery. That's it. A new battery - even though the old battery was only 2 years old, took and held a charge like normal, and tested fine. She now starts and runs like a champ.
 
Well, Well. that's great news. I think we all presumed that the battery was in good order so there is a lesson to be learned here.. Check quality of the battery first.. Good luck with your boating..
 
Eric Hoare said:
Well, Well. that's great news. I think we all presumed that the battery was in good order so there is a lesson to be learned here.. Check quality of the battery first.. Good luck with your boating..
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I've been boating and working on boats for almost 40 years, and I'll never say that I've got them figured out. They make me feel like Clark Griswold's cousin Eddie... "Falls in a well, eyes go crossed...kicked by a mule and they go back straight again...(shrug)..I dunno...."
 
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