Keith

Symptoms

• Starboard engine was always a struggle to start cold or hot;
• It was always rather hard to get it to crank, but the longer I held the key on, the more likely it was to eventually build up enough power to crank and start.
• But now I turn the key and just get a click.

There doesn't appear to be a slave solenoid or starter relay. Merc 0W335xxx
Pressed 50A circuit breaker, and also checked to ensure power to both leads.
Battery is 12.4v to 12.5v
No related error codes found
The wires from the 50A circuit breaker up by the PCM panel disappear into a loom and route back behind the motor down to the starter.

Is there a starter relay/slave solenoid on this 496HO, Merc 0W335xxx?

If not, I'm assuming I have a bad starter. What else could I be missing?

AllDodge

iTrader: (1)

Yes you have a start relay and it looks like the rest of the relays (MPR and FP) on the motor (item 5).

https://www.mercruiserparts.com/bam/...31826/11746/30

Keith

Thanks AD. I saw those when I was in the bilge looking parts up but they are identified as RELAY ASSEMBLies for Mechanical Throttle and Shift, or same for digital. I have mechanical, 2005 stuff.

The wires from the 50A circuit breaker disappear into a loom and go back behind the motor down to the starter. I'll add this to the original thread.

AllDodge

iTrader: (1)

Digital or mechanical use same relays, the digital just has more relays (appears only on more)

The start relay will have Yellow/Red wire on it

Keith

I'll see if I can get down there tomorrow to look. Is there any way for me to test the the relay, a way to jump it?

AllDodge

iTrader: (1)

Here is the relay


Pins 85 and 86 energize the relay. When your key is turned to start, power is applied to the small yellow/red wire on one of those two contacts. The other side of the coil goes to ground. So remove relay or turn it upside down and connect meter probe.

Contacts 30 and 87 pass power from the 50 amp breaker (red/purple) to a larger gage yellow/red wire which goes to the starter. There should always be power on the red/purple and will only be power on the larger yellow/red when relay is energized.

If power goes to the coil (smaller yellow/red) contact but does not crank the starter. Remove the relay and use a piece of 12awg wire or such to jump across contact 30 and 87, the starter should crank the motor

Keith Atlanta

I had a similar issue. It was the slave. The slave solenoid is right by the ECU and 50 amp breaker, its the only solenoid on the top of the engine. Turn the key on and touch the two big poles with a screwdriver, you will know what it is in 2 seconds. Two months ago I had the same issue, it was the starter solenoid. It will spark but its nothing to worry about.

Verify it and make sure the battery terminals are clean. The 496 is very grumpy if the terminals are even slightly corroded. The fully charged battery is key too but it appears you verified 12.4 volts.

Also, pull the kill switch and verify its not grounding out.

Hopefully its something easy and not the starter.

Keith

Keith Atlanta - I'm familiar with the part in the photo, only because I replaced them on my other boats over the years. Apparently my serial number series does not use that old style. I couldn't find it anywhere on the engine, and the diagrams don't show it.

I ordered a replacement relay AllDodge recommended, and need to get back down to the boat on Friday to have another go at it. If I don't report back, it means the regular shrouded relay with the yellow/red wires was the problem.

VPelliccia

I had some trouble starting and after some work found the following. Low Fuel pressure - 35 psi vs the expected 43psi. A contributor but not the largest issue.
After fixing the fuel pump I replaced the IAC and bingo - that fixed it. The IAC's are for a fuel injected engine the equivalent of the Choke (Air Flow)! The ECM pulse longer for the gas.. But the IACs do not throw many codes. They will only throw codes for shorts and opens.. In any case, this was the culprit on my 496 MAGs.

Keith

As a final report, it turns out it was the starter. Thank you AllDodge for pointing out that on some of the 496HO motors there is no legacy style slave solenoid/relay.