Crank position sensor issue?

[pkennamer]

2016 Merc Pro XS 225 Serial #2B230775

So I repowered my boat about 5 weeks ago and motor has run great until last weekend (16hrs or so now). Motor ran fine until about mid day and when idling up to a hump it just died. I was close to where I was fishing so didn't even crank back immediately. An hour or so later when I was ready it leave it didn't want to crank, sputtered a bit and then finally ran fine. Went to weigh in and when I was idling in to the dock it died again and a solid beep alarm went off with a motor symbol on the smartcraft gauge (didn't crank back up). I carried to my dealer when they opened Tuesday morning and had it back Thursday. The mechanic said the only code it showed was a faulty crank position sensor. I asked what caused such a thing and he said he really hadn't seen that being a common problem so wasn't sure. Fished a few hours Friday and all seemed well. Fished Satuday and about mid-day I was pulling up to a spot and it died and alarm started going off. This time it never cranked back and I had to be towed by a friend. I text the dealer and he said they would call Mercury when I bring it back this week because there was obviously an underlying cause. Anyone have any experience with something similar? Although they seem to me minimal I'm very unhappy to have issues out of a motor with only 16 hours on it...the 2002 225 EFI I sold never left me stranded in the 12 years I owned it.

[pkennamer]

Anyone, Don opinion?

[JOE54]

have seen few too no crank sensor issues since early 2000 era like 01 2 3 , did engine have no spark or no fuel delivery ????

[pkennamer]

I really don't know. When I carried it in last week they said it started up and ran. The only code it showed was that sensor so they swapped it out. When it died Saturday it just cut off and when I tried to crank back it sputtered and the alarm sounded. Waited a while and tried again with no success. I am by no means a mechanic but the sound reminds me of a dirty fuel filter or bad gas on an old lawn mower.

[Savage]

Saturdays alarm should steer the technician in the appropriate direction, once the history is reviewed.

[EuropeanAM]

If indeed it was a Crank Sensor Fault (or a VR Fault), it may (or may not) be the crank sensor itself. Loose paint, loose flywheel, yellow plastic cap grinding around in flywheel/sensor, corrosion on the flywheel reluctor teeth, or damaged/missing/malformed teeth are also possible.

Be sure to get PRINTOUTS as described below, I'm happy to review them if necessary:

WARNING HORN "BEEPED"

[pkennamer]

Well, it has now died on me 3 trips in a row and won't crank back once it happens (had to be towed once, was near ramp other 2 times). After sitting from Saturday until Tuesday (wthe shop opens) it cranks right up but when it does on the water it won't crank, the alarm sounds (solid beeeeep), and the engine just sputters. Last week while in the shop they called Mercury and at Mercury's suggestion they tried a heat gun on the crank position sensor and couldn't make it cause the error, next Mercury paid them for an hour to take it to the water and they couldn't make it happen. The tech said he looked the flywheel over as well and couldn't see anything wrong. I take the boat out Friday and it runs fine that morning. Later after a mid day break it happens again that evening , thankfully I was near a ramp. At this point I'm very frustrated and told them not to give it back until they solve the problem. I don't know if it will help but my intentions are to call Mercury tomorrow and file a formal complaint. The dealer is also calling them requesting that mercury themselves send someone to work on it. Don, I'll work on getting the printouts, thank you for taking time to respond.

[pkennamer]

The only common event I can associate with this is that is happens randomly after I come off plane, every time it's happened was at idle immediately after coming off a run (on long, one mid, and one short), had good water pressure, temps around 125 on smart craft gauge.

[Savage]

Lets straighten out some common terminology.

Wont Crank = Means the motor will not turn any revolutions at all.
Wont Fire = Means the motor IS cranking (revolving), but wont start (fire).

Lets use this terminology going forward in this thread.


Now what is the battery voltage during cranking ?

Are you pushing on the throttle while trying to start the motor?

[pkennamer]

I guess you could say the motor won't fire, it will turn and sort of spits and sputters but never actually "hits" so to speak (almost sounds like it's being starved of fuel). I checked the fuel bulb and it was firm.

I bought a new 1000cca battery (duracell from Sam's) shortly after I got the motor, per my humminbird the voltage was right at 12.1 Friday afternoon. I had just sat down from a short run when it died and had made about a 7-8 mile run an hour or so before - also charged mid day while tied up to my dock.

I have tried pushing the throttle down, not pushing it and everything in between. There doesn't appear to be any difference, actually it doesn't even really rev the motor. Friday evening I was near a ramp and had someone take me to my truck at a different ramp up the river. I was back to boat within an hour or so and it sounded a little more optimistic about cranking but still wouldn't. I just took it straight to the dealer Saturday morning and didn't try to crank it but I would have bet money it would.

I could be imagining things but I really think the last 2 times it's happened the motor started sounding a little different while running and then when I sit down it dies.

[EuropeanAM]

See if you can get those printouts. The fact that you hear an alarm sound indicates there is a fault... the info is stored in the PCM's Freeze Frame History (just waiting to be used).

With the utmost of respect intended... until we look at that Printout, it's much like a doctor that plugs his ears during a patient's office visit.

[pkennamer]

Hopefully we've finally gotten this resolved so in the event that anyone else has a similar problem I wanted to post a follow up. After way to many of the incidents listed above the mechanic finally found a small tear in a gasket where the sensor plugged into the computer. They believed there was moisture getting into this small tear after a long day (only time I had a problem was all day trips) and causing the fault which shut the motor down. This gasket is built into the computer so Mercury instructed him to patch it with RTV Silicone, which he did. Thankfully the mechanic is honest and told me about the patch. Needless to say I was very unhappy about having a brand new motor patched up with silicone. After running it numerous times with no serious issues we believed the problem to be fixed but I was never confident it wasn't going to leave me stranded again (still had a couple of sputtering issues we believe were related to this). Finally after talking with a few of the right people Mercury agreed to change out the ECM on the motor. This seems to be a rare (possibly one of a kind problem) but thankfully Mercury decided to make it right.

[EuropeanAM]

Glad to hear they're getting you taken care of. Definitely very rare to see this problem (and there may be a misunderstanding about the "sensor"... sensors don't "screw into the PCM").

[OldTimer57]

No, but they do "screw with" the PCM. :) BTW is this really called a PCM? Or an ECM? What "powertrain" is their to control? :)

[Savage]

Yes, Mercury calls it a PCM....

Propulsion Control Module

[OldTimer57]

Nothing like overloading a well-known acronym. :)

[EuropeanAM]

Been called a Computer, ECU, ECM, and now PCM.

[OldTimer57]

Not to mention brain...