Mercury MX 6.2 cuts out
 

06' merc 6.2 with 435 hrs, runs good and then after 20 mins or so cuts out sounding the alarm, acts like the kill teather is pull or key turned off and right back on real quick, doesn't kill the engine.
Have Diacon software, NO faults detected or stored. By looking at the data only thing I can see or find is a voltage drop right before the hiccup occurs, voltage drops from 14.34 to 13.28 then right back up to 14.34. I've replaced the battery and checked battery cables. Any ideas??
Thanks Steve

Run engine with boat in water, or on hose. Move around every possible wire and connection. Mine did something similar once ended up being the # 7 injector plug.

This was while running in the water, ran fine on hose and was fine last year problem started first time out this year from winter lay up.

You have to pull, push every connection. It sounds like you are loosing power to your ignition system. You just have to do this while running.Find it and you will know, the engine will die. Could also be a crank trigger but do what I said first its free.

Check ground wire going to engine block. Also ground wire that goes to the fuse block.

Chris

Power from the battery goes through a small black 90A square fuse block onto the starter.It gets loose sometimes,all you do is tighten the nut &bolt .The ECM555 senses voltage drop and cuts the ignition out randomly.

Good to know, it is definitely something like that. Thats why no codes the ECM thinks you just shut it off.

By chance have you installed a newer distributor cap lately? Then noticed this problem? If so then try another newer dated cap.

No, haven't tried a new cap, have these had problems with the caps? It doesn't backfire back thru the intake like its misfiring just hear the alarm and a quick hiccup

Yes, lots of different problems with them style caps.

Just something different to think about is all.

The newest merc Cap and Rotor Kit part number is 8M0061335.

?, When you first turn your key on before starting, Do you get a beep from the warning horn as a test? If so try this, Hook up a digital multimeter to battery, start engine, read 14.34 volts turn off engine see if it immediately drops to 13.28 then turn key back on and see if horn beeps again. To test this theory quickly like, use the lanyard kill switch instead of the key switch. Your just simulating a possible ignition cut out event to help theorise on what's happening.

Like said above, shake wires with engine running, Also if you have the 10 pin rubber cannon plug between engine and boat wire harness (at engine side) shake it around really good + it should have a clamp on it set lightly. 2006 may have the 14 pin connector, They are not as much of a problem like the rubber plugs but you never know.

Good luck.

My 2006 with less than 50 hours on iit started going into guardian mode every time after about a mile of running early last fall. It will actually completely die but quickly restart if you are heavy on the thottle. Had the 555 read at the dealer and it said the fuel pump relay was the problem. Dealer never had one so I left and picked one up later at another place. Installed the new realay and the problem persisted until I stored it for the winter out of frustration. Right now I am waiting for the newest Diacom software to arrive so I can endeavour to diagnose and solve this myself. Any comments or suggestions would be greatly appreciated.

Are you getting an alarm before it goes into gaurdian ? If so what RPM ?

Yes the alarm sounds, the engine stumbles and you get the beep about every 2 minutes. Typically the RPM is in the mid 2000 range. The Smartcraft screen then shows an engine icon which goes away after shutting down and restarting. Oil pressure, water temp, water pressure, alternator output are all good. The boat will cuise and run for miles in guardian mode.

Guys, there is another issue that can come up for the 6.2's with Cool fuel system, putting the engine in guardian mode. Merc put a redundant filtering system on these for warranty reasons, I guess. There's a tiny s/s filter and "O" ring under the fuel regulator mounted on the cool fuel cylinder.Over time ,impurtiy builds up on this filter and spikes fuel pressure too high levels, dumping too much fuel into the cylinders. Had this problem and noticed fuel dumping out through the exhausts. My Rinda scan tool saved the code for fuel level too high for this. Also, I observed fuel pressure as high as 72lbs at the Schrader valve at idle. The primary fuel pump [ low pressure] has a filter before and the secondary [ high pressure] pump has a dime size s/s filter on the inlet. I removed the small filter that caused the problem with pressure spike [ return line] and it fixed the problem. From the pressure regulator, fuel goes back to the water separator and I think it's suffice to catch debris and easier to clean/replace than slumber down into the bilge ,dealing with the s/s filter.

Yes, check as stated above. Also check your regular fuel filters you should have two. And get a gauge on it for pressure readings. The 2000 RPM alarm is odd I thought the first one was 3500 other than the temp. and low oil.

Thanks for the tip. I change my fuel filters (#21 and #26) every season and never have had a problem you are describing but curious to check it out. Where is the s/s filter located (looking at the drawing) and is it possible to clean and re-install?

Under #10 ,not all of them have it mine is more like a screen. I think thats what is being talked about because I was told to check the as they clog.

The small s/s screen is #14 in the pdf graph http://www.boats.net/parts/search/Me...ler/parts.html

Interestingly, the larger s/s screen isn't shown in the graph for the fuel pump. It's inside the inlet of the pump past #6 fitting and #6 "O" ring. This screen wasn't removable when I had the unit apart so I just blown it clear with compressed air.The little screen is the one with a very fine mesh, hence the greater chance of fouling up.

Mine does not have the cool fuel system that is pictured. I have the original cool fuel return system that goes back thru the separator. There is only one small screen filter at the pressure pump and I believe it is clean because I had the entire system off the engine and appart when the fuel pressure dropped at the schrader valve and the engine died and would not start.

bump

To the guy with the 6.2 skipping.Over time the crank position sensor that is mounted right behind the harmonic balancer may get a little too close to the reluctor wheel due to the plastic cover warping a little over time. Take a # 10 washer and place it between the metal bracket and the plastice cover to space it out apx. .020.This fixed some of our 6.2 mercs. hf...

This is what it appeared to be, tightened and been all good since. Thanks for the tip. Steve

I'm glad it was a simple fix! Put a hose clamp on the main connector to the engine also!

Hose clamp on main connector to motor? Not sure I follow, unless that's suppose to stop it from moving and getting loose as a result

The 6.2 has two main connector/harness. One is a big round plug, power [ black ] that sometimes getting its way out.That's the one you want to put a s/s hoseclamp on tight.The blue cable [ for the ECM555] connector is more secure.

Ok thought I had this issue fixed but.......
I've tightend the battery terminals, connector at starter where the big fuse block is also checked main wiring harness for tight connection along with the 2 plugs on the ECM. I've hooked it up to Diacom software which gives no faults and it still sounds the alarm and the engine stalls for just a sec not enough to kill it, I've noticed today while idling around if I use the trim a lot it wants to do it more often, so I'm pretty sure it's voltage related, Ive replaced battery and the alternator is charging any ideas?? I've got both an ignition and fuel pump relay on order should be here tomorrow to swap and try, I've never noticed it cutting out past 3,800 RPM's only at lower RPM's in the idle to say 2,800 ish.

Wouldnt this show up on an engine scan as a crank sensor fault?? I'm getting no faults when I scan it, it does go into guardian mode if I'm at full throttle and then gives me over speeds codes, I'm sure it's because I'm at wfo when it has the issue, but no other codes tripped.
Replaced relays and problem still existis?? Ideas?? Anyone?

im having this exact issue. was this ever solved. my symptoms are identical

Change the rotor, or check it with an OHM meter. They are notoriously bad, they loose contact between the stainless steel and brass junction. Big GM problem, most GM car dealerships are aware of the condition as bulletins have been sent to all GM service departments.

i have had a few of these i just turn the dist a little bit and problem solved theres a few on here that could bring up a tech bulletin on this

Thread is from 10 years ago