2005 XR6 150 cutting out

[jrh_67]

I have a 2005 XR6 150 that was running great earlier this spring but has now begun to cut out sometimes. It doesn't always do it but when I go fishing maybe the first run to a spot it will cut out and then when I leave that spot to go to another it will be fine or vise versa. It's not consistent at all but does it now about half the time. I don't know if it's related but it began after a long day running the boat and making it back to the dock basically out of gas running on fumes. I thought at first I just got bad gas but now after filling it with fresh gas I still have a problem so I replaced the fuel filter but it didn't help. It idles fine but as soon as you begin to plane out it begins to "stutter" is the best description I can think of. The motor is a 2005 XR6 150 serial #1B191100 if that helps any. Any help at all would be appreciated...Thanks

[JOE54]

would check pulse pump or just replace diaphragm , plugs , might check for spark also on all 6 when running bad

[xcoach]

^^^ +1

[Stubborn Hook]

I had a similar issue with my 03 XR6 that started a few years ago. The engine would stutter (misfire) when getting up on plane and when up on plane. Sometimes I would even get a momentary bog when pushing the throttle wide open to get on plane. Turned out to be the trigger. There are three coils in the trigger. Each coil signals the spark to two cylinders. After pulling my hair out trying to diagnose fuel delivery issues I had run the engine enough that two of the spark plugs finally started turning black due to all the misfiring. The two plugs were on cylinders that shared the same coil in the trigger. That was my aha! moment. So I checked each of the trigger coils with on ohm meter (easy to do), and found that the coil serving the two cylinders with the black spark plugs was reading way under the resistance range specified in the factory service manual. When I removed the old trigger (have to remove the flywheel to replace it), I saw that the epoxy sealant covering the trigger coils was cracked (perhaps from years sitting on top of the hot motor) and this might have been what ruined the coil. I suspect the triggers will last about 10 to 15 years before before cracking and needing replacement, or if you let the motor overheat it might cook them faster.

[jrh_67]

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the REQUIRED info when posting. Thanks!

I'm sorry if I missed something but I did include the serial number in the original post. The motor is a 2005 Mercury XR6-150, Serial #1B191100. If there's something else I should include please let me know.

[EuropeanAM]

That's all that's needed- my bad for missing it in the midst of your description.

Thanks!

[jrh_67]

I went ahead and ordered the rebuild kit for the fuel pump and hope to get it installed and water tested this weekend.

[jrh_67]

Well rebuilt the fuel pump. Everything went ok and the boat fired right up when I was done but when I took it out this morning it was running worse than it ever has. This problem has been getting worse and worse each trip out but today after running to a spot it didn't want to crank back up or sometimes it would crank and idle for 15 seconds or so and then die. I had to have my son pump the primer bulb and then choke it like it was a cold start and after a couple try's it would fire up and run until I stopped again although cutting out badly the whole time. I've never rebuilt a fuel pump like this before but it seemed to be a straight forward job and I really can't imagine it not being done right. One good thing to note is once it was running it idled better than it ever has but when you step on the gas it's stuttering very bad. I'm just not sure where to go from here...rebuild the carbs?

[EuropeanAM]

Are the ARROWS on all gaskets, housings and diaphragms oriented atop each other (in the pump)?

Gaskets at the MIDDLE PLATE, Diaphragms at the outside?

Mounting gasket properly installed between pump and block?

[jrh_67]

Are the ARROWS on all gaskets, housings and diaphragms oriented atop each other (in the pump)?

Gaskets at the MIDDLE PLATE, Diaphragms at the outside?

Mounting gasket properly installed between pump and block?

Yes.. It's kinda hard to get them wrong because they all have the arrows pointing out the side. The diaphragms are on the outside with the gaskets in the middle. The only thing I would question is when I took the original apart the two small circle things were only clear plastic but the new kit came with clear plastic and rubber so I put them both on with the clear plastic on the outside and the rubber touching the metal on the inside... I hope this was correct? It was a Sierra kit... Maybe I should order an original Mercury kit from you? I forgot to mention in my previous post the boat is a 2005 Triton TR-186. I bought it this past spring and it ran great until recently. One day I ran it low on gas and the next trip out this problem started. Don't know if it was coincidence or not...

[EuropeanAM]

Stop where you are at.

Go buy the CORRECT, OEM Mercury Part# 857005A1 Kit and install it.

[jrh_67]

Will do! How long is shipping usually from you to Dallas Texas?

[EuropeanAM]

Should be 3 days (or less).

[jrh_67]

OK found it local this time but since your helping me diagnose my problem ALL parts in the future will be OEM Mercury from you. I'll report back when I get it installed and lake tested. I'd like to say thank you for the advice. Good people seem to be hard to find these days....

[Stubborn Hook]

If you get the fuel delivery sorted out and still have the problem, I’d check the trigger next. Below is the one I pulled off my 03 XR6. Notice the cracks in the epoxy. That epoxy is supposed to seal the trigger coils from the environment. Once it cracks, I’m sure the coils are exposed to air/moisture and go bad. Based on the design and where it sits on top of the hot motor, I bet it’s a pretty common failing on these motors.

<Picture Removed> is from the factory manual showing the test procedure. It’s easy to test the trigger with a multimeter. When I measured mine, two coils were around 1150 ohms and one was around 450. The bad coil was the one controlling spark to cylinders 2 and 5.

The third pic <Picture Removed> shows the location of the trigger. You can access the trigger wiring harness plug near arrow C for testing. You don’t have to remove the flywheel and stator to test the trigger but you do need to if you want to replace it. I would suggest the Mercury flywheel remover tool. Good luck.

Replacing the trigger made my XR6 run good again.

[jrh_67]

If you get the fuel delivery sorted out and still have the problem, I’d check the trigger next. Below is the one I pulled off my 03 XR6. Notice the cracks in the epoxy. That epoxy is supposed to seal the trigger coils from the environment. Once it cracks, I’m sure the coils are exposed to air/moisture and go bad. Based on the design and where it sits on top of the hot motor, I bet it’s a pretty common failing on these motors.

<Picture Removed> is from the factory manual showing the test procedure. It’s easy to test the trigger with a multimeter. When I measured mine, two coils were around 1150 ohms and one was around 450. The bad coil was the one controlling spark to cylinders 2 and 5.

The third pic <Picture Removed> shows the location of the trigger. You can access the trigger wiring harness plug near arrow C for testing. You don’t have to remove the flywheel and stator to test the trigger but you do need to if you want to replace it. I would suggest the Mercury flywheel remover tool. Good luck.

Replacing the trigger made my XR6 run good again.

I guess the pictures were removed. Is there a description somewhere on how to test the trigger?

[Stubborn Hook]

I guess the pictures were removed. Is there a description somewhere on how to test the trigger?

Sorry, it was a copyright violation to post pictures of the factory service manual.

To test the trigger, you would test the resistance between the following wires from the trigger:

1. Between the brown trigger lead and yellow trigger lead.
2. Between the white trigger lead and red trigger lead.
3. Between the purple trigger lead and blue trigger lead.

Each of those three pairs of wires should have a resistance of 1100-1400 ohms.

You should be able to see the wires from the trigger coming out from under the flywheel and stator, toward the back of the motor on top. Look for the wires that look like the ones in the picture of my old trigger. Unplug the harness then you can test the resistance across those wires with a multimeter.

Note that my XR6 is a 2003, so there is a small chance the correct resistance range for your trigger might be different, but probably not. Even if the triggers have different specs, the resistances across the three coils should be similar with each other in that trigger. You want to see something like 1160, 1140, 1137. Not something like 1160, 1140, 450.

The trigger controls the timing of the spark to the cylinders. As a magnet in the flywheel passes over a coil in the trigger, the trigger sends a pulse to fire that cylinder. There are three coils in the trigger, each one triggers spark to two cylinders (each two cylinders that share a trigger coil are 180 degrees out of phase with each other). One trigger coil triggers the spark to cylinders 1 and 4. The other coil triggers spark to cylinders 2 and 5 and the third coil triggers spark to cylinders 3 and 6 as the flywheel spins around it. When you move the throttle, the trigger plate rotates, which advances the ignition timing as needed.

In my case, the coil in the trigger that triggered spark to cylinders 3 and 5 was the bad one. 3 and 5 were also the cylinders that were misfiring based on the plug appearance.




The trigger is just an easy thing to rule out and something that I think will go bad in all of them after years of service based on the design. Also, highly suggest investing in the Mercury factory service manual if you like to do your own work. Otherwise it is like flying blind. One trigger repair job and the manual has already paid for itself.

[EuropeanAM]

Also- keep two other things in mind regarding the trigger:

1. Resistance values are based on a 76 degree F ambient temperature. Warmer or colder will result in a variance.

2. When testing resistance, slowly advance and retard the throttle several times (ENGINE OFF) and watch for any sudden changes in resistance (which may indicate a wire break in the trigger harness). This occurs more often than you might think.

[jrh_67]

Tested the trigger earlier and everything was within spec. All had a reading of about 1370 but I just read your post EuropeanAM and will test it again advancing and retarding the throttle. If that test ok I'll reinstall the rebuilt fuel pump with the proper kit and give it a lake test to see what happens...

[Stubborn Hook]

That is a good point about testing the trigger in different throttle positions. The way the trigger rotates with the throttle lever moves the trigger wires back and forth, so sooner or later, they're going to wear out. You can see how the outer protective sleeve is shredded on my trigger wires in the pic. That's from all that moving back and forth with throttle movements (and being cooked on top of the motor).

Hope you get her right!