90TLRV Crank Position Sensor Install?

[Jake1821]

Short question and then some background:
I removed the CPS from my 1997 90TLRV (2 stroke, 3 cylinder) in order to test it. The engine was rotated with the CPS off and now I wonder whether I need to align the engine before I reinstall the CPS. I’m concerned about getting the timing/firing correct with respect to the position CPS relative to the Rotor Assembly. Does anyone know if there are any alignment/index marks which correspond to the installation of the CPS? I’ve searched in the Service Manual (LIT 18616-01-69) but can’t find anything that references this. Any help will be greatly appreciated!

Background:
The problem I was having is that when I first start the engine, there is no spark on cylinder #2, and it doesn’t rev past 2200 rpm under this condition. After about 15 minutes and when the engine is warmed up, spark on #2 comes back and the engine runs fine all day. The problem started about 5-6 weeks ago as the air and water temps have gotten cooler. I’ve read a couple of posts on this forum which suggest that the CPS could be the cause of this problem. I’ve cleaned the corrosion off the CPS and it seems that the magnet now has a stronger pull to it. There are no cracks or any other visible concerns with the CPS. I plan to reinstall it, run the engine and if the problem persists I’ll continue with the diagnostics as per the Service Manual to determine if the CPS is still the problem or perhaps the CDI. Ignition coils and spark plugs are in good condition. Other than this issue, the engine runs strong and there are no compression or fuel related problems. Just hoping to reinstall the CPS without creating another problem.
Thank you

[Jake1821]

I think I answered my own question on this.

I looked at the Manual again and believe I found the solution. Referring to the section “Ignition Timing Adjustment”, if I simply align the flywheel with the TDC1 mark while cylinder #1 is at TDC, I’ll know the timing is right and then I can simply install the CPS in its location and the timing will be correct. I guess I was thinking there would be a timing mark on the flywheel that corresponds to the CPS but clearly this is not necessary since timing is set by the existing TDC1 mark which corresponds to cylinder #1.

Probably an unnecessary post, but it actually helped me think through then problem. Hopefully it can help anyone else who has this question.

Now, back to diagnosing the CPS and no spark issue. I will post back once that is resolved.

[bkurth922]

For a minute I thought you ended up with my old engine but it was a 99. Absolutely exact same issue, there is a thread here somewhere. Thought replacing cps fixed it but I think it was just warm enough that day to make the problem go away. Mine was 100% a bad CDI issue. The guy who bought my skiff replaced it and the problem went away immediately.

[bkurth922]

I’m not sure on the resetting of the flywheel and cps by the way, to answer the original ?

[Jake1821]

Short update on the issue:
I cleaned and lightly sanded the exposed magnetic metal surface on the CPS, which is the part of the CPS that is closest to the teeth on the flywheel. I re-installed it in position and put the boat in the water. Started the engine and same issue – no spark on #2. Once again, after about 15-20 minutes #2 starts to fire intermittently and shortly thereafter the engine runs smooth and strong for the remainder of the day. Although each ignition coil previously tested good for resistance, I decided to swap coils #1 and #2 and started the engine the next day. Same thing, no spark on #2.

I’ve removed the CDI and will inspect it for cracks or visible damage. Will also re-inspect all wires and connections. For now, it seems that ignition coils, spark plugs and the coils firing #1 and #3 are fine so it’s looking like the CDI may be the problem. Before concluding on the CDI, I will try swapping the current CPS with a known good CPS and if that doesn’t fix the problem it seems that the last resort may be a faulty CDI.

bkurth922 – sounds like this was your exact issue. Based on reading a few other posts and having watched a few videos, it seems that the Yamaha CDI failures for these engines are not all that uncommon.

Will update this post with final results but that will likely not be for a few weeks.

[Keithbaja]

Let's start with the CKP...... NOT cps....Grrrr

[Jake1821]

"Let's start with the CKP...... NOT cps....Grrrr"

CKP?

[Keithbaja]

I work on engines for 45+ YRs. Fuel injection and Electrical Spe******t. CKP is the proper acronym for a crank angle is sensor.. A check engine is really a MIL..

[Keithbaja]

I work on engines for 45+ YRs. Fuel injection and Electrical Spe******t. CKP is the proper acronym for a crank angle is sensor.. A check light engine is really a MIL..

[99yam40]

"Let's start with the CKP...... NOT cps....Grrrr"

CKP?

he tends to come up with strange things, so pay no attention.
you can tell from his writing
I have no idea who his MIL really is or if he even has one

[Jake1821]

Well, alright then, I stand corrected – CKP from now on.

Incidentally, when you search this forum for “CKP”, you will find 2 posts (other than this topic). However, if you search for “CPS”, you’ll find over 200 posts. I guess Keith has a lot of posting to catch up on

[Keithbaja]

WELL, search all you want. As a top Tech making 95 hr if you want to argue with me. Go for it. A crank angle sensor is referred to in the biz as a CKP... FACT !! It puts out ,02 to max 2 volts AC. Most have around 2K ohms of resistance. And a air gap of 30 to 50K... Get a GRIP !!

[TownsendsFJR1300]

You have to search Mercury CKP to find it,.:


https://www.amazon.com/Crank-Positio.../dp/B08GF7QRDR





Capture.JPG

[99yam40]

I work on engines for 45+ YRs. Fuel injection and Electrical Spe******t. CKP is the proper acronym for a crank angle is sensor.. A check light engine is really a MIL..

I just do not see how CKS would be an abbreviation of a Crank Angle is Sensor like he wrote.
Or even a MIL being an abbreviation of a Check Light Engine

[TownsendsFJR1300]

I just do not see how CKS would be an abbreviation of a Crank Angle is Sensor like he wrote.
Or even a MIL being an abbreviation of a Check Light Engine

It seems it's a MERCURY only abbreviation as I couldn't find it listed elsewhere.

I've never seen it in my Yamaha factory shop manual..


I've never looked in a Mercury manual, I don't care for working on them..