2 stroke randomly does not want to start + house battery voltage seems low

[Magnumpl]

Hi. I have a 2005 Mercury Saltwater XL SW 150hp 2-stroke carbureted outboard. I previously had an issue with starting the motor due to fuel not being primed, I had to prime the bulb for 10 minutes in order to get the fuel in the filter. I replaced all fuel lines, bulb, valves, changed all wiring and remote control. Also replaced the 3-way switch with an ACR and dual circuit plus switch. The batteries are new as well, I have a 27 starting battery and 29 deep cycle battery.
Now the bulb primes within only 2-3 squeezes. The motor starts usually starts right away. However there are times when it will crank but will not start. I have not replaced the key starter. The fuel pump was rebuilt a year ago but I purchased the diaphragms to see if it helps.

- What could be the issue?

My starting routine is as follow
Cold:
Prime the bulb - push the throttle only button -> engage the throttle a little bit forward -> key to on -> press key to choke for 5-6 seconds -> start the engine -> shift controller back to neutral
Warm:
Just turn the key to start, if not willing to start, I treat it as it was cold.
If it still won't start with a few tries, I engage the gear (controller forward without pressing the throttle only button) and it will always start, with more smoke.
What's odd is that it even starts on gear, since it should have a safety switch, or it's not wired right. 2 yellow/red wires are coming out of the Mercury Binnacle gen2 remote control, one is wired to the ourboard harness and other one is wired to the key switch harness.

- Does that seem normal?

Another issue, which shouldn't be related since I have the ACR, but the house battery voltage is 12.1 - 12.2 most of the time, sometimes dropping to 11.9. Both, the voltage meter and MFD showing same voltage. It shows this voltage no matter is the engine is running in gear or idling, or not running at all.

- Shouldn't it be higher, or at least increasing when it is running? I've never seen it dropping below 12v with engine running before.

Just to add, I checked the amperes on the engines positive wire with a clamp meter and it showed around 5A while idling dry. According to the manual, the charging amperage for this engine is 40A at 5000RPM.

- Is that a normal amperage?

One thing that I've noticed, is that the spark plug shocks when touched with engine running. My friend tried to find the issue and touched it by mistake. The engine seemed to be hissing somewhere underneath the carbs (?) when it started, I'm not sure if it was doing that before. He even pulled the plug out while the engine was idling, but nothing happened.

- Shouldn't the motor stop when plug is pulled out? Is that normal for it to shock then touched from the exterior?

I would really appreciate your help and suggestions on what to change or check. Not sure if any of these are related and normal for this type of engine.

 

[racerone]

Key must be pushed in and held in while cranking the motor for starting.

 

[Magnumpl]

Key must be pushed in and held in while cranking the motor for starting.

Oh okay! Thank you!
That's something I haven't normally done, unless I got anxious after multiple tries and pushed the key while cranking, not sure if the motor started that way or not but I'm sure I've done it in nerves sometimes
That's a valuable point, I will definitely keep that in my head on my next trip.

 

[Magnumpl]

I will get the compression tested as well.

The engine is also making a grinding sound when shifting into gears. It was like that since I got the boat. I am not sure if it's normal or not.
It's sounds exacly the same as in this video:

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[racerone]

shifting MUST be done with a quick firm motion.------No " granny shifting " is to be done.

 

[Magnumpl]

shifting MUST be done with a quick firm motion.------No " granny shifting " is to be done.

Even with quick shift, it still grinds.
To add, it's pretty difficult to switch gears or going out of gear quickly becase the lever is a "fly-by" with no firm stop in neutral so it's very easy to skip neutral or switch from gear to gear accidentally.

 

[Magnumpl]

The starter battery showed 13.1v with a multimeter and 12.6v on a charger (not sure why it was different). The house battery showed 12.1v on both so it is currently being charged. For some reason it was not being charged with the alternator, it showed the same voltage before, during and after my last trip. The starting battery is topped so this one must have indeed been charged. Should the BlueSea SI-ACR charge the starting battery first and then switch to house battery?

Also, does 5A on engines positive wire while idling sound right?

I also checked the compression and its 115 on 5 cylinders, one cylinder is showing around 105. I checked it on cold engine. With throttle engaged its around 3-4 psi higher.
I will decarb it with seafoam since I never done this. Is that a good idea?

How about the grinding sound when shifting gear? Is that normal?
I checked the remote control lever by shifting into gears while spinning the propeller, with engine off, and it grinds while shifting into forward as well

 

[dingbat]

The house battery showed 12.1v on both so it is currently being charged. For some reason it was not being charged with the alternator, it showed the same voltage before, during and after my last trip. The starting battery is topped so this one must have indeed been charged.

The Blues Seas has both a charge and isolation functions.
It will not open the charge relay until it see 13.2 volts and it will not connect to a battery that has less than 12.4 volts.

Your house battery (12.1V) isn't charging because the voltage is too low.

Also, does 5A on engines positive wire while idling sound right?

There is a voltage and amperage component to electricity........i.e. 13.5 volts @28 amp = 378W

Can't assess the performance of your charging system without a voltage reading

If you charging system is working right you should ~13.5 v on the battery with the motor running

 

[Chris1956]

Mercs usually have preload on the throttle cable to help you find neutral. To do that, adjust the throttle cable at the engine, in neutral, to push the throttle closed a bit more to add the preload.

 

[Magnumpl]

Mercs usually have preload on the throttle cable to help you find neutral. To do that, adjust the throttle cable at the engine, in neutral, to push the throttle closed a bit more to add the preload.

Could you help me understand the preload? I tried to look it up but can't find to much information. The manual does say something about the preload too.


I topped both batteries and the voltage is 12.8v on both with engine off. I still had a hard time starting the engine. Took 8-10 tries.

Just my thought. I looked at the manual and the fuel line connectors are a tiny bit different.

The manual shows a 5/16" hose -> check valve -> 5/16" hose -> into Tee connector .
Not sure how they want it before that first tube.



I don't have any of these cirled in red. I have it like this starting from the fuel tank.
Fuel tank -> Anti siphon-> 3/8" hose -> (temporary eliminated water separator to see if it helps) -> Primer bulb -> 3/8" hose -> Tee connector



I don't have the check valve, however the primer bulb should have a built in check valve, right? Should I add another check valve before the tee?
i also have a 3/8" hose connected directly into the tee. Should I use a barbed reducer in between the bulb and the tee?

Could this also cause the starting issues?
The bulb is always hard and the filter is filled with fuel without any issues.

 

[havoc_squad]

Could you help me understand the preload? I tried to look it up but can't find to much information. The manual does say something about the preload too.
View attachment 390119

I topped both batteries and the voltage is 12.8v on both with engine off. I still had a hard time starting the engine. Took 8-10 tries.

Just my thought. I looked at the manual and the fuel line connectors are a tiny bit different.

The manual shows a 5/16" hose -> check valve -> 5/16" hose -> into Tee connector .
Not sure how they want it before that first tube.

View attachment 390120

I don't have any of these cirled in red. I have it like this starting from the fuel tank.
Fuel tank -> Anti siphon-> 3/8" hose -> (temporary eliminated water separator to see if it helps) -> Primer bulb -> 3/8" hose -> Tee connector

View attachment 390121

I don't have the check valve, however the primer bulb should have a built in check valve, right? Should I add another check valve before the tee?
i also have a 3/8" hose connected directly into the tee. Should I use a barbed reducer in between the bulb and the tee?

Could this also cause the starting issues?
The bulb is always hard and the filter is filled with fuel without any issues.

Preload on throttle cable is straightforward.

The objective is to remove any slack/movement of the throttle cable attached to throttle arm of outboard when control box is in neutral with no throttle only/min throttle.

Throttle arm has to be against the stop. If you change the stop you have to re-adjust the cable preload correctly.

Slack will cause minimum set engine idle speed to be inconsistent and is hard on lower unit gearcase.

If you run out of throttle cable nut adjustment to take up the slack to achieve needed idle RPM in service manual, the cable is bad, or engine is not synced properly, or you have serious engine performance issues.