1987 Mercury 150- Stator??

[hkeiner]

Re: 1987 Mercury 150- Stator??

What is causing this (darn!) water temp issue

If you determine that the the motor is really overheating, the below links my help troubleshoot the problem. One link shows how to install a water pressure gauge to monitor the changes in the cooling system's PSI at various RPMs. Another link contains a troubleshoot guide listing the possible causes/fixes. Even if you find that the PSI readings are normal at all RPMs, having a water pressure gauge on the boat is a great way to monitor the health of the cooling system on an onging basis. Much better in my opinion that just watching the tell-tale from time to time.

Just my thoughts...


http://forums.iboats.com/attachment.php?attachmentid=26808&d=1240517707

http://forums.iboats.com/attachment.php?attachmentid=26806&d=1240515681

http://www.diy-boat.com/index.php?option=com_content&task=view&id=151&Itemid=49

 

[sschefer]

Re: 1987 Mercury 150- Stator??

Again, not being totally familiar with your engine but having seen the parts manual now, the second temp sensor is for the second bank. Your sensors work like idiot lights. If either one goes over limit, the alarm module will sound the alarm. If your module is like mine that's all it does is sound an alarm.

So, if any of that holds true for your engine then the low rpm condition is most likely being caused by a faulty ignition system and my suspicion would be the stator. That's just my two cents using my own convoluted logic so borrow your buddies DVA and test the output.

As a side note, I think most will agree that if you change the stator you should also change the trigger. Just like if you change your switchboxes, change your coils also.

My theory on why your temp gauge pegs is because someone wired the alarm module to it. I can think of a couple of possibitlities as to how that might be done but nothing that I'd want to tell you to go looking for. It would be best if you used your manuals wiring diagram to find the correct wiring for the module and see if yours complies.

 

[j_martin]

Re: 1987 Mercury 150- Stator??

Hey John:

Thanks for keeping watch on this thread - I can't tell you how much help all of you are!

And, I know I admitted to ignorance earlier; I was wrong - I'm just stupid! Once I removed the port side water jacket it was instantly apparent that no piston has ever crunched my water temp sensor!

BTW John, no blockage in the cooling jacket, so I guess i'm back to square one.

I also cranked the motor and let it idle to temp; removed the port sending wire and the gauge went dead. Not that sensor anyway!

Why is there another sensor on the starboard side leading to a rubber-insulated post and then on to the oil injector warning module? That makes no sense to me but, remember, I am stupid!

(I can prepare, cook and serve a five-course meal to 300 guests in my sleep! Why can I not get one outboard motor to work?) UGGHH!

While hunting the replacement sensors and water jacket gaskets I learned (ahem, was told!) that this motor features a "limp mode" that is triggered by excessive temp to prevent major damage from overheating. Is this true and, if so, is it the starboard water temp sensor (mentioned above) that initiates the signal for "limp mode"?

I did quite alot of research on the mechanic that I used for the carb and fuel pump rebuild - his credentials are tremendous and ALL of the references gave him accolades (he supplied some references and I personally knew the others). He has been suggesting stator since day one but, as CharlieB pointed out in an earlier post, that's a pricey one. So are the trigger assy, switches, coils/wires, etc (I'm looking at about $1K to just replace all of them - and still no "warm and fuzzy" feeling that any of it will correct my issue.

When I acquired the boat several months ago, the first thing I did was drain and clean the fuel tank, installed new pickup and anti-siphon barb, replaced ALL fuel lines with ethanol-rated ones, installed a new fuel/water separator, new primer bumb (and line) and new connector at the motor. I just had the carbs and fuel pump rebuilt and a (newly) rebuilt lower unit. I'm running the same prop that came on the motor. The fuel is fresh and contains NO ETHANOL.

I just don't understand how this can be fuel related. Carb issue, maybe, but until I can get some rpms under load, how will I know? Doesn't the finetuning process need to be done under an actual load?

What is causing this (darn!) water temp issue

The sensor on the starboard side is the temp alarm switch. It shares the alarm circuit with the oil alert module. Replace that switch.

The sensor on the port side is the temp gauge sender. It is a totally different circuit.

That thing doesn't have any "limp home" circuitry or signalling. It is limping because it is hurting.

I strongly suspect that whoever "rebuilt" the carbs messed something up, or maybe didn't clean out the fuel distribution lines and the carbs are fuddled up again.

If you don't have a mercury factory manual for that engine, get one, and read it.

I just noticed you installed an anti-siphon barb. If there is no fuel equipment below the tank top, you do not need that anti-siphon valve. They're noted for troubling this engine type.

If you were to bring it to me for service, I would.
1. do a compression check. Verify basic engine health.
2. Check wiring routing to make sure something didn't get crossed, especially on the ignition. (who knows what whats his name did to it.) Also check bleed line routing.
3. Test stator output at cranking with a DVA at the switchboxes. Replace stator if needed.
4. Do a spark test at cranking. Looking for strong spark on all 6. Checking switchboxes and coils.
5. Do a link n sync on it to verify proper timing and linkage operation.
6. Finally, put fuel to it. Set up and verify at idle. Checking carb idle circuits, reeds, and bleed line check valves.
7. Install fuel pressure gauge and lake test. Notice if fuel pressure fails when the engine balks. If it does, service the fuel delivery system. If it does not, service the carbs.

Should be running right now.

Set idle on the lake. Do a WOT power cutoff and check the plugs for even and proper burn. (final test of main jet mix)

You need compression, fuel, and spark to run. systematically verifying each in sequence is the way to bring up a troubled motor.

This engine is a box of dynamite with a leash on it. Mistiming, or lean fuel mixture can burn down major hardware in seconds. When set up right, it is strong and reliable. Keep guessing, and you'll burn it down in due time.

hope it helps
over and out
John

 

[Maddogop4]

Re: 1987 Mercury 150 - Stator??

Re: 1987 Mercury 150 - Stator??

What are the common starting problems for this engine? I had it started last year then my Dad burned up the starter. It's been replaced but no start. Turns over fine and gas is flowing but no fire. I know about checking the plugs while grounding on the block. Any other good checks?

Thanks,

Mark

 

[hkeiner]

Re: 1987 Mercury 150- Stator??

First, it is better to start your own thread rather than add on to another person's thread. Having said this, I suggest that you use a spark tester to determine if there is a good spark on each plug wire and report back on what you find. Grounding plugs to the block to check for spark will show a completely missing spark but not so good for testing for a sufficiently strong spark.

 

[coastalrichard]

Re: 1987 Mercury 150- Stator?? UPDATED!

Re: 1987 Mercury 150- Stator?? UPDATED!

Hi again everyone!

Well, I've replaced the stator and rectifier. Tach now works fine and the voltage at the battery is 12.39-12.40 @ idle and increases to 12.63-12.65 @ 2000 RPM. Won't put in the water today - too busy catering!

John - Today, for the first time, I notice a very small amount of water exiting the poppit valve right after the motor is cranked. It stopped pretty quickly. Upon inspection, I also noticed a droplet of water at the base of the starboard cylinder bank. I note that the head gasket on the port side looks fine (it's blackish) while the gasket on the starboard side looks more degraded (kind of rusty looking in places). In your previous post (June 16) you mentioned some cooling issues. Could you respond to my observations?

 

[j_martin]

Re: 1987 Mercury 150- Stator??

The poppit should not leak out the vent hole. Diaphragm is bad.

Head gaskets shouldn't leak.

Did you test/replace the overheat sending unit - the one that wires in with the oil alert module?

Have you acquired a Mercury manual for that motor?

John

 

[coastalrichard]

Re: 1987 Mercury 150- Stator??...RESOLVED!!

Re: 1987 Mercury 150- Stator??...RESOLVED!!

Many thanks to all who took time to offer their expertise! There's a seafood extravaganza with your name on it when you visit St. George Island, FL (and I KNOW how to fix that!).

Here's the recap:

The RPM issue was, in fact, a bad stator (high side windings). Replaced! (thanks CharlieB!)

The spiking temp gauge was no more than the (port) temp sender which had been overtightened causing it to "bottom out" against the head cover. The OEM replacement part (exactly like the one I removed which was "crumpled" due to overtightening against the head) was too long so I shimmed it to prevent the metal to metal contact. (thanks sschefer!)

Double-checked poppit valve - it did have a tear at it's edge under the outer gasket that I missed the first time. (thanks John!)

1987 Black Max 150 now purrs like a kitten and runs like a lion!

 

[j_martin]

Re: 1987 Mercury 150- Stator??...RESOLVED!!

Re: 1987 Mercury 150- Stator??...RESOLVED!!

Many thanks to all who took time to offer their expertise! There's a seafood extravaganza with your name on it when you visit St. George Island, FL (and I KNOW how to fix that!).

Here's the recap:

The RPM issue was, in fact, a bad stator (high side windings). Replaced! (thanks CharlieB!)

The spiking temp gauge was no more than the (port) temp sender which had been overtightened causing it to "bottom out" against the head cover. The OEM replacement part (exactly like the one I removed which was "crumpled" due to overtightening against the head) was too long so I shimmed it to prevent the metal to metal contact. (thanks sschefer!)

Double-checked poppit valve - it did have a tear at it's edge under the outer gasket that I missed the first time. (thanks John!)

1987 Black Max 150 now purrs like a kitten and runs like a lion!

As it should. If you pay close attention to details, and notice anything not quite right, you can maybe avoid a confusing avalanche of problems like this one.

Don't know if I'll ever again get back to Florida, but I'll take you up on it if I do. Last time there was with the Navy in 1966. Still remember snorkel diving for longoosters ( Caribbean Spiny Lobster) at Key West.

John