Stator or more on mercury xr4, please help!

[ammons17]

So I have a '89 Black Max xr4. When I first got my boat the motor ran good but has gradually gotten worse. At first I thought it was a bad fuel line so I've changed that, changed all filters several times thinking it was ethanol build up, and now have just recently cleaned the carbs. So now here's there weird part. I fish a lot so i could tell when it was getting worse. It started with a hesitation in take off, the got worse and now, when you try to go anything faster than just idling in gear in stalls. I've heard stator but I'm not for sure, any help would greatly be appreciated.

 

[Chris1956]

Re: Stator or more on mercury xr4, please help!

Well, A compression test and a spark test is in order. It could also be dirty or misadjusted carbs. Did the stalling upon acceleration start right after you cleaned the carbs?

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

No I actually havnt ran it since the carb cleaning, but the reason I think its not that is the carbs we practically clean, I mean so tarnish but that's it. And I have spark on all cylinders so I'm stumped.

 

[CharlieB]

Re: Stator or more on mercury xr4, please help!

Timing is everything to these motors. Anytime the carbs are removed they should be 'Linked and Sync'd' to ensure the ignition timing is advancing correctly with the throttle opening.

Never assume anything, especially ignition and carbs. PROVE everything.

First, reclean the carbs, pay particular attention to the idle passages and air bleeds. These are very small passages and even a small accumulation of mineral will reduce flow and cause off-idle stumbles.

Do you have a factory service manual? It is critical to adjusting carbs linkage and timing. Follow the steps exactly as written, as many are dependent on one another for crisp performance.

Lastly, if you suspect an ignition problem, download and study the CDI IGntion Guide, available free here.

ISSUU - CDI Electronics Practical Outboard Ignition Troubleshooting by CDI Electronics

This guide spells out step by step testing of each ignition component. You will need either a DVA meter or a DVA adaptor to use with any volt/ohm meter.

Welcome to iBoats.

Repost your progress and any other questions you need help with.

 

[CharlieB]

Re: Stator or more on mercury xr4, please help!

Have you checked the fuel pump output? If it is not a strong pulsed stream it needs a rebuild kit and/or new fuel hoses and primer bulb.

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

I have changed the bubble and all the fuel line, and the guy that cleaned them really knows what he's doing. He's cleaned hundreds and I thought of the fuel pump and changing the impeller and all that because I don't think we did when I first got it.

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

Just thinking of what you said, doesn't the fuel pump make more sense of gradually getting worse, I mean electrical seems like it would just go bad instantly. And that explains the firing of all cylinders.

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

Also I read it might be a diaphragm in the fuel pump and the fuel pump just can't keep up and it floods it. If it was this would there be a little in the water because I remember seeing a little shiney stuff in the water you know when oil or gas goes into the water it shines

 

[CharlieB]

Re: Stator or more on mercury xr4, please help!

RPM is dependent on fuel flow. As the fuel pump output is reduced so is WOT RPM.

If the fuel pump diaphragm is old and stiff, it cannot flex and make a full stoke and output will be reduced. The motor will not flood unless there is a pinhole in the diaphragm allowing fuel to leak directly into the motor crankcase.

Check fuel pump output to the carbs, it should be a very strong pulsed stream while cranking. Replace that hose between the pump and carbs with a clear hose, start the motor and watch that clear hose to see if air bubbles keep passing thru, indicating air sucking into the hoses anywhere between the fuel pump and tank. This too will limiit fuel flow to the carbs and reduce WOT RPM.

Always remember to remove that clear hose once finished as it is NOT rated nor recommended for fuel. Only for very short term testing tool.

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

So do you believe it is stator or problems with the fuel pump

 

[carholme]

Re: Stator or more on mercury xr4, please help!

If you haven't tested the fuel flow output from the pump when cranking and the boat is still in the water, run the engine, put it in gear and add throttle. With someone at the fuel primer bulb, have them start pumping the bulb as soon as throttle is added and see if the engine acts normally and moves the boat. If it does, you will have a good idea that the fuel pump needs to be rebuilt. If it acts the same, you have problems elsewhere.


Gerry

 

[ammons17]

Re: Stator or more on mercury xr4, please help!

I found out today guys. Wasn't a fuel problem, although it didn't hurt changing the fuel pump diaphragms. It was bad head gaskets. Not too bad, it beats electrical so I'm happy. Thanks for all of everyone's support.