250 xs alternator ?

[dakotahunter12]

I have an 06 250 xs, my last two outings the smartcraft voltage alarm has gone off and my voltage has been dropping under 12v. I switched out batteries with an extra 31 optima I had and it worked for a day and then the same thing happened. I can watch the voltage under power varies from 12 to 13 but when I am starting out or at WOT and start trimming my volt drops and I get the alarm. I also noticed when I turn the motor over occationally all my electronics shut down. Is this just a battery issue or is it possible that I may have an alternator issue. I checked the battery connections and they where good. What battery should I be running on this motor?

[EuropeanAM]

I'd recommend checking your voltage AT the battery with the engine running.

After 5 minutes of running, you should be seeing 13.1-14.5 VDC. If you're still down in the 12-12.9V range, you MAY have an alternator problem.

In that case, check the voltage at the LARGE RED output wire ON THE ALTERNATOR (with the engine running at idle). Report back with your results for further assistance.

As for batteries:

http://www.bbcboards.net/zerot...st-in

[dakotahunter12]

brought my boat to the dealer had them do a quick check and they say the alternator was producing a charge when they ran it. The kid I talked to (not the tec) said it was 12.8 on their meter but isn't that low for an xs?

[lpugh]

I going to add to what Don said, set you DVOM for AC volts and check the voltage again at about 1500 RPM. There should be no more than .5 volts AC. This test will find Diodes and stators that have failed. You can have 14.4 volts dc and still have a bad diode that will cause a 30% reduction in amperage available, another words a 60 amp alternator becomes a 40! Guess what, you lose 2 diode or two stator sections and now it is a 20 amp unit. It can still maintain over 13.5 volts.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by dakotahunter12 &raquo;</td></tr><tr><td class="quote">brought my boat to the dealer had them do a quick check and they say the alternator was producing a charge when they ran it. The kid I talked to (not the tec) said it was 12.8 on their meter but isn't that low for an xs? </td></tr></table>

That's definitely low.

I'd suggest running the two tests described above.

Report back with your results.... the test I gave (for the large red output terminal) should be done with your meter set to DC VOLTS.

The test Leon gave required an AC VOLTS setting.

[dakotahunter12]

Well I ran the two test you suggested and the result where as follows
after a five minute idle a test at the battery terminals gave me a voltage reading of 12.8

at the alternator I was getting 12.7

I tried the ac setting but did not get a reading, I had my tester set to VAC 200 and the reading was 0.00 but I did not bring the rpms up to 1500, I neglacted to remember that part of the test and only did it at idle.

I am bringing the boat back to dealer tomorrow, what should I have them look for?

A side note I did use the boat this weekend and at one time my voltage was reading 13.5 at 3/4 throttle but most of the time I was still at the 12 to 12.8 range.

[EuropeanAM]

DISCONNECT BATTERY before proceeding:

Check the tightness of the output lug on the alternator. This is the large red terminal. If it is loose, it can adversely affect alternator output.

Also, double check the wiring up near the oil pump (below starter). There should be a red, bullet-connector wire there (with several other loose wires). This red bullet connected wire MUST be connected for the alternator to function.

Check the battery cable connections AT THE ENGINE. Don't forget to check the NEGATIVE cable (attaches to block with a bolt below the starter). Make sure that you CANNOT rotate the cable on the attaching bolt (have seen a few where too much loctite past was used- bolt was tight in threads, but cable lug would spin under head of bolt).

Finally, load test the battery.

If you don't find it- have the dealer proceed with alternator testing as necessary.

[dakotahunter12]

i just picked my boat up from the shop and I talked with the Tec as to what he found. He removed the alternator and had it tested and it was in working order so he traced all electrical connections cleaning and reinstalling them through the whole system, he figured he would find a faulty wire or relay but he did not. After going through all that he said he got the charge back up to where it should be. I had him replace all the plugs and the fuel filter. He also found a pin hole size leak in one of the return oil lines and was able to fix that as well. I had him check my throttle position sensor and that checked out good. He figured my low voltage could of been the reason my motor had a hesitation when I dropped the hammer from a dead stop. I will be on the water this weekend and hope I have everything in working order. one question though, is the fuel filter the only filter on this motor that needs replacing?

[EuropeanAM]

Yes, the fuel filter would be the only filter replaced when servicing the 250 XS. No air filter involved.

You might want to take a test meter and verify your VOLTAGE at the battery, before starting, after starting, and after running.

You should see at least a .5VDC increase in voltage after starting the engine, and the running voltage will usually be in the 13.1-14.5VDC range.

You may also want to have your battery LOAD TESTED to confirm it's capacity, and health. See this post for more information on batteries:

http://www.bbcboards.net/zerot...st-in

[dakotahunter12]

ok I am still having the same issues. I didn't have a tester with me but before I start the motor my voltage is anywhere from 11.7 to 12.1 on my smart gauge and both graphs. I start the motor and let it idle for a few minutes and the voltage goes up to 12.2 to 12.6 if I drop the throttle hard it drops back to 11.8 to 12.2 for a few seconds and if I try to trim up it drops drastically, a few occasions it went as low as 11.2 and the voltage alarm sounded off. If I went on a long run 5 miles or so I seen voltage between 12.8 to 13.3 at the highest but if I touch the trim or jackplate switch it drops so I found myself gradually trimming allowing the voltage to bounce back and then trimming again til I got it to the sweet spot. I called the shop when I was out on the water and talked to the tec, he suggested we just have the alternator rebuild, he said the battery which I purchased from them this spring was good on there meters and he said they did load test it twice. Should I just drop the $100 bucks and have the alternator rebuilt? I already spent $200 having them go though the whole system wire by wire, I just want to get all the kinks out of this Merc so I can concentrate on fishing.

One more question for you Don and by the way I really appreciate what you do here it is a great help. My trim settles on the 250xs, it is an internal leak and very annoying. If I trim up the motor It will settle all the way down with in a few hours (out of the water)and I have noticed that on the water I have to hit the trim button every 10 seconds or so to keep that sweet spot. The shop told me that after talking to mercury they said it could be one of two things a bad interior o ring which runs $75 and would take 4 shop hours to replace at $120 an hour so it would be around $550 or so but it could also be a scored cylinder and if that was the cause I would have to replace the trim assembly at $1200 but if I gambled on the o ring and it was the cylinder I would be out the $550 plus I would have to spend the $1200 for the new trim assembly. I like the performance of this XS but I am starting to miss the reliability of my old 02' yamaha HPDI

[JAZII]

From your last post.

I THINK YOU NEED A BETTER BATTERY.

Just remember, your motor alone needs 1000 MCA, factor in the graphs and everything else on the cranker.

One thing to check on the trim unit.

UN SCREW THE MANUAL RELIEF ALL THE WAY OUT, till it bottoms out lightly, then tighten it firmly.
Sometimes the O-rings on the relief screw leak by.

JAZII

[dakotahunter12]

Jaz
? if the releif valve where leaking wouldn't I see some fluid on the assembly or the floor in my shop?

[JAZII]

No, it's an internal bypass valve.
JAZII

[EuropeanAM]

I think we need to go back to SQUARE ONE:

-Please specify WHAT BATTERY you are running- brand, model, CCA spec and MCA spec.

-Get your hands on a digital volt meter, and go back to the beginning of this post, performing each test listed. Report back with results. Don't forget the one early on for voltage on the LARGE RED OUTPUT LEAD of the alternator (with and without engine running, please).

---------------------------------------
On the trim leakdown, this is commonly caused by one of the following:

-Loose or improperly seated Manual Release Valve (internal leak)
-Damaged O-Rings on the Manual Release Valve
-Damaged check valve in the PORT SIDE trim ram
-Damaged or debris filled pump check valves
-Internal o-ring leaks within the trim system (dozens possible).

You might be able to address the first two or three items above on your own.... the later ones require complete system teardown.

[dakotahunter12]

I already took off the alternator so I took it in myself to have it tested. I took it to the same shop that the boat shop took it to and they said yep it's good but when I asked the amp output they said 20, I questioned why so low since it's a 50 amp alternator and they said no it's good. It didn't seem right so I took it to another shop that has done some work for me and he tested it, he even had the wiring harness to match the alternator and it only produced 28amps and they told me that something wasn't right with it. They asked me to verify what the output should be so I called customer service for Merc, gave them my serial number and they said it should produce 48 to 50 amps at 2000 rpms and 14.4 volts, which it is not so I guess a new alternator is in order.

Battery ?, I currently have an Interstate Marine cranking battery with the following specs, 24m-xhd 800cca 1000 mca. Is this battery OK or should I swap out for a Optima 31 series?

Trim ?, I can not locate the manual relief valve for the trim, Does anyone have a picture of its location? or at least a description of where its located, I see nothing that looks like the relief valves I have had on past motors.

[EuropeanAM]

Sounds as though you've determined the alternator is faulty. If a replacement does not solve your problem, go back to the voltage tests way early on in the post.

The battery you have described will (provided it is actually in NEW condition, and fully charged) meet the ABSOLUTE BARE MINIMUM SPECIFICATION for your engine. This means you can run NOTHING in your boat- no pumps, no graphs, etc (or your battery will be short on capacity).

My suggestion: Pick a new battery from the list in the following post:

http://www.bbcboards.net/zerot...st-in

To locate the manual trim release screw:

Stand on the RIGHT or STARBOARD side of the engine. Locate the Starboard Transom Bracket (this is the bracket that bolts the engine to the transom or jackplate). There is a hole in the side of this bracket- down inside the hole should be a plastic screw with a large FLAT HEAD. Keep in mind- it should only be opened a maximum of 1.5 turns.... and be VERY CAREFUL when you snug it down not to OVERTIGHTEN (it will break).

[dakotahunter12]

I am waiting on the alternator so I guess I will let that issue rest for the moment.

I did purchase a new Ultima marine 31 series battery and have put that in the boat

I figured out why I can't find the manual relief, I must have a different trim system than most, my ram has fluid lines that run into the back compartment of my ranger and the electric motor and valve assembly are located in there. I stopped and asked the tec at the marine shop I use and he said there isn't a relief valve on this system? That seems strange. According to them there is no parts on mercury's system for the valve assembly so if it is that I would need a new one. If it is a an O ring in the ram that could possibly be fixed by one of the local hydraulic companies. Don does that sound right?

[EuropeanAM]

Yes, that sounds right. Your engine is apparently equipped with the Heavy Duty (offshore) Trim System.

[dakotahunter12]

WE HAVE VOLTAGE!!!!!!! I put the new alternator in this morning fired up the motor and I am getting 14.4 volts at 2000 rpm, right on specs. Thanks Don for all the help. I will tackle the trim settling use after I go fishing this weekend.