200HP 2.5L Mercury Dies at WOT will not restart. Please help.

[mbtskysurfer]

Guys (and Gals),

It is not often that I find myself with absolutely no clue what to do. Yet I find myself there with the Mercury on my Cape Horn.

Let me tell you what is happening and I will leave it to your very capable knowledge to help me get this thing running again.

This summer she gave me a problem not running over 2000rpm even at WOT. After much frustration and a lot of cussing I started to replace parts. As I am sure everybody with an outboard does in the beginning. I have replaced the spark plugs, fuel lines from the tank to the bulb and the bulb to the Tank/Oil Pump/Fuel Pump Tee. (Yes I took out the quick connect on the engine). This did not help at all. Next we tried the spark advance, put new switch packs. This helped. I got the boat to run at 5000 - 5500 with no problems for about 5 minutes. Then she would slip back to 2000 rpm and do nothing. I took her home and drained the whole gas tank by hand (150gal) what came out vaguely resembled gas. I replaced the fuel filter, filled it back up, and put StarBrite in the tank.

It was great! She would do what ever I wanted. Took her out on three full day trips. I had finally licked my problems. I was a happy boat owner.

However.... (it seems there is always a however)
Two weeks ago I put the boat in the water to go check my crab traps, like I had done three days before. She started normally. I got out past the "No Wake" area and took her up to WOT. She climbed as normal up to 4500 - 5000rpm and died. I don't mean died back to 2000rpm. I mean she died completely. She would not start at all. I had to be towed in. I took her back to the house and the next day I began working on it. After almost 30 minutes of turning it over. I finally got her to start, I did this by holding down the Fuel Enrich valve and holding full throttle. Once it fired I kept holding the fuel enrich valve and kept the full throttle applied. It acted like it was struggling, spitting and sputtering. About two minutes of rough running, it cleaned up and worked fine. I stopped and restarted it a number of times with out any problem. Ran it for about 20 minutes.

I figured that I had a problem with water in the fuel. I installed a fuel separator and a new fuel filter.

Yesterday I took her out again. To check the traps, which at this point have been in the water for two weeks. Same thing. And I mean exact thing. The boat even died in the same place in the water. Same story. Got past the "No wake" and went to WOT. She ran all the way to 4500 - 5000rpm and died. Took her home and was able to get it running again. I looked at the fuel system there is no problem with delivery to the carbs. I looked at the coil packs and the switch packs. Noting is disconnected or obviously damaged.

To get her running again, it took some WD-40. (Yes I know it is bad) She fired erratically, then I get her running steady again, and like before it spat and sputtered. In about 2 minutes it cleared up.

I am sorry about the length of this post, I figure the more info that I can give you will help. I am lost. I have no idea what to next.

I welcome any advice on what to try. And if you are in the Pensacola/Perdido Key area and would like to make some extra cash I am more than willing to pay a qualified mechanic to come to my house and take a look at her.

Thanks so much I eagerly await your replies.

Matthew Simmons

 

[gss036]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

I think I would borrow a couple of 6 gal portable tanks and try running the motor on those to see if you have a problem with the fuel tank. Something blocking the untake, sucking it up as you increase speed, thus fuel demand. Have you recently started to burn the new gasalcohol? Might have really cleaned outy a lot of junk in the fuel tank.
Sure sounds like a fuel problem.

 

[andy6374]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

If you hold down the enricher valve and it keeps the engine going then it sounds like a carb problem, ie this bypasses the carbs.

Have you tried disassembling and cleaning them? (you can't really clean them unless you disasemble). Carb gasket kits are really cheap and I bet the switch to E10 gasoline has loosened up varnish in your fuel tank and is now clogging up the carbs. Don't keep trying to run it if you have lean jet.

 

[LubeDude]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

This sounds like a classic example of a plugged vent tube. Bees and other things will sometimes build nests in there. How they stand the fumes is beyond me. Check it out.

 

[mbtskysurfer]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

I am going to check all these things today. I am interested in the vent tube aspect as I saw some white foam in one of the block vent tubes on the engine the first time it acted up on me.

I have done my share of engine work. Transmissions, cracked heads. However I am new to this whole two cycle world.

I do have a question, I am a computer guy and don't pay attention to what is really going on in the world of gas. Why is it that everyone thinks that I have switched to gasalcohol or E10. I just get my gas from the pump at the Tom Thumb here in Pensacola when I go out. Has there been a change at the pump with regular 87 that I am not aware of. I know this may sound like a stupid question, but it may help me understand what is going with the engine.

Thanks for all your advice, I will post tonight and let you know what my testing shows.

 

[andy6374]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

I believe LubeDude was refering to the vent on your gas tank.

Here are some good reads on E10. It's happening all over and it's probably in Florida by now. When you are filling up your car/truck does it say that the gas contains 10% ethanol?

http://www.proboat-digital.com/proboat/200608/

click on contents and scroll down to "Pain in the Gas"

 

[steve694]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

Guys (and Gals),

It is not often that I find myself with absolutely no clue what to do. Yet I find myself there with the Mercury on my Cape Horn.

Let me tell you what is happening and I will leave it to your very capable knowledge to help me get this thing running again.

This summer she gave me a problem not running over 2000rpm even at WOT. After much frustration and a lot of cussing I started to replace parts. As I am sure everybody with an outboard does in the beginning. I have replaced the spark plugs, fuel lines from the tank to the bulb and the bulb to the Tank/Oil Pump/Fuel Pump Tee. (Yes I took out the quick connect on the engine). This did not help at all. Next we tried the spark advance, put new switch packs. This helped. I got the boat to run at 5000 - 5500 with no problems for about 5 minutes. Then she would slip back to 2000 rpm and do nothing. I took her home and drained the whole gas tank by hand (150gal) what came out vaguely resembled gas. I replaced the fuel filter, filled it back up, and put StarBrite in the tank.

It was great! She would do what ever I wanted. Took her out on three full day trips. I had finally licked my problems. I was a happy boat owner.

However.... (it seems there is always a however)
Two weeks ago I put the boat in the water to go check my crab traps, like I had done three days before. She started normally. I got out past the "No Wake" area and took her up to WOT. She climbed as normal up to 4500 - 5000rpm and died. I don't mean died back to 2000rpm. I mean she died completely. She would not start at all. I had to be towed in. I took her back to the house and the next day I began working on it. After almost 30 minutes of turning it over. I finally got her to start, I did this by holding down the Fuel Enrich valve and holding full throttle. Once it fired I kept holding the fuel enrich valve and kept the full throttle applied. It acted like it was struggling, spitting and sputtering. About two minutes of rough running, it cleaned up and worked fine. I stopped and restarted it a number of times with out any problem. Ran it for about 20 minutes.

I figured that I had a problem with water in the fuel. I installed a fuel separator and a new fuel filter.

Yesterday I took her out again. To check the traps, which at this point have been in the water for two weeks. Same thing. And I mean exact thing. The boat even died in the same place in the water. Same story. Got past the "No wake" and went to WOT. She ran all the way to 4500 - 5000rpm and died. Took her home and was able to get it running again. I looked at the fuel system there is no problem with delivery to the carbs. I looked at the coil packs and the switch packs. Noting is disconnected or obviously damaged.

To get her running again, it took some WD-40. (Yes I know it is bad) She fired erratically, then I get her running steady again, and like before it spat and sputtered. In about 2 minutes it cleared up.

I am sorry about the length of this post, I figure the more info that I can give you will help. I am lost. I have no idea what to next.

I welcome any advice on what to try. And if you are in the Pensacola/Perdido Key area and would like to make some extra cash I am more than willing to pay a qualified mechanic to come to my house and take a look at her.

Thanks so much I eagerly await your replies.

Matthew Simmons

 

[mbtskysurfer]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

Ok, so here is an update.

I went out to the boat to start working on. I thought I would pull the plugs and take a look at them. While messing around at the back of the engine I happened to notice the new switch box that I put on the boat two months ago. It was burnt up. It was so burnt that the IC board melted inside of it and the silicon residue dripped down to the second switch box.

I replaced this box with another one. I did take a look at the old switch box it seems that it was burnt in the same place.

Does this point to a bad Stator?

 

[sleepinin]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

That's not a switch box it's the voltage regulator. I don't know what would cause both of those to burn like that but I'd guess you didn't put the heatsink grease on it when you mounted it. You also might not have gotten them grounded? I'd also check the stator and the real switchboxes before spending anymore money as I think those voltage regulators are about $120 each. Order a service manual and most of this will become clearer. You'll also need a voltage meter. You can also go to mercurymarine.com and go to the parts express section and enter your seriel number and you'll see the schematics with labels of what is what.

 

[mbtskysurfer]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

I have a service manual, and I have a voltage meter. I did not really pay much attention to the nomenclature of the two the first time that I did the repair. I remember now that it is the Voltage Regulator, thank you for your correction.

I did not get any thermal grease with the regulator when I bought it. Nor did I see any on the one that I pulled off. The regulator is spaced off the block with a spacer on the bolt and then another spacer to the plate holding the coil packs. I am a little unsure where the thermal grease would go.

As far as this specific regulator goes it does not have a ground. If you look in the photo there are five wires (2 red, 2 yellow, 1 grey). Both pairs of the red wires and the yellow wires are connected to various parts of the engine. The grey wire is capped with a rubber terminal cover. I have covered that grey wire on both the two new regulators that I have installed.

What else could cause this regulator to burn up like that?

Thanks for your help. I am going to try it out tomorrow. I will let you guys know what it does.

 

[sleepinin]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

I was guessing that your year model was close to mine but it may not be. My voltage regulators are placed directly against the engine with heatsink grease between the metal on the engine and the metal on the regulator. They are then followed by a spacer and then the plate that holds the coils on. If yours were mounted out away from the engine then that's probably the way they were meant to be. You might verify this in your service manual. The original doesn't have a ground it just uses the mounting bolts but the aftermarket ones like sierra should have a ground that you can connect to be sure your grounded. That would narrow it down to a ground or stator problem (or something else that I haven't thought of).

 

[mbtskysurfer]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

Grrr.

Today I took the boat out, sure that the voltage regular that I replaced Saturday afternoon would be the problem. In a word. NOPE.

I put it in the water, and started it right up. Backed her off the trailer with no problem. Got her on the dock to wait for my father who was with me to get to the boat after parking the truck.

He got on board and I put it in Forward and gave it a little throttle. And she died. So I cranked her up and tried again. No joy. Luckily I was close enough to throw the line back to the shore and have my father get off the boat and hold it near the dock.

While I was in the water I thought I would do a little on the spot testing. I am not sure if this was a good idea or not. But this is what I found out. The boat will go as fast as I will let it in reverse gear. However almost as soon as I apply a little throttle in forward gear the boat dies. It is almost like there is something in the system telling the engine that I am in forward gear and to die. After much frustration I finally got the boat back on the trailer and took it home.

Back to the service manual. I did not find anything that was hooked up to the forward gear, so that theory is out.

I am going to run an ohms test on the Stator and the Trigger tomorrow.

If this is way off base I would love if you could help me.

[Sleepinin I have 91 BlackMax 200hp, I think we have the same engine, your help is much appreciated.]

 

[andy6374]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

To the ohm test. Then...
Do some quickies first. Run a compression test and spark test. If those check out we will move to fuel.

Usually when engines die when put into gear its either.
-The idle needs to be increased.
-Overpropped
-Dirty carbs.

 

[studlymandingo]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

From what I understand, there is an area that begins around Point Clear, runs west of Orange Beach, then to a triangulated point south of both that is likened to the Bermuda Triangle. Sounds like you have been caught up in its force!

 

[mbtskysurfer]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

Ok, I ran the ohms test on the engine. The Stator tested correctly, however the Trigger shows no continuity on the meter. The book says it should run 11 - 14 at Rx1.

Could the Trigger be bad to the point that there is no continuity. My manual states that it is important to check the grounding of the switch boxes. And that tested correctly. However on three wires from the trigger there is NO continuity.

I am going to order a new one, unless someone on here has better advice.

Thank you again for all your ideas and help.

 

[sleepinin]

Re: 200HP 2.5L Mercury Dies at WOT will not restart. Please help.

Mathew,
Your engine is a little different than mine (99 model) so now I'm really guessing but do you have a Low Speed/ High Speed Spark Advance Module? How about a Idle Stabilizer Module or an Idle Stabilizer Shift System? When you described your experience at the dock that struck me as one of those items. I would think the bad trigger coil would have showed up in testing the spark, but by your readings it does seem bad. You can also check Trigger voltage by setting the voltmeter to 20vac put one probe on the switchbox trigger terminal and one on a ground. If no voltage than reverse your probes to check for negative voltage. If still no voltage than the trigger coil is bad.