Mercury 200HP Outboard - Bogging

[wcsd106]

Last spring, I took my boat out for the first trip of the season and ended up sucking a small piece of twig into the carburetor for the #6 cylinder. To make a long story short, after removing the carb to get the twig out, I decided a rebuild of all 3 carbs was in order due to the fact that it had been at least 12 years since they had last been rebuilt. After rebuilding the carbs, I never got a chance to water test the boat again since I ended up moving shortly thereafter and spent the rest of the summer assisting my fiance with plans for our wedding in the fall.

Over the winter, I purchased an original Mercury Shop Manual to supplement/replace the Seloc manual I had purchased.

A few weeks ago, I got the boat back out and started getting it ready to hit the lake. Prior to putting it on the lake, I started and ran it several times on the driveway using the flushing muffs and garden hose.

The following procedures/tests were performed before putting it on the water:

1. Complete link-n-sync of the carbs/ignition. (Throttle pick up timing / WOT timing / Carb butterfly position all set to spec)
2. Spark plugs were replaced with new plugs due to their age and condition
3. Compression test was performed on all 6 cylinders. All 6 cylinders showed ~120lbs with no apparent signs of leakdown
4. Stator was tested for good measure (For the record, the Stator and both boxes were replaced about 2 years ago with new CDI Electronics brand parts)
5. Each cylinder was given a short spray of SeaFoam Deep Creep prior to the first attempt to start the engine

The engine started and idled well on the flushing muffs, so a water test was in order. I made a water test this past Sunday with poor results.

Results:

1. Engine initially had trouble starting, but once started, began idling well.
2. Throttle seemed sluggish...slow to respond to advancement of the throttle control
3. After idling out of the no wake zone, I attempted to throttle up but the engine would climb to about 2500RPM then slowly work up to 4000RPM. Boat would not plane.
4. I was by myself, so I was unable to try squeezing the primer bulb while the throttle was pegged to see if it was a fuel delivery issue.
5. Engine seemed very sluggish and seemed to lack power even when running at 4000rpm.

I returned to the launch ramp, put the boat back on the trailer and went home. I checked the fuel pump and engine fuel connector the next evening. The rubber O ring in the fuel connector was shot, so it was replaced. The fuel pump screen was slightly dirty, but was cleaned and then put back onto the engine.

I removed all 3 carbs one more time thinking that I must have not gotten them clean the first time. They didn't appear overly dirty upon inspection this evening, but they have been thoroughly cleaned again and blown out with compressed air. New gasket sets are due to arrive hopefully tomorrow and the carbs will be reassembled.

After the carbs were removed, I used an LED light to look through the intake to the reeds. They appear to be in good shape, but that is the extent of the testing I've performed on them.

When removing the carbs, I noticed that the lower side of the enricher solenoid fuel line was split (the line that runs from the enricher to carb #2 and on to carb #3. I purchased new fuel line to replace the split line this evening.

I also purchased new vacuum lines to replace the existing vacuum lines. The existing lines are still pliable, but feel brittle in spots. They are more than likely the original lines. *** Is this a good idea to replace at the moment? ***

I picked up a new fuel line connector this evening to use on an extra fuel line I have. My plans are to attempt to run the engine off of a different fuel tank to rule out any problems in the tank / fuel filter / fuel line.

Does anyone have any suggestions or comments on what could possibly be robbing my engine of power? The engine is a 1984 Mercury 200hp with WH28 carburetors.

I've always gotten good advice here, and thanks to help I received on this forum, I was able to get this boat and engine running great a few years ago. Thank you for reading.

 

[CharlieB]

Re: Mercury 200HP Outboard - Bogging

You found the bad O-ring in the fitting, good move, air sucking into the fuel system would not allow the fuel pump to completely fill the top carb, the upper two cyls can run lean, hot and melt pistons if not found.

It would still be a good idea to test the fuel pump, disconnect the hose to the upper carb, crank the motor with the lanyard pulled so it will not start, watch for a strong pulsed flow. Next temporarily replace that hose with a clear hose, start the motor and watch for air bubbles passing thru indicating you still have air sucking into the system. REMEMBER, remove the clear hose once finished testing as clear hose is NOT APPROVED or rated for fuel, only very short time testing.

A second thing I noticed is that you set idle timing when on the hose. Idle timing adjust idle speed and should be done with the boat IN the water to provide the proper amount of exhaust back-pressure. If your model carbs have adjustable idle jets, the mixture also must be perfected while on the water and IN gear. Few V-6 have adjustable idle jets, so this may not apply to your carbs.

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Charlie,

Thanks for your reply. As always you have good advice. I will pick up a piece of clear hose tomorrow and when I get the carbs reinstalled I will check both the fuel pump output and leakage.

My carbs do not have adjustable idle jets, but I will bring the timing light along with me next time I take the boat to the lake. I did notice that the engine started right up on the muffs but I had to advance the throttle when it was actually in the water.

If I lowered the engine into a large bucket of water, that should produce the same effect, right?

 

[CharlieB]

Re: Mercury 200HP Outboard - Bogging

You would need to submerge the prop and mid-housing to the level same as when the boat is in the water. Water fills the mid housing causing back-pressure in the exhaust. Once at throttle and underway that water level falls and at top speed is gone.

While you have your timing light out, clip on to each spark plug wire to ensure each is firing as one dead cyl can reduce performance yet still sound as if all are firing.

If is never a bad idea to test each plug wire for a good hot spark of at least 7/16 inch. Remove all plugs, stick them back into the wires, tape all the plugs together along with a short length of wire you can attach to a good ground, this gives the spark energy a path to ground. One at a time take each plug wire and test for a 7/16 inch arc to ground.

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Charlie,

I checked the fuel pump output at cranking speed this morning with the kill switch lanyard pulled so it wouldn't fire. I stuck the output line to a clear bottle so that I could watch it and at cranking speed I can see a pulse of fuel. I also replaced the vacuum lines this morning while I had access to them, though even the brittle ones still had a good seal and were holding air.

While I was out at the marine supply store, I picked up a new water separating fuel filter, the last one was dated 4/2011 (I write the install date on the filter so I always know)

I've got a adjustable spark tester. Will be checking for spark on all cylinders this afternoon. My carb rebuild kits showed up this morning and I've gotten the carbs reassembled and have 2 of the 3 reinstalled. Stopped for a few to grab a cold drink and check iboats to see if anything else had been posted.

If all goes well, I'm planning on testing it out this afternoon in the water, and will bring along the timing light. I am also going to try running it off of the fuel tank I keep in my jon boat since it has the freshest fuel. When I spoke with my tech today, he seemed baffled as well regarding this situation, he said that the fuel pump might be torn and flooding a cylinder, but other than that he didn't offer a lot of ideas.

Thanks again and keep your fingers crossed .

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Ok. Carbs have been installed and everything reconnected properly. Decided before taking it out to check for spark on all cylinders using the timing light.

Problem has been found:

The Starboard cylinders 1, 3, 5 have spark
The Port cylinders 2, 4, 6 have NO SPARK

I have swapped the Red and Blue wires on one of the ignition packs with the Red/Whi and Blu/Whi wires on the other pack. I then started the engine up again and checked for spark. Swapping the stator wires did not move the problem. I still have spark on 1, 3, 5 and no spark on 2, 4, 6.. .

I just put new packs on this engine back in July of 2010. Does it sound like I have a bad pack again?

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Just returned back inside from checking the engine one more time. I removed the Bias wire running from between the packs and that did not return fire to cylinders 2, 4, 6.

I did find something disturbing on the pack feeding cylinders 2, 4, and 6. The picture is posted below, what it shows is a crack about 1 inch long on the very bottom of the pack near where the ground wire comes out of the pack. The crack is pushed outward about 1/8 of an inch. Would this be what I suspect, a very pronounced sign of a bad cdi pack?

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Any ideas what would have caused the switch box to go bad? I replaced the switch box a couple years ago. Replaced the stator at the same time.

Thanks

 

[SparkieBoat]

Re: Mercury 200HP Outboard - Bogging

get a $30 DVA adapter for goodness sakes. CDI has a great free troubleshooting guide. CDI requires for you to DVA test your electronics especially the voltage regulator before installing their stator if you want them to warranty it or any other part.
The proper troubleshooting order would be
1 check engine compression
2 Check engine sparks with a spark gap tester, should be 7/16 gap blue streak on each cylinder.
3 If any spark issues do a full DVA test of each component.
4 If spark and compression are good then check timing/linkage
5 Check all fuel possibilities. Carbs, pump, lines/connections, tank pick-up and vent. Sometimes it is easy to get a small portable tank and a NEW hose and connect directly to the fuel pump bypassing all old connectors.
6 On Mercs, If your motor still has that timing advance module on it, Remove it and throw it away, far away, and adjust your timing to 24 BTDC. (late 80s and 90s carbbed motors)
that should just about do it.

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Thanks sparkie but most of that has already been done.

Now looking for things that could cause a switchbox to go bad before I replace it.

I have a dva adapter I purchased from patriot electronics on eBay. It worked great for finding my bad stator a couple years ago.

 

[SparkieBoat]

Re: Mercury 200HP Outboard - Bogging

well if all of your electronics check out ok and you got a new bad switchbox, sounds like you just got a bad switch box. The stator or regulator could damage the switch box, but if they are ok and as long as all your wires are connected properly and there are no shorts in your wiring, you should get a replacement switch box, it should be warranty issue. I like CDI parts because they will help you out. If thats what you got give them a call and tell them whats up. they will replace the bad switchbox.
by reading your post I thought you were just throwing parts at your motor trying to fix it without testing. I hate to see people waste money like that when a $30 DVA adapter can accurately test all their electronics.

 

[SparkieBoat]

Re: Mercury 200HP Outboard - Bogging

o yea, does your motor have the idle timing module?

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Sparkie,

The idle control module was removed a couple of years ago. The insulation had become brittle, and I was informed by people here that the module wasn't really necessary anyway. In fact, I was told it can cause more harm than good if it goes crazy.

I appreciate the help. I'm a rather frugal man and I don't throw money at problems if I can avoid it. I prefer to analyze and troubleshoot sometimes to the point of overkill lol. A couple of years ago, I replaced a bad stator and both packs that were bad. The engine ran like a champ after these were replaced. I thought I was having carb issues due to a piece of twig that ended up in my intake a year or so ago. I guess the pack went bad around the same time and I was so fixated on the twig that I didn't take a step back and look at every possible solution.

After cleaning and rebuilding the carbs, I fired it up on the driveway using the muffs and used my timing light to check for spark on all cylinders while it was running. Had 1, 3, 5 but not 2, 4, 6.. swapped the red and blue leads from the stator and the problem didn't move. Removed the bias wire and still had the same problem.

I've pretty much narrowed this down to a bad pack, but I am looking for what would cause a new pack to fail. I don't want to put a new pack on there and have it pop again. I am going to test the rectifier this afternoon as per the procedure in the shop manual.

Besides rectifier, bad/loose connections, and shorts is there anything that I should be concerned about that would pop a switch box?

 

[CharlieB]

Re: Mercury 200HP Outboard - Bogging

Disconnect and Ohms test each coil. A coil with significantly less resistance can place stress on a switchbox.

Merc boxes are recomended replacing in pairs, CDI boxes are O.K.'d to replaced one at a time.

You may have to call CDI, dig up your receipts so you know exactly how long the boxes have been installed.

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Charlie,

I will check each of the coils this evening as well.

I keep pretty good records and was able to locate my invoice where I purchased the switchboxes in July of 2011 brand new.. Should fall within CDI's 2 year warranty. I have sent in a RMA request and imagine I'll hear back from them tomorrow.

In the meantime, I was able to locate a used CDI switchbox for a decent price. I will more than likely install the used box and keep the warranty replacement box around just in case of future problems.

 

[SparkieBoat]

Re: Mercury 200HP Outboard - Bogging

Definitely check those coils, also inspect all wiring, making sure that you do not have brittle or cracked wires, other than that I would say may you just got a bad box. If your warranty replacement goes bad with in a few years, then I would really suspect something.

 

[CharlieB]

Re: Mercury 200HP Outboard - Bogging

Disconnect the black/yellow wire from the switchboxes, test for ANY voltage from the ignition switch. turn the switch on/of repeatedly, maybe disconnect the starter relaly trigger, yellow/red, so you can turn the key all the way to the start position.

If EVER ANY VOLTAGE to the kill wire B/Y from the ignition switich, this WILL damage a switchbox.

 

[SparkieBoat]

Re: Mercury 200HP Outboard - Bogging

great thought there Charlie.

 

[wcsd106]

Re: Mercury 200HP Outboard - Bogging

Thanks all for the help. I got a good deal on a used CDI pack and ordered it on Sunday. It arrived today. I spent the morning testing the Stator, Rectifier, ignition coils, etc. Everything tested OK so I guess I just got a bad part. I shipped off the old pack for warranty replacement from CDI this afternoon as well. I've been told by CDI that I should expect a 48 hour turnaround after they get my part. I figure I'll test the new part then put it away to keep as a spare since the used part is working good.

I now have spark on all 6 cylinders and the engine sounds worlds better when running on the muffs. I can't believe I thought it was running good before.

Unfortunately, mother nature may keep me off the water until Sunday, but I'm confident that my problem has been fixed. Might try to squeeze a quick run on the water tomorrow afternoon if I can do so between raindrops.

Thanks again for all the help I received in this thread. I've never been disappointed here at Iboats.

 

[Dukedog]

Re: Mercury 200HP Outboard - Bogging

Just a little tid-bit as you have found out. Any 'lectric part on a Merc can take a dump at any time, includin' new, for no apparent reason. Brand makes no difference either..............