Mercury 200 doesn't run good in the water

[SilverSS07]

Got the boat out for the first time today on the water. Didn't go so well. Motor is a 1988 2.4l Mariner 200. Runs great on muffs. From the second it started in the water it didn't sound like it was running properly. I had to give it a lot of throttle in neutral to keep it running- and not at a high rpm. Wouldn't rev high in or out of gear. I also discovered that it isn't charging the battery and tach was reading all over the place. I assume the battery not charging is the voltage regulator. The carbs were rebuilt recently prior to me buying it. I've rebuilt the fuel pump, replaced poppit valve, water pump, and thermostats. I'm planning on taking the carbs off tomorrow and taking them apart to see how they look. I checked spark with a timing light on all 6 cylinders and it showed I had spark. I was going to check compression but when I took the plugs out 2 of the plugs had a lot of metal shavings in the threads and then would not screw back in tight. So have to fix that first. Also my compression gauge broke when I was testing the 1st cylinder lol. Anyways- does it sound like a carb problem to you guys? Kind of seemed like the engine was getting too much fuel to me. Thanks for the help.

 

[racerone]

Obviously it only " sounded good to you " on the muffs.-----They bark and roar quite well on 4 of 6 cylinders.----Sort out the metal shaving bit first and do a compression test.--------No point starting anywhere else.

 

[Dukedog]

going to check compression but when I took the plugs out 2 of the plugs had a lot of metal shavings in the threads and then would not screw back in tight. So have to fix that first.

not a carb problem... might as well pull heads ta check whats happenin' in those two holes.... sounds like sleeves may be in your future......sorry.

 

[SilverSS07]

Racerone that's kind of what I was thinking- start from the top. Dukedog I hope you're wrong! lol. Pulled carbs and inspected. Didn't see anything obvious but have them soaking in cleaner now. Ohm'd rectifier and it was bad. Pulled head and didn't see anything obviously bad. Cylinders had minor pitting. Got a heli coil for the plug holes and put the inserts in and put the head back on with a new gasket. Will get a new compression tester and see where we're at when I get off work Thursday.

 

[SilverSS07]

Ok guys. Got heli coils in the 2 lower plugs on port side. Just a note for anyone else who has to do this- pull the head. I read about packing the tap with grease to catch metal shavings... tried that and stuck my finger in the plug hold and felt a ton of metal shavings. Pulled the head off then to clean it out good and tap the lower hole. Compression readings were done cold with carb's off the motor. New head gasket on port side.

port starboard
140 135
138 135
145 138

Going to check the reeds out since the carbs are off. Pistons looked good with very little carbon buildup. Cylinders had minor pitting but otherwise looked good. I ordered a DVA yesterday for my fluke. Also ordered a Clymer's manual. Suppose it's better than nothing. Searched the internets for hours and been watching ebay for a few months and can't find a factory service manual for sale. Thanks for the help

 

[SilverSS07]

Reeds look good. Now gotta find a gasket lol

 

[SilverSS07]

Got my new reed gasket yesterday. Hopefully will have time to put everything back together tomorrow. I also got a new rectifier and rebuilt the carbs. I didn't see any dirt or anything in the carbs but they are definitely spotless now. Something I noticed is that the top 2 carbs are different numbers than the bottom one. Is that normal/ok? Top 2 are WH39-1, WH39-2, and bottom carb is WH22-3. My Clymer's manual doesn't even list WH39 carbs as being in existence lol

 

[Dukedog]

39's were mostly on tha hi perf 2.4's, ie: bridgeports, although some found there way on production 2.4 200's... 22's are production 2.4 200 carbs also.. but ya need all three ta match with right production jettin' which ya need ta check since tha mismatch is an indication of some backyard hot roddin'... either 22's or 39's.....

oh yeah, dump tha clymer and find ya tha oem manual..........

 

[SilverSS07]

Yeah I'm still trying find an oem manual. No luck yet. So as long as the jets are the right ones the carbs are ok?

 

[SilverSS07]

Jets are .082 in cyl's 2 and 5, .080 in the rest.

 

[Dukedog]

22's are 76 in 2 and 5, 74 in 1, 3, 4, 6.....think all idle's are 46's..... 39's a little different.. think all mains are 80's and all idles are 56's.... how it acts with different series (mix series) i don't know, as i've never done that........

enter this on ebay.....

oem manual 97658 3

 

[SilverSS07]

Thanks I found a manual. It's on it's way. Well I know carbs are clean so I'll probably put them back on when I get a chance and take it back to the river and see what happens. Going to make sure everything is sync'd and that timing is advancing.

 

[Dukedog]

might watch for single 39.. will need ta be tha bottom 'cause of enrichment bib.....gl

 

[SilverSS07]

Got everything back together and took her to the water today. Still doing the same thing. Not revving like it should, dying in gear, etc. It is smoking A LOT. I premixed @ 50:1. I premixed my V4 Evinrude and it didn't smoke nearly as much. There is smoke coming out from around the powerhead and coming out from underneath the cowl. Is that normal? I found out that the mid section is off a 1986 150. Is there a possibility of something being wrong with the exhaust maybe causing too much backpressure? I noticed quite a bit of a milkshake looking liquid around the midsection where the motor bolts to the transom. I put the dva on both red wires to switchboxes and it showed about 30k, both blues showed about 102k. Are those readings normal? Thanks for the help guys.

 

[Chris1956]

Check for an exhaust leak where the powerhead connects to the midsection. Smoke from that area indicates a leak. That would starve the motor of O2.

My 135HP Merc had a rubber hose for idle bypass exhaust. It was knocked off and the exhaust was able to get into the cowling. As a result, after a high speed run, the motor would not idle well, due to a shortage of oxygen. Took me a bit to find that issue, as I was chasing heat soak issues.

 

[Dukedog]

no smoke from ANYWHERE but exhaust... nothing from anywhere around tha block... ya got a problem with adapter plates... could be gaskets and/or something not "flat"... milk shake stuff is water mixing with fuel where its not supposed ta be... tha size of tha exhaust is tha only difference in tha plates... tha 150 plate has larger exhaust holes than tha 200 block... you can get away with runnin' that way with tha metal reinforced power head gasket (for awhile anyway)..some try ta use tha cheapo when they do tha 200/150 thing and it just last a very short time... other wise ya need ta find a 200 plate (both pieces).. but sounds like it may be both power head and adapter plate gasket (one between tha two adapter plates) or as said "something not flat".....

'll hafta look for tha stator ohm readings and dva stuff (i'm gettin' really old)... ya might find it on CDI's site.. '88 200 should be 16 amp.....

justa note... when ya put new gaskets (ph and adapter plate) on, tha power head needs ta be torqued down a little at a time ina clockwise direction or chris cross pattern like ya would do a head.......

 

[Dukedog]

one other thing... could be cause of tha "milk shake"... when ya get tha adapter plates separated check for excessive wear on motor mounts and their cradle on both plates.....

see if you can see tha piston tops (will be really clean if had water injested, even jus droplets) on tha bottom two cylinders.... tha only way those gaskets being bad that would effect tha way tha motor runs is if its getting' a touch of water into either of those holes.....
another test on tha regulator... ya seem ta think its bad?... disconnect it and run tha motor.. won't hurt a thing...tach actin' stupid is probably tha rectifier.... could be tha stator causin' tha runnin' problem.... can't find my stuff so go tha CDI website for testin' 'lectrics with ohm meter and dva.....

have you had this motor/power head for awhile or is this your first venture with it runnin' ona boat?.. no tellin' whats with it if someone built it with miss-matched carburators.....

 

[SilverSS07]

Thanks for the reply. I bought the motor a few months ago "100% ready to go" and mounted it on my boat. Forgot to mention I put a new rectifier on it and the battery is charging. Tach still acts a little weird but better than before. So the running bad is probably not caused by the exhaust? When I replaced the head gasket all the pistons on that side looked about equal.

 

[Dukedog]

Thanks for the reply. I bought the motor a few months ago "100% ready to go" and mounted it on my boat. .

so does this mean that you have ran tha boat and motor ona lake before with no problems?....or did all this show up first time it went to tha lake?... how do you know its even a 200 and not a 175 or 150 since it seems ta have come from a hack?

were tha cylinders chrome or steel?... horizontal or vertical reed front half?

have any pictures of tha power head?

 

[ROY ASHLEY]

Just had a mercury 90 over hauled. When I go fishing and stop for 10 or 15 minutes or so. I have to pump my bulb again to get it hard. No trouble after that unless I stop and sit for a while. Can someone help