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  1. #1
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    1984 Mariner 150 loss of power / bogging down while accelerating

    I'll try posting this in the right forum now .


    Lets start with the information overkill:
    1984 Mariner 150
    Model Number/ Serial Number: 7150724/06466160<O</O
    19p 3 blade Alum prop
    Thunderbolt III Ignition system
    advanced oil system with 3 gal oil Resevour
    Carbs: WH-27 1,2 and 3
    Jet sizes
    6 Primary jets(high speed) .064
    6 Idle Jets .054
    There are NO intale venturi jets on these carbs.

    I live in New Mexico, I normaly operate this boat at 4200 Ft elevation. I live at 6200 feet. The boat came fron sea level. I know the Seloc manual says. size down the main and idle jets .002 for elevations 2500 to 5000 feet. Could this be a major factor? I have done nothing to them as of yet.
    The jets are Mercury spec size. for 0 to 2500 feet.
    I could not find smaller jets of this size anywhere. A local carb customizing shop recomended soldiering them closed and drill press them to the smaller diameter hole.
    <O</O
    OK, I must tell you I feel like im chasing my tail! This is a long post I’ve read a lot and done a lot to this motor already.
    My motor looses power at around 1800 RPM. When I hit 1800 I have to stop moving the throttle, If I give it more throttle the motor will bog down and loose all power. I can some time, not all the time choke it while increasing the throttle and get the power head to get past the 1800 rpm hump and rev up to 5000 RPM . Other times it bogs down and dies as if i were not choking it. When it gets past this mid range hump, it purrs. Maybe one out of 20 times I can get it up on plane. The angle of the motor is critical when doing this it needs to be tilted all the way in the down position roughly 8 to 10 degrees past level(after setting the floats to spec's). If I keep it there long it will not idle right, it will die . It idles at 800RPM fine when level and increases to 1050 when the exhaust ports are out of the water. The floats in the carbs are not all exactly alike the are minor differences in their shape and color, the metal tab on some are brass and the others appear to be made of stainless or nickle plated brass they appear to have been replaced somewhere in the carbs lifetime. I can’t seem to find replacement Floats for this carb anywhere. the carbs are WH-27’s .
    Anyone know where I can get replacement floats for a WH-27 carb?? I cant find them anywhere.
    I have replaced the stator twice, trigger once(last time with CDI components nice! I noted quality of manufacture was present) rectifier once. Removed and cleaned the carbs 3 times. I was never able to get the boat up on plane with the first stator. After replacing it with a CDI stator I got it on plane once. I know that the switch boxes work or they don’t. So im not going to replace them. The issues are not pointing to them. I installed an inline fuel filter in the sullpy fuel hose before the bulb, the second time I took the carbs off to clean them. I purged all the fuel lines and tank. Now, the last time I pain stakenly took 3 hours to set the 6 carb floats, WH-27’s. Now, this was the 3<SUP>rd</SUP> time I took the carbs off. I only ran the motor for 2 hours before removing them to set the 1/16" gap on the floats. (I found more crap in the carbs. after installing the inline fuel filter) My Seloc Manual instructs to set them to 1/16” movement. To Any one reading this, is this right? Sure looks real choked off to me. Allthough I noted a significant increase in power after following the float setup in the Seloc manual instructions.
    Can any one get me good instructions on the proper procedure for setting the floats on these carbs. PLEASE!
    The only thing that has made any real diffrence was when I monkeyed with the carbs the last time. I was perplexed because I was still finding crap in the carb! Small debris in the larger fuel brass venturi the smaller tube that leads up from the float chamber sets in. (The light came on! The oil injection system intersects the fuel line after the motor inlet. This had to be where the crap in the carbs was comming from. Or another thought.... the floats are flaking apart...kinda looked the same color as the floats, not sure yet. More to follow on this….) <O</O
    <O</OThe last time I removed and cleaned the carbs (I also removed the plugs and wiped them clean of the oil fouling) it got up on plane the first time. It worked well for the first 4 hours. Thought I had it licked. Then as the day went on it went back to doing the same thing. Untill it would continue to loose power at 1800 (9 miles per hour) and not get up on plane.
    I have been playing around with the oil mixture. I had to insure that oil was getting in the system so I would mix fresh Mid grade 90 octaine gas with the 50:1 ratio of Mercury 2 stroke oil, I found the power head had more power. I know mixing the oil in the tank at 50:1 is not helping my plight. But what else can I do. I have not disconnected the oil system yet because it’s there, and Id like to have it work right. The way it was designed to. The motor runs smother with more oil in the gas, but their is one problem with that. The spark plugs foul up quick. This itself ALSO causes loss of power.
    I also believe this is another one of the contributing factors. Plug Fouling from excessive oil mixture.
    After about 20 hours total running time, replacing most of the major ignition components. I have determined the only thing that has made a major difference in motor function was adjusting the carb floats. Then it dawned on me again. OIL! the oil system. When I went and checked the 3 gal oil tank while at the lake this last week. I found a thick coating of what appeared to be a vasoline on the main oil tank screen. A marine motor tech told me about the problem with TW-3 oil additive coagulating into a vasoline looking substance. He said to check and clean the screen before every outing. I removed all the old oil cleaned the screen it looked like someone smeared a thick coat of vasoline on the screen. I replaced all the old oil with new oil. Purged the old oil from the hoses and power head oil tank and the oil metering pump. This gunk was obviously causing oil flow blockages, in the oil delivery system. It would appear when this thick oil (vasoline looking stuff) broke off the screen and entered the system it would clog up the oil pump and eventually enter the jets in the carbs and I would loose power untill it was flushed out with gas over time as fule passed thru. I would regain power again and get up on plane. It would them plane fine for a while then start the bogging all over again till the plugs were so fouled it would not idol right.<O</O
    But in the mean time im running 50:1 oil in the gas. This rich oil mix plus when the oil distribution system decides to work right it pumps more oil into the motor making the mixture about 25:1 ratio. Yeah real smokey and rough running. I believe the oil delivery system is a major factor hear. Still have to investigate the oil pump further but lack the knowledge. Seloc is limited in this area. This is where the masters of Powerheads come in. HELP!!
    after thoughts:<O</O
    ****When I trailered the boat, remove and clean the plugs, put it back into the water it would plane fine, the first time every time. Then after running it a while plugs would get oil fouled and loose power. (I know to rich oil mixture)
    With this being the case I truly believe this problem lies with a motor that is extremely sensitive to the oil mixture it is receiving from the system.
    The factory specs say oil metering system is designed to give 50:1 at idol and 100:1 at WOT.
    With that in mind I know that the 25:1 ratio fuel/oil would foul the plugs fast at WOT and thus I would get a loss of power.<O</O
    So, the problem lies hear. If I run the motor and im not adding oil to the fuel I risk power head burn out. If I run the motor with 50:1 gas oil mix and the oil pump decides to pump oil I will foul the spark plugs.
    I attempted to run it on one tank without mixing oil. I ran like spottering and back filing. after 5 min of that I added oil 50:1 to the fuel tank and it smoothed out. <O</O
    .....Grumble.....makes trouble shooting a genuine task!
    I believe im on the right track. But time will only tell.<O</O
    I have not read any definite resolution to this problem on any site anywhere on the net. <O</O
    I believe it lies in the oil disturbtion system or Carbs or both. The powerhead is extremely sensitive to the oil mixture being pumped into the motor.<O</O
    Light mixture oil (thin) it labors to hard and fails to get on plane. To much oil and i get loss of power from plug fouling.
    As far as the cylinder compressions go. I know for a fact, as long as the cylinders do not have more than 20 psi difference, the power head is fine. Mine are as follows 82, 82, 78, 76, 80, 81. thats PSI. they stayed the same after i ran it without mixing the oil in the fuel . Yeah I checked em again. woof..... I was relieved . I know these compression readings are not real high. I've also been told when new, they normally registered 165 to 180PSI. Is this part of my problem?
    When it dose plane, it screams and flies at 45 MPH at 5000RPM with plenty of power . (thats screaming and flying to me)<O</O
    I notice more power with fresh clean plugs. That don’t last long. How do I trouble shoot the oil system with out adding oil to the gas? And or with out shutting down the oil injection system.<O</O
    I don’t want to burn out this power head trying to isolate an oil delivery system. That’s why im mixing the oil the way I am.<O</O

    Forgive me if i ramble.. I'm just perplexed.
    <O</O
    <OI will not give up on this powerhead yet it shows promises of a good working motor.</O
    <O</O
    Any and all suggestions are welcome.

    Any of you master techs please feel free to jump right in. I’m all ears!

    If you have any suggestions, that i get another motor, you can mail me a check and i'll be glad to purchase one. Just joking... I really dont want to hear that.
    <O</O
    Thanks for your time and help.<O</O

    I havent tried changing to a 17p or 15p prop. Are these to small for this motor?? Should I even attempt it.
    the 19p I have I can only get 4800 to 5000 PRM. Should I try a diferent prop before I have this worked out??
    Im really not conserned with a lightning hole shot. I just want to get the boat on plane everytime. Not hear the bog out at 1800RPM. Humm somthing to think about. humh?
    <O</O
    Dave_hunting for a solution for this Power head that still has some life in it.

  2. #2
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    I really hate to be the one to burst your bubble, but.......

    Compression, or lack of, is your major problem.

    You have a very good ignition system to get it to start with compression that low.

    Generally Mercs/Mariners do not want to start when pressure start dropping under 100 and progressively get worse is the rings/cylinder wear.

    Mic the cyl's and pistons and see if you are lucky enough to be within spec to re-ring and restore compression, otherwise bore and fit new pistons and it should run like a new engine.

  3. #3
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    Motor problems

    It sounds like a tired motor to me. One thing that I have found is that different compression guages read differently. I use one that doesn't have a hose on it and it screws into the spark plug hole. I think that you have some carb issues with the floats. Does it have the round floats? If it does I might have an old set of carbs. Where in NM do you live? I live in the Panhandle of Texas and fish Ute all the time.

    Shooter1

  4. #4
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    Thanks for the response.
    Im in Albuquerque, I fish Ute as well. Allways clean up when I fish there. Cought 8 small mouth there 14" to 19". 7 walleye 16 to 20" range, the last time we visited UTE.

    The carb floats are kinda square. Attached is a mechanical break down of one of my carbs. Sorry I dont have a better Pic.

    I would agree with the other post that the compression is low. I ran my last mercury for 10 years. Th compression was 85 and it stayed there till i sold it. I take great care with my motors and give em a lot of TLC. I never had any real problems with compression before as long as the were within 20 PSI of one another.

    I have been told by several marine mechanics more copmression is desireable but the motor should function with these PSI's.

    Ring set would'nt be a bad idea. Hone out the cylinders. Replace the reeds set. If i go that far I should just rebuild the whole power head.

    I just bought the boat in May. It was missing the stator and other components. When I installed the new one, Since the old one was missing. I orientated it as all others i have ever owned. wiring harness aligned up with the triger. The ignition system is great...now no real problems to report. Plenty of spark.

    I have no base board to start from, since I have no history with this boat motor combination. The broken LU that came with it had a 19p prop attached. I have to ASSUME. ( i hate having to use that word ) It operated fine on the 19p before the former owner broke the lower unit.

    The motor sat in SC for over 6 years before i bought it.

    Like any other motor that has set for a long period of time, rust on the rings might be a big contributing factor. I was hoping to run it rich on oil for a couple of tanks to help rid the problem. I can see no scoring or pitting on the cylinder walls as of yet.

    I had to replace the LU when I bought it. I matched what I had with a simular alike gear ratio of. 2:1. Im starting to think that a 17p or 15p prop might be in order. If the motor is tired I could alieviate some of the load by reducing my prop pitch. Since I can only achieve 4800 RPM at WOT, with the 19p Prop I have on it now. It is a thought.

    I'm almost convinced 90% of this problem is, I did not set the floats correct. The manual for this type of carb says thier should be 1/16" float movement. That is measured from the bottom of the float bowl to the upper surface of the float rim. Other posts say the float settings are not critical. I did see a significant, about 50% increase in power. It Idles better and when I do get it on plane it Hauls bASS.

    Still trying to figure out his puzzle
    Attached Thumbnails Attached Thumbnails 1984 Merc Carb.jpg  

  5. #5
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    Dave,
    When I set the floats on that carb I make sure that the float should be level or parallel with the gasket surface. I think that the fall on the float which you are setting @ 1/16" is not enough. Those floats should travel a 1/4" on the end opposite the pin. I don't have one here to look at right now but that is the best I can remember. Also do you have the idle stabilizer still on this engine? You might need to do the basic check the linc & sync.

    Shooter1

  6. #6
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    Thicker oil mix acts like a smaller jet to a point. More oil thickens the viscosity, so less fuel can get through the jets, thus leaning the mixture. Unfortunatly, too much oil with not enough spark will result in oil fouled plugs.

    Are you checking your float level by holding the bowl upside down and looking at how much the float is showing past the float bowl surface? Should see 1/16 of the float sticking out past the float bowl surface.

    What are you getting for compression?

    EDIT - I missed the compression readings 82, 82, 78, 76, 80, 81. That is pretty low but even, however, 6200 feet is very high. Not sure what that would calculate out to at sea level.
    Last edited by Propster; 07-25-2007 at 05:57 PM.
    1990 Cougar 25 MTR w/twin 300 PM's

  7. #7
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    My opinion, may or may not be worth much

    Compression that low probably wouldn't even start. Be sure your gauge is correct. If it is that low, that is your primary problem.

    It'll run 100 to 1 at idle, 50 or so at WOT. If the engine is in good shape, it should burn 50:1 Plus vro with no problem, in fact that is required for break in. I usually mix about an ounce of oil per gallon of gas in my main tank just for insurance. Don't seem to have any oil related problems.

    If the oil is that gunky, it's gotten contaminated, probably with a little water. Bacteria eat the oil, live in the water, and make the vaseline like gunk. Goes for both gas and oil, but oil is worse. I clean mine out thoroughly as annual maintenance, filter the oil I salvage from the tank, and use that for my thin pre-mix.

    I think the original floats were foam. They are completely junk. There is an aftermarket float available that's pretty good. I forget who makes it.

    If it were mine, I'd start with general health. If it's tight and has good compression, set the carbs bone stock, clean it all up and go through a formal link and sync, then see what ya got.

    Obviously, when you have chit getting in the carbs and plugging things up, adjustments are mute. It just don't make a bit of difference to worry about adjustments till it's cleaned up and staying clean.

    hope it helps
    John

  8. #8
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    J Martin

    Yes thank you. I'll check my compression gage. Because this motor definatly starts and idles like a top. It defanetly starts and runs when its has a fresh set of plugs and good fuel flow.

    I am going to replace the main oil resevour and hoses. Im thinking the junk was comming from the oil resevour and or lines. Ive alleady removed all hoses on the power head, replaced them, making sure they were in thier right and proper spots. I will pull the oil pump off the power head and clean it good. Im gonna replace the oil system check valve on the power head, just because I can. I'll go thru the fuel pump to make sure I sandwitched it togeather right.

    Im on the virge of a good running motor i can feel it.

    I was using Champion plugs. Im switching to the recommended NKG BU8H.

    I'll see if the local prop shop will sell or trade me a used prop for testing. A 17p and or a 15p. I hate blowing cash on a test.

    Any one got the factory, correct instructions for setting the carbs?? I used the Seloc manual but ther not carb specific. As far as I can see they are semi rare. WH-27's

    and any information any one can give me on aftermarket floats would be nice.

    I look at it this way. If after all this I have to overhaul the powerhead. I got everypart under the sun to make it work properly.

  9. #9
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    Shooter,

    No i removed that POS. As soon as I found out from talking to a motor head he said most preformance boaters ripped it off and caned it. So did I. When it was connected, the lowest I could get it to idle was 900RPM and it would bounce between 900 and 1300.
    Once I disconnected the idle stabalizer it settled and idled at 800 RPM smoothly.

  10. #10
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    I checked link and sync again. The timing is correct 11 degrees ATDC and WOT is at 18 Degrees BTDC, with the butterflies wide open. Right on the money. I'll start with the carbs, i'll remove them this weekend and readjust them. I will set the float fall, parrell with the gasket seat, with the bowls set upside down.

    I am an HVAC technition and your right my pressures are diffrent up hear. probably 10 to 12 PSI diffrent on the top.
    A good vacume at sealevel is 29 (28.5) Hear a good vacume is 27 on a good day. On the other hand it is harder to achieve higher pressures up hear too. they will appear a little low to those that live in other lower locations of the country. Yes my house is setting at 6200 feet. So most of my adjustments are set hear at the house. When I get to the nearset lake I can open the motor up, Santa Rosa Lake, it's at 4600 feet. It may mot sound like much, but I have to fiddle with all my motors when I get to the lake so they idle right. It normal for me.
    My last motor was a 1983 merc 80, the compressiom on it was 80,80,80 and it worked for me for 10 years with no problem.

  11. #11
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    J Martin

    Your opinion and all others opinion are welcome and valued by me!!
    And much appreciated!

    I've enjoyed reading all your guys posts over the last 2 months. It only took my stuborn Bass 2 months to start asking questions. I wanted to collect as much data as I could before posting questions.
    I made a go of it with only the help of a book. Most of the time it works. This time im banging my head on the wall!!
    My Seloc manual dont give me and feedback when I got questions!

    The motor starts and runs now, I see progress. But it just dont run right....yet. It didnt run at all when I got it. As this goes I will continue to post, till I get it fixed. Dont get boored with me guys. Put on those thinking caps and bare with me. I need all input and will consider all sugestions.
    It's just a motor! A man built it. And another man can fix it, that man could be me.

    Dave

  12. #12
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    Dave,
    With the stabilizer off you need to up your WOT advance to no more than 25 before. I usually go for 23 for insurance. I think you will see a difference in your motor with an extra 6 degrees of advance. I had a motor that was dogging last month that I changed the timing to 23 and he thought that he had a different motor. Before you make any adjustment be sure and verify tdc with a dial indicator and your flywheel cover pointer is correct.

    Shooter1
    Last edited by shooter1; 07-25-2007 at 10:04 PM.

  13. #13
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    Shooter<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
    <o></o>
    Thanks for your input. Maybe when I get this thing together. If I get this thing going we'll see about meeting at UTE Lake. We'll tear up the fish and have some more fish stories to tell. I forgot to tell you about the 8 lb 23" Walleye I caught at Conchas, on the 17th of July. I got Pictures!!! <o></o>
    <o></o>
    I’m using a good mic, It is precise. And have verified twice that TDC is 0 and the .463 mark was right on!<o></o>
    Ill set the WOT to 23 BTDC and verify the 11 ATDC at idle stop. I'll have the carbs off and clean them again tonight, and re-adjust the floats. Clean out the oil resevour and hose.<o></o>
    <o></o>
    I’m really not familiar with the Advanced Oil Delivery System.<o></o>
    QUESTION: should the advanced oil system hoses be as short as possible. Like you do a fuel line. It looks like i got 4 to 5 feet extra hose thats not really needed. Can I shorten them, without disrupting the system?<o></o>
    At these higher elevations I know from experience I have always make the fuel hose as short as possible, because its harder pull fuel thru a small hose at higher elevation. Just wondering.<o></o>
    <o></o>
    If I can get it this thing 100% clean, and everything back together. I'll talk the wife into a trip to Cochiti Lake this weekend (45 miles north of Albuquerque). We'll see soon if these tweaks work. <o></o>
    Im itching to get it squared away. <o></o>
    <o></o>
    Im still looking for a good compression gage. I'll go to Napa and see what they got.

  14. #14
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    The lenght of the hose is not critical, what is critical is NO SHARP BENDS OR KINKS and make sure all ends are tye wrapped. To me I want just enough to be able to move a little without disconnecting.

    Shooter1

  15. #15
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    Dave,
    The Mercury part number for the new float is 1395-9267 NLA

    I found one new old stock at twin city outboard . 14 bucks

    http://www.twincitymarine.com

    952 496 1951

    GLM is supposed to be making replacement floats.
    P/n 77280

    http://www.glmmarine.com

    I haven't found any yet.

    The old ones were a brown foam chit. The new ones are a blond hard plastic, and aparently never fail.

    hope it helps
    John

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