1976 Merc 1500 Dead in the water!!! Help please!

[rriddle99]

:grumpy:

I have a 1976 Merc 1500 that seems to be alergic to water. I purchased a manual and tried all of the following:

1. Compression 125 on all cylinders
2. Spark Plugs correct
3. Carbs cleaned and floats checked and set
4. Fuel pump rebuilt
5. Link n Sync performed multiple times myself
6. Link n Sync performed by marina
7. All cylinders firing properly
8. Stator working properly

It sound and seem like it will run great on muffs and in a trough, however put it on the lake and it immediately starts differently (usually harder) and will not run well at all. I've only been able to get the boat on plane one time and then it seemed like it would just take a little tweak on the timing/ fuel ratio to dial it in however since then no luck and it mostly just bogs down. I have to push the throttle into gear and into half or more throttle position or it will just die. Even when it doesn't die right away it will sound for a second or two like it will take off then bog down and sometimes dies and sometimes just runs about 2500 with no way to gain speed, etc.

Please help! Pulling what little hair I have left out with this one and marina is at a loss thus far.

Thanks to anyone who has suggestions. I'm hoping this is not reed related as this requires what seems to be a complete power head tear down however everything else seems to be working correctly to the best of my knowledge.

:mad-new::facepalm:

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Your spark plugs are all the same color? Brown or black? Check the spark plug wires for arcing to ground. Carbs should be set 1-1/2 turns out from lightly seated. Final adjustment will be a bit more than that, but must be done on the water. Carb idle mixture needs to be a bit richer than what makes for best idle.

You did set the carbs to start to open at 4-6* BTDC? Max spark advance is 21* BTDC?

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Thank you for responding Chris and yes. I started with carbs 1-1/2 out and the one time I hit plane the carbs were all almost 3 turns out however each time I started testing in water I started at 1-1/2 out. Boat is currently at marina who will be doing more testing on Tuesday related to the reeds bleeding down (don't remember what this test was called... maybe secondary leak down?). I know for sure the max advance is set @ 21* and I think they told me they ended up with idle at 3*BTDC currently. When I got it to plane I had the cowls off and it was almost dark. I did not notice any skipping of spark however I was more interested in what was in front of me at the time.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Sorry.. as far as spark plug color they are all the same and clean but always come out wet. Also I forgot to mention that sometimes the carbs are spitting fuel out which seemed odd to me and pointed me toward the reeds. I'm hoping it's not the reeds however if it is where can new ones be purchased?

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

It is almost never the reeds. Carb Spitting is not good, however. Idle pickup timing should be 4-6*BTDC. This is when the carbs are just about to open and has nothing to do with timing at idle speed. There is a brass plate on the distributor that must be turned to set this timing. With the timing light on spark plug 1, and the rest of the spark plugs removed. Ign on, crank the motor and observe timing, while advancing throttle. When timing reaches 4-6* BTDC, leave throttle at that spot. Now loosen two bolts holding the plate on the distributor body that has the "fingers" that open the carbs, with a 5/16" wrench. Adjust the plate until it touches the carb lever, and tighten bolts. Now she is synched.....

 

[DAN M VAGOS]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Have you tryed a good spark tester and put it unser a load. I had a merk that ran great but onse in gear just had no power and on mine it was bad coils that gust could not produce a good spark under a load.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Thank you Chris and Dan.
Chris... I hope your right about the reeds however I red elsewhere in this forum just a couple hours ago someone with very similar issues and found a split in their reed that runs 5 and 6. They did however have an issue with compression which I do not or at least do not seem to. I'll let the marina know however I think they are adjusting it to book spec. Thank you.
Dan...no I have not and it sounds feasible however they marina stated they checked the spark and all was good. I'll ask them if they were able to check it under load.
Thanks again everyone... any more ideas? What else could cause it to spit gas out of the carbs?

 

[mr 88]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

After following Chris's excellent advice I would check the vacuum line that runs to the bottom of the fuel pump,check for leaks or crimps.Not sure if the brass plate that Chris is talking about is the one with the "tab" near the top of the distributor. There is a adjustment bolt that uses a 1/2" locking nut. That is accessed with the top-hat off. That gap between the end of the bolt and the tab also has a bearing on your ability to accelerate.That may be adjusted in or out,try that if all else fails,gap is normally around 1/4".When making these adjustments do one and only one thing at a time,then test.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Thanks to all for the advice. Does anyone have any reason why the carbs would be spitting gas other than reeds?

 

[canoemang]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Bad needles and seats or floats not properly adjusted would cause gas to come out of the throat of the carb.

saw the marina adjusted the floats but still..

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Yes I removed, cleaned and adjusted the carbs including the float settings. The marina said they attempted the same thing but they were ok and didn't need adjusted. I'm not sure if they replaced the needles and seats. I did not and they mentioned doing that in hopes to solve the spitting issue but I do know after the put the carbs back on it still spit however I do not know if they replaced the needles and seats.
I'll ask them here shortly when I take all this info to them.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

OK... here is the latest. Word from Marina is they tried all these suggestions and then some however their position is the motor must just be "too tired" and needs rebuilt. Does ANYONE concur with this? I'm going to pick the boat up from the marina shortly and see if they gouge me or not on this. I hope not as I'm unemployed but trying to make this a usable boat. Regardless does anyone have a direction for me to go? If not my plan will be to tinker with it a little myself again and if I have no good luck then pull the power head and check the lower shaft seal. If that is good go to the REEDs which will mean pretty much rebuild it. When I checked compression I got about 110 on each cylinder they stated they showed 125 per cylinder. That could be as my gage is pretty old however at these numbers would any reputable shop state it must just be "too tired"? I'm looking for anything left to try...

Thank you all for the help and suggestions!

 

[bgc]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Sorry.. as far as spark plug color they are all the same and clean but always come out wet. Also I forgot to mention that sometimes the carbs are spitting fuel out which seemed odd to me and pointed me toward the reeds. I'm hoping it's not the reeds however if it is where can new ones be purchased?

Clean like new? Or tan? Wet with water or fuel?

 

[Toddboat]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Sometimes compression numbers will be different depending on how you do the test. It should be done only once the motor has warmed up. Squirting some oil into the cylinders prior to the test can generate higher numbers because the oil seals the tiny space between the rings and the cylinder walls. The fact that you got a different reading than the marina is not important. What's important is that all cylinders test about the same. It seems you not only have good compression, but you also have a fairly healthy motor. If a motor has good compression, then the major rebuild components are eliminated from the equation (the block, cylinders, pistons, crankshaft, head gasket, etc). Everything else, including reeds, are an easy fix.
You obviously have a carb problem, which could give you the symptoms you describe. I just cleaned my carbs very thoroughly and thought they were surgically clean. But my motor would still run rough and stall at idle. Next I removed all plastic and rubber parts of the carbs and soaked the carbs in carb cleaner for a couple days. I was surprised by how many little specks of debris were in the bottom of the container after doing this. So much for my surgical cleaning!
The tiny passages in the carbs may not be entirely blocked, but could be restricted, like an artery would be.
The bath cleans this out. After you remove the carbs from the bath, then you do the following, and very precisely follow these steps...
Follow all of the circuitry in the carbs until you fully understand how the fuel flows through every part of the carb. Find the idle circuit, the low speed circuit and the high speed jet. Shoot water or air through all orifices until you completely understand how the fuel flows. You can do this in part by covering the high speed jet while shooting water through it to find how fuel makes it's way to the low speed jet, etc. Once you fully understand the circuitry in the carbs, then use spray carb cleaner to focus on those very areas that are vital to fuel flow. Clean them out 100%. Then reassemble the carbs and test the needle valve. You do this by blowing air into the fuel inlet. You can just use your mouth for this. With the carb right side up, air should blow right through. With the carb upside down, no air should blow through. If it does, then play around with the needle/seat/float until you get it to seal properly. If you cannot achieve a perfect seal, you will have to buy new needle & seat and possibly a new float or two (depending on how many carbs are faulty). These old outboards had cork floats which were finished with shellac I believe. That worked fine with no ethanol, but today the ethanol eats away the shellac making the float more like a sponge. New floats (plastic ones if you can get them) would probably be a worthy investment. While you're in the carbs, replace any iffy gaskets. An air leak can cause poor performance.
Now with the carbs reassembled, you are only approximately 12 bolts away from accessing the reeds. Remove the manifold behind the carbs. The reed assembly will pull out and the individual reed assemblies can be removed. Clean them if they are sticky. Replace anything that is damaged. When reassembling the reed assembly, make sure to torque the bolts per specs, tightening all bolts equally, little by little as you work your way around. This connection must not leak air, so a healthy gasket and proper reassembly is a must.
I think after you do this, you may have solved your problem. If not, then at least you've learned a lot about carb circuitry and have overcome your fear of accessing the reeds.

 

[bgc]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Sometimes compression numbers will be different depending on how you do the test. It should be done only once the motor has warmed up. Squirting some oil into the cylinders prior to the test can generate higher numbers because the oil seals the tiny space between the rings and the cylinder walls. The fact that you got a different reading than the marina is not important. What's important is that all cylinders test about the same. It seems you not only have good compression, but you also have a fairly healthy motor. If a motor has good compression, then the major rebuild components are eliminated from the equation (the block, cylinders, pistons, crankshaft, head gasket, etc). Everything else, including reeds, are an easy fix.
You obviously have a carb problem, which could give you the symptoms you describe. I just cleaned my carbs very thoroughly and thought they were surgically clean. But my motor would still run rough and stall at idle. Next I removed all plastic and rubber parts of the carbs and soaked the carbs in carb cleaner for a couple days. I was surprised by how many little specks of debris were in the bottom of the container after doing this. So much for my surgical cleaning!
The tiny passages in the carbs may not be entirely blocked, but could be restricted, like an artery would be.
The bath cleans this out. After you remove the carbs from the bath, then you do the following, and very precisely follow these steps...
Follow all of the circuitry in the carbs until you fully understand how the fuel flows through every part of the carb. Find the idle circuit, the low speed circuit and the high speed jet. Shoot water or air through all orifices until you completely understand how the fuel flows. You can do this in part by covering the high speed jet while shooting water through it to find how fuel makes it's way to the low speed jet, etc. Once you fully understand the circuitry in the carbs, then use spray carb cleaner to focus on those very areas that are vital to fuel flow. Clean them out 100%. Then reassemble the carbs and test the needle valve. You do this by blowing air into the fuel inlet. You can just use your mouth for this. With the carb right side up, air should blow right through. With the carb upside down, no air should blow through. If it does, then play around with the needle/seat/float until you get it to seal properly. If you cannot achieve a perfect seal, you will have to buy new needle & seat and possibly a new float or two (depending on how many carbs are faulty). These old outboards had cork floats which were finished with shellac I believe. That worked fine with no ethanol, but today the ethanol eats away the shellac making the float more like a sponge. New floats (plastic ones if you can get them) would probably be a worthy investment. While you're in the carbs, replace any iffy gaskets. An air leak can cause poor performance.
Now with the carbs reassembled, you are only approximately 12 bolts away from accessing the reeds. Remove the manifold behind the carbs. The reed assembly will pull out and the individual reed assemblies can be removed. Clean them if they are sticky. Replace anything that is damaged. When reassembling the reed assembly, make sure to torque the bolts per specs, tightening all bolts equally, little by little as you work your way around. This connection must not leak air, so a healthy gasket and proper reassembly is a must.
I think after you do this, you may have solved your problem. If not, then at least you've learned a lot about carb circuitry and have overcome your fear of accessing the reeds.

I missed this day in class and have been doing it wrong.

 

[mr 88]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

On my 78 Merc the reeds are located on the crank and the whole engine has to be torn apart to get to them. As stated previously,the reeds rarely go and after reading your post again I believe going after them is not going to be the answer.Have you checked/tested the switch box and coil ? Get the reeds out of your mind,your leaking fuel is in your carb set ups,NOT the reeds,you have some marina hacks that do not have a clue how to set up a Tower and they would rather see you buy a newer motor from them than be hassled with your issues.I would get that motor out of there hands as they are clueless. Did you adjust or locate the metal ring with the tab sticking down on the top of the distributor that I suggested you tinker with ????

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

BGC... Yes they look clean like new on only wet with fuel. The marina stated they did not see any water on them and I dont recall seeing any water on them.
ToddBoat... thank you for the information however other than soaking them for days I did as you mentioned. I traced every port and followed it from beginning to end to ensure they were open and flowing I not only ran a LOT of compressed carb cleaner through them I also blew them out with compressed air. I also made sure the rubber hose that is used for the backdraft system was replaced with new as 2 of them had split. The carbs were rebuilt a few years ago and have plastic floats. They may need needles and seats however everything else is in good shape and clean. I can look into soaking them however I cleaned them "thoroughly" and the marina stated they cleaned them and tried different float levels as well in attempts to make them work properly. I've also been told my reeds are mounted around the crankshaft as Mr 88 states his are on the 78. Looking in behind the carbs that seems to be the case. Are you sure after the carbs are off that removing 12 bolts the reeds will come out? if that is the case it's a no brainer to at least check/clean them.
Mr 88... I'm leaning towards reeds because there was another post in this forum with similar issues that ended up being a reed problem between cylinders 5/6 however if I'm not mistaken there was a compression difference there was well. But the key is he was spitting gas as well and once this was fixed those issues were solved and it ran as it should. I dont know how to test the switch box and coil under load. I did purchase a spark tester today which will only show that is has spark and is firing. Not sure what else to do there.

Also... when I picked it up today the marina told me they were informed by whoever they call when they cant figure these things out that it is most likely the labyrinth seals/rings. I've never heard of those. Could that be the case? if so they say I'll need a new block.

It only gets better. I'm almost to the point of disassembling the whole motor and parting it out. I got screwed bad on this deal as the boat is rotten as well.

 

[mr 88]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Yes the girl has a seal and to replace it means tearing it all the way down. You do not need a new block as the seal is available.You stated you had it running at 2500 and then some. To me your first post sounded like it was just a bit off so don't throw the towel in,sit back and rehash the whole thing.Did you check the fuel pump vacuum line ? Did you set it up like Chris suggested ? Your max timing with todays fuel should be closer to 19 [which has nothing to do with your issue] the next time your timing light is out.Your reeds are metal and in my opinion are not the cause of your fuel overflow.That carb has a seat and needle issue. How is your fuel line and primer bulb? Does it hard or bleed down? Go over the Link N Sync one more time.

 

[bgc]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Floats too high, lower seal going bad and yes, the reeds are in the block. My previous response was sarcasm.....I never missed a class

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

I'll work on it some more today. I have a jet ski to get done first. Thanks to all who responded. I'll post back what I find, if anything. I still need a good way to test spark under load and the switch box. Anyone?