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

[Chris1956]

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

Gee, your compression is good. I see no reason to part it out.

 

[rriddle99]

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

Gee, your compression is good. I see no reason to part it out.

Well that would be great if it ran. Unfortunately I don't have the history with outboards to have the confidence some of you have. I'd love to have this boat running great unfortunately that is not the case and I've worked on it a lot and so has a marina and none of us including the help I've received on this forum has found the needle in the hay stack. As I said I'll try to work on it today and hopefully have better news later. If there was a specific procedure to follow to test the switch box, coil, stator, rectifier under load I'd love to see it

Regardless I thank you all for your advise.

 

[Faztbullet]

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

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.

They are on the reed blocks ..not engine.

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.

Forget what Toddboat posted as for a V-6 not a Inline and no manifold wont come off....

Gee, your compression is good. I see no reason to part it out.

It can have good compression and still be worn out as cylinder wear around ports from side thrust and ompression is just a indicator that cylinder/s can make combustion. At 110psi engine is tired as when new that motor had 145+psi compression due to hi-dome pistons.

 

[rriddle99]

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

It can have good compression and still be worn out as cylinder wear around ports from side thrust and ompression is just a indicator that cylinder/s can make combustion. At 110psi engine is tired as when new that motor had 145+psi compression due to hi-dome pistons.

When I ran ran the compression it was a cold engine and had not been run. I'll do it again after running it. Marina got 125 on all cylinders. You still consider that tired?

 

[Faztbullet]

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

Marina got 125 on all cylinders. You still consider that tired?

That minimum in my book for hi-dome engines.... also gauges read different. I use a Merc screw in tester that was calibrated in ANG hydraulic shop. Worn labyrinth seals on reed block will not cause spit back,they will cause idling problems and die when put in gear problems. Low compression that cannot overcome engine backpressure in water can cause some slight spit back but run great on a hose....

 

[rriddle99]

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

Ok... here is the latest update. I put boat on water and started it. Ran it with high idle momentarily and it was smooth so I backed it down to idle where it ran for a few seconds then slowed down and died. Would only restart with idle lever set to middle or full idle. I'm skipping all the main commentary and rolling to the reality... it will run and run very well on the water if you roll it into gear and hit half to 3/4 throttle right away... it then will take off and do plane out and run wide open or mid throttle or you can even slow it down to idle in gear however as soon as you go to neutral it will die. If you idle in gear for a period of time it will roll back to full throttle and run like a new engine however if you let it die you will have to start it with high idle, then pull idle down and roll it into gear and half or more throttle quickly while tapping the choke button. Once it "catches" it launches like a new engine and runs well. I'm not sure if my speedo is accurate but I saw about 54mph a couple times will still picking up speed. There was a few times I wondered if my engine was revving too high and it was wide open and running as good as I could ever hope and all works well as long as you done pull the throttle back too fast or bring it to neutral without pulling the fast idle up at the same time.

So all this being said it sounds like it's starving for fuel on the low to mid range throttle. As mentioned before I've cleaned the carbs and these carb still have fuel spitting out of them so it's hard for me to believe the floats are not set high enough and I can believe they are sticking because I could run it full throttle as long as I wanted to today. I cant list off the settings right now because we were caught in a rain storm and I did not get anything verified. It is right now as the marina left it and other than the idle I'd say it's set pretty well. Can anyone give me ideas to try next? I'm going to pick it up tomorrow and "tinker" some more probably focussing on the fuel system and idle timing.:joyous:

 

[mr 88]

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

What rpm are you idling at with the muffs vs in the water ? Have you checked the fuel pump vacuum line ? If you are spitting out fuel you still have a float/needle and seat issue. You may be flooding the engine and when advancing the throttle you are flooding it more before the ignition advances,once in a while you get past that point and off she goes,you slow down to neutral and flood it out again. Your idle may have to be turned up a 100 or so rpm. Then you may have to open the idle screws a blade width at a time to get your smooth acceleration after you have the spittin carb fixed.Sometimes it's hard to get these to idle real smooth and accelerate just as well,I let it lump a bit at slow idle but have excellent throttle response in return.....BTW Like I said the marina "mechanics" are clueless with these babies,stick to the forum if you want to save money and get it running correctly.

 

[rriddle99]

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

I will connect a tach tomorrow. I was without one and the marina used one during their set up process. I'll report all the specs tomorrow after I get it home and get the tach connected, etc. NO... I have not checked that line as yet but will tomorrow. I did find and issue with the coil wire right before I put it on the water so today I purchased a new wire set and will install those tomorrow as well.

And yes I understand the forum is a good way to gain an understanding without an investment of dollars only time. I sure do appreciate all the support I've seen on this issue and others I've posted. I'll post back tomorrow when I have the boat here and can state the specs I know everyone is interested in knowing are set correctly. I do know one thing.. based on how she ran today if I can get by this issue I'll have a motor well worth the investment thus far!:clap2:

 

[mr 88]

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

Car wires are not correct,must be merc specific. The wires screw into the distributor.

 

[bgc]

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

"So all this being said it sounds like it's starving for fuel on the low to mid range throttle. As mentioned before I've cleaned the carbs and these carb still have fuel spitting out of them so it's hard for me to believe the floats are not set high enough and I can believe they are sticking because I could run it full throttle as long as I wanted to today. I cant list off the settings right now because we were caught in a rain storm and I did not get anything verified. It is right now as the marina left it and other than the idle I'd say it's set pretty well. Can anyone give me ideas to try next? I'm going to pick it up tomorrow and "tinker" some more probably focussing on the fuel system and idle timing.:joyous:"

Check to see if they're set too high. Mercury includes a gauge for this in the carb kit.

If your seals are failing it will show up more at lower RPM's as the block is drawing air from around the crank. One of the tricks we use at the shop is to spray Choke and Carb Cleaner under the flywheel while shes running on the muffs for the upper. The lower seal you can pull the bleed hose off the port feeding it and squirt with two cycle oil into it to temporally seal it for testing.

 

[rriddle99]

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

It has car wires on it currently. They are not screwed in right now. That could be part of the issue. I'll pull the cap and see if that is part of the issue. I know the coil wire does not screw in as it has a crimped on connector like a car does.

 

[mr 88]

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

Plug wires should be solid core stainless steel and they screw into the distributor.Lose the car wires.

 

[rriddle99]

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

Plug wires should be solid core stainless steel and they screw into the distributor.Lose the car wires.

Help me understand why? I have some history in electricity and would like to understand the logic.

Also can anyone tell me how the floats should be set? I set them by the book and i know the marina changed them higher and lower in attempts to resolve the issue. Should they be set by the book? I know I had this problem when they were set by the book as well.

I apologize for not updating more. I ended up helping a friend then spent the rest of the day working on my 327 for my SeaRay. I plan on spending some time on it tomorrow for sure.

 

[mr 88]

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

Not sure of the exact reason why,I have read it more than a few times,maybe some one else will chime in,or do a search on here for similar threads on plug wires.You can also search the float level.Do not forget the needle and seat while you are in there as that is the probable cause.

 

[rriddle99]

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

OK.. here's my latest update. I found the coil trigger wire was practically off so I fixed that. I also replaced the coil wire to the distributor and all the plug wires with stranded core non resistive wires. I did not screw them in I just pressed them in and used 90* covers to help hold them. It may sound like back yard mechanic but it works quite well. I tested my idle rpm on muffs but did not have the tach installed while on water so I cannot speak to that scenario however it was idling at 1000rpm on muffs. I took it to the lake and warmed as I was warming it up it acted similar to before. I adjusted the min idle screw a little (if I had to guess It's probably around 1k idle in water now) and after running it around the lake for about an hour I was able to get it to go down to idle and reverse and back in forward if I moved it engaged it then and slowly without stopping give it more throttle.

The odd part is it runs much better going into reverse than it does forward. It doesn't seem to try to die as quickly going into reverse and it smoother than forward (as far as running). It's like it's tuned differently. Not knowing any better now it seems like idle mixture may solve the problem but I wont know until I get it out there with a procedure to follow. Today I was just making sure it was working with new wires,etc.

I did check the vacuum lines going into the fuel pump and they are in tact and seem to be ok. While I was running it on the muffs I put my hand over the carbs one at a time to feel the draw and see how they reacted. They all would draw the engine down with it trying to die pretty quick on the top carb and the slowest on the bottom. Also the top carb had more draw than the middle and a lot more draw than the lower carb. They would all spit gas out as I covered them up.

Tomorrow I'm going to install a tack and a volt gage then tidy up more of the wiring to make sure that is not any of the issue. What other suggestions based on these updates?

 

[rriddle99]

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

I found the marina had left the top carb at 3 1/4 turns, middle carb at 2 turns and the bottom carb at 1 3/4 turns out. Does that make sense? Also the carbs leaked a lot of gas out when I tilted the motor up today after running it on the muffs. I'm spending most of today on wiring and getting boat ready to use. I'm lookikng for controls and waring harness for this motor. I'd like good used ones but I'll buy new if I can find the right price.

 

[mr 88]

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

You will lose gas out the carbs when you tilt it up,that's why there is a plastic tray underneath the carbs that has a hose attached to it which dumps the gas into the water. The only way to stop it is to pull the fuel line from the engine and run her dry.Your base for all 3 carbs should be 1 1/2 turns out. Put her in gear while in the water to fine tune the carbs,can't be done on muffs,no back pressure.Now after you have it idling decently the tricky part comes in.In most cases after you have adjusted the idle screws the beast will not accelerate do to the carb design. If she does not want to accelerate,more than likely, you open up the idle jets one at a time [ the width of your screwdriver blade ],starting with the top, eventually you will find a happy medium.NEVER go back to that hack place for work on your Tower.

 

[rriddle99]

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

I will lose gas regardless of float setting? That seems like such a waste. I thought if I set the floats lower it would solve this problem... ? Anyway the weather says rain all day tomorrow. If its not too bad I'll still put it in the water and adjust the idle screws. I spent today getting some wiring fixed on the motor and wired up a tach and voltmeter just to help gage what she's doing on the water.

What about the 3 carbs having different draw velocities at the throat? The lower carb seems dramatically different than the other 2 and the top has the most draw of them all. I guess I didnt look to see if the marina hand them opening up at the same time... shame on me.

How do you suggest I set the car synch between each other? I had been setting it so they would all open very close to the same time. Is that the correct way and will that stop them from going to full by having the linkage bind?

Any thoughts would be appreciated. Thank you!

 

[mr 88]

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

The bowl is full of gas from when you ran it at a straight up and down.Now when you tilt it up,the gas that was sitting level is now pushed out by gravity.After the bowl emptys the needle and seat if working correctly stops the fuel flow.The floats-levels in this case have nothing do do with your spillage and if that bothers you then do as I suggested before,pull the gas line at the motor and let it stall out.Set everything so the three work in complete unison.Not sure of why the different draw if your compression is fairly close on all 6.I have never even checked mine for that,might be the same as yours for all I know, but it runs like a bat out of hell. So I would not worry about that if I got her doing what you want it to do,speed wise.

 

[kungpaoshizi]

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

I recently had somewhat the same issue with mine, it turned out to be the 4 year old battery had a short and could not keep up with the current draw unless the stator was up to speed producing X amps to the circuit. Even though the battery tested good at walmart and autozone, I figured why not, replaced it, now I can idle down to 500 rpms just fine.