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

[rriddle99]

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

I have it running much better and will post all relevant info about the how's and whys of what I found as soon as i have it put together. Now the main problem is it doesn't run as well and doesn't like to start with the covers on. I realize that means its rich however why would the covers make that much difference. I did remove the baffle from the upper cowl which helped but not enough. Thoughts???

 

[rriddle99]

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

Sorry it's taken me so long to update. I actually have it running good enough to use it some and have done some fishing as well as working on a couple pontoons for my neighbors. Anyway... here is where it stands now:

I've replaced ALL engine and control related wiring. New harnesses for interior and exterior. Ignition wires including all to and from the control box. I'm not able to get a tach signal from the control box but I do when I connect it to the stator. After I recieved it back from the marina it did run some what better than when I took it to them however they had the carbs set so the lower carb would barely open at WOT and they had changed the timing from where I had it set by the book. I also noticed that they had moved the timing pointer back to a position that was scribed on the alignment pin instead of actually bein on TDC. When I had taken it to them I had set the pointer via the dial indicated .464 prior to tdc as described in the manual. That put the pointer off to one side but still within the adjustment limit. Regardless after I received it backk from the marina I checked it all again with TDC and not the the dial indicator method. I ended up moving the distribnutor one tooth on the belt. I knew the distributor arrow was just a little off before however it was similar to some pics I had seen on these forum postings so I figured I was ok. Unfortunately here is my timing points:
idle - 4*
High idle - 8*
idle in gear 4*
Max timing - 28*

with these settings it starts hard and when I put it in gear I HAVE to give it some throttle or it will die. All carbs are 2.5 turns out on idle which works best for how it's set up so far. Typically when I hammer on it... it goes. Idle in water is about 800-1000rpm (sometimes up to 1200) in gear anywhere from 500 to 800 if it doesnt try to die. If I have it in gear and run it around 1000rpm it sounds like it's missing and the motor shakes a lot and smokes a lot however it never changes speed and seems to be ok running that way all day. Most of the time if I ram it to WOT it takes off however when it does the engine seem to speed up in stages and once its on plane it really pushes you back in the seat and the RPM rises very quickly. Not sure what the max rpm range of this motor is supposed to be however i'm getting about 5000 rpm at WOT and up to 5200 if i push the max trim on the motor.
Also I can make it run pretty well and not want to die transitioning between idle ouy of gear and in (for the most part) however I cant find that sweet spot with the motor cover on. It seems like it's starving for air with them on. I removed the baffle out of the hand hold area on top engine cover and that helped however it still performs noticably different with the covers on and is more difficult to tune. I have new needles and seats that I plan to put in sometime this week and at tha point I will adjust the floats if necessary. Do you folks suggest I set them by the book or something different? I seem to push a lot of fuel out of the carbs especially when I tilt the motor. Even without tilting the motor the fuel will leak through the butterfly shaft down to the next carb or into the water if it's the bottom carb.

I did find a quick and easy video to help set up the timing points out of the water however it didnt work for me as I had to adjust mine to tune it in quite a bit. Here is thge link: How to Link and Sync Mercury 1150 Inline 6 - YouTube

I need to get this motor to where it will idle decently and transition from neutral to forward and reverse without it dying on me and not beating up my gearbox. I'm more worried about that than top end at least right now. Can anyone tell me what this motor's effective rpm range is supposed to be? Not that it matters a lot but I'm running 40:1 mixture right now just to make sure I dont burn it up.

I'm not sure if I missed anything but any help will be appreciated. I already apprecaite everyone's feedback up to this point. The good thing is I know the motor is not bad because there have been moments where is is VERY impressive with its accelleration however I cant seem to find the best of all worlds with it.

 

[mr 88]

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

You can run them up to 6+ grand all day long,they do not like to be lugged. When you moved it one tooth over you may have gone the wrong way,as the manual was written incorrectly according to my sources,[ it happened to me and we went the other way after learning of the mis-print ] ,so you may want to try that and reset your timing. 19 degrees with todays fuel or risk a burnt piston.

 

[rriddle99]

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

IF the manual was written incorrectly what is the correct way to set TDC on these? I was using a steel rule in the #1 cylinder to find TDC on the piston and equate that to the TDC mark on the flywheel. (after I had used the dial indicator method then having the marina change it)

 

[Chris1956]

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

Riddle, You must set the timing correctly. There are only two timing settings: Idle pickup and max spark advance. Anything else is meaningless. Use a screwdriver to set the top piston to top dead center. Now stick the ruler into the plug hole and measure to top of piston. Note reading. Add .464 inches to your measurement. Now turn flywheel CCW 1/4 turn. Now find the sume of the .464 and your measurement on the ruler. Stick that into the plug hole and turn flywheel CW until it hits ruler. Adjust timing pointer to read .464. Now turn flywheel to indicate TDC. Distributor pully arrow should point at punch mark on flywheel.

Reinstall sparkplug #1. Remove rest of plugs and stick them into their wires and ground their bases. Put timing light onto #1 plug wire. Remove prop. With motor in forward, use jumper wire on starter solenoid to activate starter. Advance throttle until timing reads 4-6* BTDC. Now without moving throttle, look to see if carbs are open or closed. Carbs are supposed to be closed, but ready to open, immediately upon advancing throttle. If not, adjust brass collar on distributor body (loosen two 5/16" stainless bolt heads to adjust.) After adjustment, tighten bolts.

Now advance throttle all the way. Crank motor and adjust throttle to show 21* BTDC timing. Adjust max spark advance screw (above distributor on plate), to stop the advance at that point.

Now adjust idle speed in water, motor warm to 900RPM, and tighten idle stop screw. Adjust throttle stop screw to keep carbs from hitting their stops at WOT.

That's it.

 

[rriddle99]

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

OK.. I followed your advice Chris (for the most part as Its not on the water yet) However I dont feel it's going to work. I had the timing set up correctly relative to .464/ TDC, pointer on distributor, etc. Now I have it set up to 5* and first throttle pickup and 0* at idle (for now) and about 20-21* at max advance. I can guarantee you this motor will not plane or take forever to plane at this max timing but I'll try it to see if there was something I missed before.

Also here are my plugs. I'm a little concerned about number 1 and number 6 cylinders:
View attachment 207577

Top left is cylinder 1 and bottom right is cylinder 6. Thoughts on if there is a problem I need to address.

I'll take it to the water and see how it performs and what if anything needs adjusted and report back.

However no one has commented on the fact that it runs dramatically different with the covers on that when they are off. Is this typical for this engine? Any help here would be appreciated as I'm trying to determine if I should get it more air to help dial it in.

Thanks!!

 

[rriddle99]

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

I meant 5* at first throttle pickup and 0* at idle

Also I forgot to mention that with all the plugs out if I turn the flywheel with the key on I can hear the arc (spark) inside the distributor at each wire location. Should it be sparking inside the distributor with no load on the end of the wire? I'd think it would be an open and no spark. That's confusing to me. Anyway with all spark plugs plugged into the wires and grounded outside of the block I can turn the flywheel and get each one to spark individually so there is no cross-firing going on that i can report.

Thank again to everyone for your help!

 

[Chris1956]

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

I was unable to see the spark plugs for some reason. Repost the picture.

The .464 setting is used to choose a single degree as Top Dead Center. If you think about it, the #1 piston is at TDC for multiple degrees of travel of the crank, as it stops rising, stays at TDC, and then starts to decend. Setting the TDC pointer to the .464" mark, when the piston is exactly down .464" eliminates that timing error.

So the timing is 5*BTDC when the carbs start to open, right? That is perfect, and the way the factory specifies. If you think you can design a better timing setting, I am not sure I can assist you.

 

[rriddle99]

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



Chris... here is the pic. Also please understand I'm not trying to reinvent the wheel here I only want the motor to run and not give me grief when loading and unloading it which is the problem I have. So please do not accuse me of wasting anyones time or being unproductive I'm only telling you what I have and what it does. I truly appreciate EVERYONE's help here and I do respect your wisdom. Please respect the fact that I'm trying to do the best with what I have and i'm not only getting information from you but others as well and not all the information is the same.

 

[rriddle99]

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

So... the boat is on the water and as I expected I could not even achieve 2K rpm at WOT. I have everything set as instructed however now that it's in the water I had to adjust the idle to achieve 900rpms. Which as soon as I put it in gear it will die unless I can get some throttle to it. I can back off the throttle quickly once it starts to rev up but if I don't do this it will die for sure. This is both forward and reverse this happens however it does still run smoother in reverse.

So I start across the water and as I said I cannot get 2k rpm out of it. so I stop, remove the covers and turn the max advance screw out about 1 full turn. Fire it back up and sure enough I punch it and it goes. Not like the monster it has before but it does stand up and get on plane pretty quickly. So I back it down and do it again a couple times and get the same result. Put the covers back on and cannot get to plane again. So I take off the covers and turn the max idle screw out about 1.5 turns and put covers back on. This time it takes off and does not achieve plane as quickly as it did without the covers on but it does and I take it across the lake. Full throttle only gets me 4900 rpm at this point. So I have to come down to idle speed to reach my area of the lake. it's about a 3-5 minute trek at about 1200 rpm to get there and once I do I nail it and again I cannot get it to achieve even 2k rpm so I let off and punch it over and over and same thing so I punch it again and turn the left and it launches. Its almost like a nitrous boost. So I let off and try it staight again and it luggs again then turn to left and away we go!

I had a 1988 cobra bass and ski with a 150 hp force (boat anchor) and I would turn when I was pulling someone on a tube and it did not have the power to get on plane with them behind it. So this makes me wonder about the prop. Now this prop has ran the boat well and launched pretty good so I assumed it was ok and there was once when the tach was not working that I achieved a lot more speed than I do now and the motor sounded like it was screaming. But ever since I've set it up close to what it's supposed to be ive never seen over 5400rpm and thats with the motor trimmed dangerously high.

It's a 19pitch prop. The numbers are "48 72762A4 19P" if anyone knows what that means. It is a stainless prop as well. The boat is about an 18ft 1978 Tennesee Valley charger with a Max gross weight of 2200 lbs.

Once I get done "tweaking it" and pull it from the water I'll be able to check the max timing point. I do have the first timing event at 5* and it is at the first pickup of the carb lever. The max event is at the 2nd pickup of the carb lever and I do have the throttle stop set to just shy of the carb stop.

The only way I've ever been successful at keeping it from dying on the low side was if it was idling around 1200 rpm or just shy of that between 1000 and 1200.

 

[Chris1956]

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

A 19"P prop may be a bit tall for that boat. If that is the case, the motor may not do better than idle. Can you try a 17"P or 15"P prop?

Advancing the max timing past 21*BTDC will allow you to damage your motor. Your carb idle mixture may be a bit lean, causing your acceleration problems. Richen top carb 1/8 turn and see if that helps. Follow up with mid carb 1/8 turn enrichenment, and then bottom carb enrichment, testing after each adjustment.

 

[rriddle99]

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

I'm sorry Chris... I mis-spoke... it's not 2200lbs but 1200lbs. Do you still feel the prop to be a problem?

Also I reposted the pic of the plugs. Any comment on those? What about the fact the covers make such a difference in operation of the motor? Is that normal? Like I said I'm running without the removable baffle in the top cover. Why would that be necessary?

Thank you!:happy:

 

[Chris1956]

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

The prop could still be an issue. I had that motor on a 16' speedboat. With a 21P prop, I could pull 2 skiiers out of the water. With a 23" P prop, and 1 skiier, it would not get above idle speed. The prop pitch must be low enough to develop enough RPM to have enough power to progress to faster RPM. The motor develops most of it's power in the mid-range of RPM.

The plugs looked OK to me. A bit dirty, but fine. Wipe them off and reinstall. Check for arcing from the plug wires to ground. Especially on the lower cylinders.

 

[rriddle99]

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

I'll look into a different prop as adding even 1 body does make a noticeable difference. Thanks for the feedback on the plugs. All wiring is new and I did have the plugs out and made sure while rotating the motor by hand only one sparked at a time and the spark seemed to be of equal intensity (visually) on all. The only thing that concerned me is I could hear the spark from the rotor to the cap connection points while I rotated the motor with only the #1 plug installed and all other wires empty. It would spark inside the cap on all connections. That seemed odd to me as I would have expected it to be "Open". As mentioned all plug wires are new and they are NOT arcing as I've determined this by the suggested on in this post (by hand and visually at night).

Any thoughts on the air restriction of having the covers installed?

 

[Chris1956]

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

Well, the ignition is very high voltage. If there is no path thru the spark plugs to ground, it may find another route.

The covers shoud not be restricting air. Maybe you have a leaking powerhead base gasket allowing exhaust back to the carbs? That will deprive the motor of oxygen, causing it to lose power.

 

[rriddle99]

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

That's logical. Is there a good way to test the upper and lower shaft seal as well as the powerhead base gasket? Or is the base gasket the lower shaft seal?

Also... I tuned it more yesterday and got it running pretty good. I also found I had water in the gas so that wasnt helping. Regardless I'll post my final settings from yesterday's adjustments but today I took it to the lake and it ran great all day. Other than some idle/starting issues that were minimal compared to what it had been. If it continues to run as it is I'll be happy. I was seeing 5300rpm easily and hole shots were spot on even with the covers on. I know as it stands now I'm probably around 29-30* btdc. I'm guessing that a I had set it to about 21* then put it on lake and could not plane out and tweaked carbs and max advance to tune it to where it is. I advanced it pretty far (seemingly) from where I started. I'll post tomorrow after I check it but I enjoyed all day of fishing today and will again tomorrow.

 

[jimmbo]

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

Could you post some pics of the engine? I ask this as I wonder if it is a 150. You have said it won't run unless the timing is advanced quite a bit more than spec. 29-30 BTDC is more like what the powerdome engines were speced at. The 150 was a Direct Charge design which used 19-20 BTDC as max advance.

 

[rriddle99]

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

current settings are as follows:

idle timing 4*
1st event 6*
max advance 28-29*
Top idle mixture 2 and 1/8 turns out
middle is 2 turns out
bottom is about 1 and 7/8 turns out
I'm trying to transfer pics now

There is always a strong gas or burnt fuel odor around the motor. Is that normal?

 

[rriddle99]

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

Also I'm not hearing any noises in the motor that would give me any indication that the max idle is a concern except it acts like it wants more. With this setting you can feel it like crazy when it hits plane and it get's to speed quick. I think I'll give it even more soon and see how it acts. It's real smooth at 4000rpm at the current setting and the throttle is very responsive.

Pics are too large so I have to shrink them to post. Will soon.

 

[rriddle99]

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