Help 73model 1150 wiring

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spargs

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Hey guys, I am looking for some help from some experts (probably laddies or clams) on wiring on my 1150 merc tower of power. The model is from the 73 vintage and i have recently rebuilt the carbs on it. Stupidly I didn't take any photos on how the wires were originally layed out so it was pretty much redone from memory. Could someone please with some knowledge confirm or correct my layout, I have a manual but some of the colours are different. I am sure something must be wrong, because It's not running as well as it was and the tacho isn't displaying anything.<br /> <br />The wires I am talking about are in reference to the rectifier and the switchbox. When refering to which side, It is as if i am looking back at the motor from inside the boat.<br /><br />My current configuration on the right hand side (from bottom to top) on the switch box is, black, tan/olive, brown. The brown wire goes to some plastic thingy which i believe is the mercury switch. From this switch another brown wire comes out and I have absolutely no idea where this is meant to go??<br /><br />For the left hand side in reference to the rectifier (bottom to top) I have red, olive/tan, olive/tan.How do i know which olive/tan wire goes where?<br /><br />Between the rectifier and switchbox, there is a black wire which i have earthed to the cowling?<br /><br />Left hand side switchbox (bottom to top), I have, tan/olive pickybacked with brown, red, nothing (was like this before I bought the boat even though there is a nut for a wire) and then green.<br /><br />Thanks for your help guys, any info would be much appreciated as I am in dire straights right now!!!<br /><br />Cheers Nick
 
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Laddies

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Re: Help 73model 1150 wiring

Switch Box--port side--All dist. wires<br />top----blk<br />center-white<br />bottom-brown<br />Starboard side<br />top----green coil wire<br />2nd--brn tach.<br />3rd--red 12v hot all the time<br />bottom-white ign switch wire<br /><br />Rectifier <br />red--center or + terminal depends on the type of rect.<br />yellow- on the other 2 terminals and possably a grey or the old brown tach. wire from the empty term. on the starboard side of the switch box the are probaly the wire that look olive and come from the stator
 
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spargs

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Re: Help 73model 1150 wiring

Thanks Laddies, <br /><br />got the engine wiring all sorted out and was able to start her up :) . Was running pretty well in neutral but I found that the throttle cable was not opening up the carbs well at all. The fast idle lever was only allowing me to open the throttle up to approx 2000-2500 rpm??? <br /><br />So I pulled off the throttle cable and just controlled the cable via the throttle arm and was able to rev the girl up to 5000-5500 rpm! <br /><br />So one question, how to fix the throttle cable?<br /><br />2) when I put the motor in gear (in test tank) after idling from b/w 800-1000rpm the engine just dies, what do i do to fix this. I have just rebuilt the carbs and currently decarb is in process (soaking into the cylinders over night.) Any suggestions?<br /><br />Thanks<br /><br />Nick
 
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Laddies

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Re: Help 73model 1150 wiring

Nick, first most larger horsepower engines won't idle in gear in a test tank without a test wheel. A test tank won't displace enough water movement so the engine is loaded way to much. The control box problem really isn't a problem because it is design to work that way so someone doesn't overrev the engine on startup 2500 RPM is plenty for start and warm up -- Bob
 
Clams Canino

Clams Canino

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Re: Help 73model 1150 wiring

Ya, reving it much over 2000 or so with no load is real good way to blow it up.<br /><br />-W
 
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spargs

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Re: Help 73model 1150 wiring

Thanks guys,<br /><br />My concern is, I have only taken it out once previously and to say that it went well would be a major overstatement. <br /><br />When idling the engine died straight away when put in gear and the only way to get it into gear was to dramatically increase the revs with the fast idle lever and slam it into forward, not something i think the gearbox would have enjoyed much! ;) <br /><br />when in gear, i could get no power out of it and only was able to get it to rev to 2000 maybe 2500 rpm!<br /><br />this is what led me to do the carbs as well as decarb the engine. Any suggestions as to what is wrong. I am worried that this merc has the old merc disease?
 
timmathis

timmathis

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Re: Help 73model 1150 wiring

Have you done a compression check? Or set the timing?
 
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spargs

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Re: Help 73model 1150 wiring

The timing had APPARENTLY been set prior to taking it out but it wasn't by me. I haven't set the timing since I have adjusted the carbs, something I think I will do soon. I had someone look at it and he said that it is overfiring on cylinder 2. I dont know whether I have fixed that or not but I gave the distributer cap a good coat of CRC/WD40. I may end up needing to replace the ignition leads because they may be sparking each other. I am sure this will have contributed to the problem but I dont know how that this is fixed?<br /><br />In terms of compression when i bought the thing, compression was good in 5 out of the 6 cylinders. Compression was just outside the 10% range in cylinder number 3. That is why I have done a decarb on the engine, hopefully it will improve the compression on this cylinder.<br /><br />So that is what I'm working with, any other suggestions would be great.
 
timmathis

timmathis

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Re: Help 73model 1150 wiring

You need to change the plug wires and do a link & synk then you should be good to go. As long you don't have a fuel problem. Tim
 
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MercFan

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Re: Help 73model 1150 wiring

I'd also suspect fuel pumps.<br />Battled with my '70 1150 for months. Replaced the diaphrams twice. Finally it was the non-returns in the pumps that were either not sealing, or not closing fast enough at high rpm. Left them as is and bought a low pressure SU pump. <br /><br />Sorted me out fine
 
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spargs

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Re: Help 73model 1150 wiring

Well i took out the boat again and this time the motor went pretty well. I gave timed the motor according to clams post but still am yet to do the idle. Now I have a question re the performance of my boat...<br /><br />The hull is a 16 foot runabout, and at WOT the inline 6 was only reaching 60km/h (37 miles/h) and the RPM's were b/w 4800-5000. Should I not be getting a better speed than this? Do you think it is a prop issue?
 
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Laddies

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Re: Help 73model 1150 wiring

spargs, the RPM is a little low, I like to run the I/6 engines just under 6000. If you are running a prop with alot of blade area amd a couple inches to much pitch the engine will stall when shifted. Usally if the boat is moving the engine will keep on idleing but crappy if you have this problem
 
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MercFan

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Re: Help 73model 1150 wiring

Spargs,<br /><br />I'm running the exact same engine on a similar hull. What's your prop diameter and pitch?
 
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spargs

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Re: Help 73model 1150 wiring

Laddies, <br /><br />The manual i have says the max rpms should be between 5000-5500 rpm... Wouldn't 6000 kill it?<br /><br />Mercfan,<br /><br />I am not sure as to what pitch the prop is. What sort of speed do you get out of your boat/motor combo and what are your max rpms?<br /><br />Here is a link to a photo of my hull. Apparently they are quite heavy and the deep V doesn't help the top speed.<br /><br /> http://www.shareaproject.com/pages/imageDetail,p,171,i,2341,00.html <br /><br /> http://www.shareaproject.com/pages/imageDetail,p,171,i,2344,00.html
 
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MercFan

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Re: Help 73model 1150 wiring

Sprags,<br /><br />We're about the same on size, but your hull looks heavier than mine.<br /><br />I've been at 63km/h on my inboard speedo. Don't have a GPS. I'm a bit over propped, so my WOT rpm at that speed is 4850rpm.<br /><br />That's running a 17in. pitch and 13.75in diameter prop 3 blade Al. black max.<br /><br />The pitch you can read from your prop. The number ends in 15P or 17P or whatever.<br /><br />I don't know if you can get the diameter from there, but my prop just clears the cavitation plate by about 1/2in.
 
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Laddies

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Re: Help 73model 1150 wiring

spargs you are better off at 5800 to 6000 than 4800, it will live longer because it is not loaded as much and will cool better. That is if the engine is in good mechanical condition
 
Clams Canino

Clams Canino

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Re: Help 73model 1150 wiring

Spargs dood, he's saying to prop it to make near 6000, not to run it there all the time. :D <br /><br />I tend to prop the 115's to make at least 5500 and the 150's to make at least 5800<br /><br />The big inlines cruise nice at 4000-4300<br /><br />If I may rant, I don't know why people run a boat at WOT all the time when they'd never do it to a car. When I put a 15p SS on my boat to yank strange skier combo's the thing would turn 7k if you let it - I don't let it.<br /><br />-W
 
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