1977 Merc 1150 Power Loss

[imported_brian_w]

I have a 1977 Merc 1150, it starts good idles good<br />runs goods at low rpms in drive, but...when i open the throtle it bogs down like and loses all power like its idling, but i can hear it trying to get up to full speed. But the weird thing is that half the time it will run fine with WOT but it fluxuates alot. Sorry i dont have a tach. Also i noticed that the 3rd carb is leaking gas<br />and it pours out when you pump the primer ball.<br /><br />Here is what I have done. I started at the gas pump. I run premium gas <br />new gas tanks properly vented<br />new gas line and connectors<br />new gaskets and diaphram (sp)at fuel pump<br />new plugs<br />sprayed down carbs and jets with Carb cleaner with<br />carbs on powerhead.<br /><br />I am new to working on OB's and would appreciate any help. But i do have a manual!!<br /><br />Brian

 

[stocky]

Re: 1977 Merc 1150 Power Loss

Sounds like you have dirty carbs. Carb cleaner sprayed down the venturis will only clean the throat and butterflies. You should not use carb cleaner while engine is going. You will need to pull the cabies down and use the carb cleaner on the jets and needle and seat

 

[Gold Bear]

Re: 1977 Merc 1150 Power Loss

brian_w <br /> <br />After you follows stocky's advice.....<br /><br />1) Get a service manual.<br /><br />2) Set the idle mixture screws to two turns open measured from lightly seated.<br /><br />3) Using the service manual, perform timing and sync adjustment.<br /><br />4) The float setting on the 3rd carb is set to high. Use the manual to set the float level. (It shows you how to bend the float lever to adjust the level of the float.)<br /><br />This should take care of your problem.<br /><br />Good Luck, Gold Bear

 

[sho305]

Re: 1977 Merc 1150 Power Loss

I think you have different carbs than my '73 150, but I can remove the plugs/jets and spray through every passage on mine while on the motor. Figured that out after removing them, duh. Floats/filters on carbs still hard to get at but possible.<br /><br />Sounds like the carb/filter clean ought to fix you up good. Do not run much like that as those cylinders will get dry of oil if you have no oil injection.

 

[amtsst]

Re: 1977 Merc 1150 Power Loss

This is Deja Vu. My brother has a 1980 90hp merc inline-6. Thats exactly the same motor you have with a few tweaks.<br /><br />Well he had the same problem. Runs like a champion for a while and then winds down to half throttle and boggs there. We messed with it for a whle and then took it to the mechanic. Our local outboard monkey (private guy..works in his barn on weekends) fiddled with it and said, "powerpack". Well my little bro bought a 1977 1150 with a blown powerhead for parts. We yanked the powerpack off of the parts motor and put it on the 90. It worked perfectly for 10 minutes and then bogged down and started that same nonsense you're describing. We went back to the mechanic and he said, you've blown this second powerpack. <br /><br />Well something didn't sit right with me so we just took the boat home again. His solution was spend $1000 and replace the entire ignition system...on a 22 year old motor. I said, HECK NO!!!<br /><br />Well, I got to messing with it and discovered some frayed wiring coming out from under the flywheel. (Wires from the stator). I jiggled them around and the thing fired right back up to WOT and sounded perfect. After running for 20 minutes, it wound right back down to its old problem. Bogging and sounding like its lugging.<br /><br />Here is my theory. Old Mercs are famous for frayed wiring. Merc used cheap cables and the insulation comes right off after about 10-15 years. The proof is that with some jiggling, I can "fix" the problem. My next move will be to pull the flywheel and prove this theory but I just haven't gotten around to it yet since season is almost over and I just run my bigger boat rather than waste a Saturday fixing the merc. I figure that one of the wires that provides juice when the timing advances is frayed and shorting against the block. When you hit a certain throttle position, the timing advances and that wire is the bad one. I can run up to 1/2 throttle but no further... <br /><br />You described our problem perfectly. If you're going to get into it this season, PLEASE, PLEASE, PLEASE let me know by email if you get it figured out. amtsst@yahoo.com

 

[imported_brian_w]

Re: 1977 Merc 1150 Power Loss

Thanks for all the responses.<br />I just got home after taking the carbs off the <br />PH. And i got 3 complete carb rebuild kits. I am off to work on them! <br /><br />Brian

 

[imported_brian_w]

Re: 1977 Merc 1150 Power Loss

Well I have bad news... All the screws and caps have loctite on them and i cannot get them loose. The heads are just stripping. Any ideas??<br /><br />Thanks,<br />Brian

 

[sho305]

Re: 1977 Merc 1150 Power Loss

Loctite? You must be kidding. I have heard of the factory painting things for warranty but glue? Not good. Need to get it apart without trashing it.<br /><br />Also have heard of some Mercs having a high and a low speed alternator. When one goes out it does not charge at high/or low rpm and it runs funny at that speed due to low voltage to ignition! My old '73 just charges like crazy all the time and trashes the battery. I got 16 volts at 4000 rpm, and run 5400@WOT. 12.8v at idle with a new rectifier. I thinks that is why they changed them.

 

[imported_brian_w]

Re: 1977 Merc 1150 Power Loss

Well boys I got lucky today.... or lied to. The mechanic that sold me my outboard said that my 115 is the same as the 140, and it just so happened that he had a 140 in the back that blew up. So at no charge I got new carbs and some horses. Especially since while i was rebuilding my carbs my manual said to remove all the jets and tubes, but they were in so long i sucessfully managed to strip out a few items!<br /><br />But to no avail that did not fix my problem. (I still have to sync the carbs and check timing) It almost seems that the throttle is not wide open, like it has more throttle left. I will investigate tomorrow.<br /><br />Brian

 

[Jumper]

Re: 1977 Merc 1150 Power Loss

sho305<br />I've got a 73 Merc 850 and I was wondering if you could shed some light on what yours is doing. My email is Af1jumper@msn.com. Is this a common occurence with Merc from then?