84 Mercury 115HP stalls out while advancing throttle

[Molenite]

Alright I have one for you guys. I had a 1973 mercury 135 2 cycle ob. K runs perfect out of the water with the muffs on. Can go thru full cycles everything. As soon as I put it in the lake and throttle it up it bogs down and stalls out. Then I bought a 1984 Mercury 115 hp 2 cycle, I was all excited it starts great sounds better has more compression in the cylinders and now it is doing the exact same things. When at lake bogs down and dies out but will run fine out of the water. Already changed the power box or whatever its called. I need help ...... The only things the motor has in common is the fuel tank and the throttle cables. Can the throttle cables do this at all?

 

[arsenalpsu]

Re: 84 Mercury 115HP stalls out while advancing throttle

classic symptom of not firing on all cylinders. Either from fuel, compression, or no spark, and 75% of the time it's from not having spark. It sounds OK to the untrained ear out of the water b/c there is no load on the engine and it can rev up. BUT once you put a load on her missing a cylinder or two makes a huge difference. I'd bet your stator or a switchbox is bad in the 115hp I-6 (great motor by the way) Test for spark, get an OEM manual and get reading- you'll save a ton of money and have fun learning as you go.

 

[ClassyGlassy]

Re: 84 Mercury 115HP stalls out while advancing throttle

though arsenal brings up some good points, you're probably dealing with carb issues. Try turning your air/fuel mixture screws counter-clockwise, left, 1/4 turn on each carb then try the hole shot. Keep going 1/4 turn at a time until it takes off. This is a common issue especially if they've sat for a while. You should also look into rebuilding your carbs and doing a Link and Sync on the system as well. This just makes sure your timing and advance is synchronized with the throttle. Then the carb tuning ties it all together.

 

[arsenalpsu]

Re: 84 Mercury 115HP stalls out while advancing throttle

I think i may have been reading his problem wrong.... I was thinking it bogged down all the time, even with a slow acceleration and would not plane. IF he's talking about not getting a hole shot that you're correct, he's mostly likely runner her too lean.

Try a slow acceleration, when you hit WOT if your still, lets say at 2000-3500 RPM than you're missing spark on a few cylinders. IF you can get her up to +/- 5500 RMP with a slow hole shot than it's definitely your carbs- do a linc and sync.

Do that test and report back!

 

[Molenite]

Re: 84 Mercury 115HP stalls out while advancing throttle

k well update
So I have changed out the power packs checked spark, have good spark. Checked compression. All have around 120 psi +/- 3 or so. need to check fuel thanks guys will update

 

[johnbrabant]

Re: 84 Mercury 115HP stalls out while advancing throttle

What did the powerpacks cost you? I am thinking of just replacing all of the electronics on my 1986. Wish they sold a kit to replace the entire electronics system which would provide a savings by purchasing all items at once.

 

[asm_]

Re: 84 Mercury 115HP stalls out while advancing throttle

Any update?

I have the same motor with the same problem. Tuned the idle needle and got it to run at the lake, but the motor would bog at 1800RPM while under way, no matter how slow I bring up the throttle. I later found my carb #3 (cyl 5 & 6) is almost not sucking air. Spark checked, fuel is dripping out of the carb #3....

B

 

[arsenalpsu]

Re: 84 Mercury 115HP stalls out while advancing throttle

If you bog and don't accelerate at all check for spark, if you have good spark and compression then start looking at your fuel system. Replace the fuel diaphragm and do a lync and sync. If your acceleration hesitates but eventually takes off then you're running lean, you need to move each idle screw out 1/8 turn and try a hole shot. If it still does it keep moving them out until you can get a good hole shot. You could have dirty carbs but i think too many people lean that direction w/o checking everything thoroughly.

 

[partytymekaraoke]

Re: 84 Mercury 115HP stalls out while advancing throttle

Well you are in luck, I was going through this same problem. I did everything these guys said to do on here, but now i am starting to believe they not the people you should ask the question to. Since they don't think to tell you what the problem most likely is. I will make it short and sweet to you, My 1984 Mercury 115 hp was stalling at 1/4 throttle, i was told to do everything you will find in every forum on the www and noting worked. I called every master Mercury Mchanic who had 40 pluss years experience i was told to call. The next to last one i called told me i needed new reeds, hummm dont see how that would make it stall when it had none of the symptons of bad reeds. Then I emailed a guy who has a atricle on this forum about how to time your motor and adjust the carbs. I was getting ready to buy a new powerhead off him cause i was told i needed a complete overhaul to fix my supposingly bad reeds. He sent me back a email telling me to call him that a new power head would not fix my boat. He said to change my prop down to 20 pitch and it would fix my motor. so i did one better went down from a 14.5 X 23 pitch to a 13 X 19 pitch with this i gained 800 pluss RPM and my boat shot out of the hole and never looked back.. before i couldnt get but 1400 RPM before it would stall, now i am WOT 6200 rpm which is more than i want but i will throttle back to 5200 when i am running it.. The lession here is going down in pitch gives you around 200 more RPM's per inch. So my advice is check your prop pitch and go down to 19 at least. Then your boat will work awsome. Please let me and everyone else on here with this problem when you do this and it fixes your problem. I got my prop right here off this site for 85.00 much cheaper than 999.00 powerhead was going to be.

 

[asm_]

Re: 84 Mercury 115HP stalls out while advancing throttle

partytymekaraoke,

I'm sorry to poke a hole in your story. But, propping down only reduce the load on the motor. Assuming your motor used to ran on 14.5 X 23 prop, you haven't solve the problem, but only masked it.

In any case, thanks for sharing...

B

 

[partytymekaraoke]

Re: 84 Mercury 115HP stalls out while advancing throttle

No i solved my problem, i have average psi in all cylinders 127 lbs, all new parts that everyone said was my problem which wasnt. Now my motor screams with power. The 23 pitch prop was just to much for my boat. I am very happy with my results. I am running 40 mph not having to idle around the lake to fish anymore. My motor sounds awsome now running at WOT, Just like every mercury 115 hp i have ever owned sounds.

 

[arsenalpsu]

Re: 84 Mercury 115HP stalls out while advancing throttle

Well you are in luck, I was going through this same problem. I did everything these guys said to do on here, but now i am starting to believe they not the people you should ask the question to. Since they don't think to tell you what the problem most likely is. I will make it short and sweet to you, My 1984 Mercury 115 hp was stalling at 1/4 throttle, i was told to do everything you will find in every forum on the www and noting worked. I called every master Mercury Mchanic who had 40 pluss years experience i was told to call. The next to last one i called told me i needed new reeds, hummm dont see how that would make it stall when it had none of the symptons of bad reeds. Then I emailed a guy who has a atricle on this forum about how to time your motor and adjust the carbs. I was getting ready to buy a new powerhead off him cause i was told i needed a complete overhaul to fix my supposingly bad reeds. He sent me back a email telling me to call him that a new power head would not fix my boat. He said to change my prop down to 20 pitch and it would fix my motor. so i did one better went down from a 14.5 X 23 pitch to a 13 X 19 pitch with this i gained 800 pluss RPM and my boat shot out of the hole and never looked back.. before i couldnt get but 1400 RPM before it would stall, now i am WOT 6200 rpm which is more than i want but i will throttle back to 5200 when i am running it.. The lession here is going down in pitch gives you around 200 more RPM's per inch. So my advice is check your prop pitch and go down to 19 at least. Then your boat will work awsome. Please let me and everyone else on here with this problem when you do this and it fixes your problem. I got my prop right here off this site for 85.00 much cheaper than 999.00 powerhead was going to be.

Before you start badmouthing everyone on here maybe you should think about how you went about asking for advice. Most problems on here happen when the boat was working fine and then something went wrong. You must have had issues with your Merc since you bought it or put it on a new boat. Something as simple as a Prop most of us assume you already have the correct one on there AND THEN something went wrong. ANYONE who knows about in-lines knows a 23 pitch is way too much for most boats, they like to spin, not be lugged. Seems to me it's your own dumb @ss fault for not educating your self, WHICH YOU MUST DO IN ORDER TO POST CORRECT QUESTIONS AND GET CORRECT ANSWERS. If it was a simple oversight than so be it but no need to be a b*tch about it.

 

[arsenalpsu]

Re: 84 Mercury 115HP stalls out while advancing throttle

AND before you went to buy these new parts (assuming they were mostly electronic), did you get a tester and actuially do any testing to make sure they were having issues???

 

[partytymekaraoke]

Re: 84 Mercury 115HP stalls out while advancing throttle

I don't mean to be bad mouthing anyone here, I just feel that he is getting scarry advice leaving him to believe like me that we got burned on the motors we bought. So i was shedding some light to him that maybe it can be the easiest fix and cheapiest fix by trying a lower prop. Instead of having all the things mentioned above that i have read and tried on here that does not fix it. I replaced my fuel pump, cleaned my carbs not one time but 3 times blowing out all needle jets, replaced all gas lines, replaced the priming bubble, replaced coils, and more stuff. not one of these things helped my problem one bit. I went to the river screwed all idling screws in all the way, started backing them out 1/4 turn at a time, didnt help. I called mercury dealers in louisville ky everybody wanted 80.00 a hour to just try to figure out the problem. I started surfing the www and called and emailed every mercy tech i could find a number to or email address. Each one had a different ideal of what was wrong with my motor, one said my reeds were bad and the power head had to be rebuilt to fix it. Then i figured i would just buy a new rebuilt power head from a person in florida this is where i found the answere to my stalling, Instead of taking my money and selling me a new power head he told me to call him and he would tell me what to do to fix the motor. Once i told him it had a 23 pitch prop on it he told me to go down to a 20 and it would fix my motor, that the boat was over proped. So i got a 19 and the rest is history.
Now I bought this bassboat on craigslist for 3000.00 dollars, I went to see it and had the guy start it and put it in gear on a water hose. It run great so i bought it. Then when i went to go fishing i found out i had got suckered and the motor had problems. So this is what lead me to searching for a fix to the problem i had. If i had known anything about props working the way they do i would have probly figured out it was over propped. But i assumed a prop was a prop and it did look pretty and shinny. As you look at what the guy said above he bought a 1984 115 mercury and was happy, till it did the same thing on stalling. So as i was saying to him cheek your prop size and this will most likly fix your stalling problem. Now i have a Mach 14.5 x 23 pitch stainless steel prop with no dings and chips for sale that fits a mercury 115 hp. the 1st 200.00 gets it.

 

[asm_]

Re: 84 Mercury 115HP stalls out while advancing throttle

...I called mercury dealers in louisville ky everybody wanted 80.00 a hour to just try to figure out the problem. ...

Hmmm.... correct me if I'm wrong, there are people who do this for living. Meaning, they need to get pay to figure out the problem. No offense, but if you end up doing a bunch repair that wasn't needed, it's the price you pay for trying to be a free loader.

B

 

[444]

Re: 84 Mercury 115HP stalls out while advancing throttle

partytymekaraoke's suggestion could have merit if this is a new combo that's never been out on the water before. If the OP had a boat/motor combo that was running fine, then one day started acting stupid without making any other changes, then partytymekaraoke's suggestion would make absoloutely no sense.

 

[Blevins]

Re: 84 Mercury 115HP stalls out while advancing throttle

Just wanna shoot out my opinion. Most problems I have seen with lack of throttle response or "bogging" out is fuel related. If you have an inline pressure gauge that is best. Try the pressure before your primer bulb and after your primer bulb. Check and make sure the fumes are being expelled from your tank properly or the vacuum won't work properly. Good luck. I hope you have a fuel water separator w/ a view bowl to check for water in the fuel.

 

[partytymekaraoke]

Re: 84 Mercury 115HP stalls out while advancing throttle

ASM yes these people get paid to solve problems, but who wants to pay thousands of dollars for them to put on many new parts and still not fix your problem. If you go back and read post on this forum and other forums you will read that many, many, people have had their boats in the shop and spent tons of money on the repairs for when they get it home it still does the same thing. Now if you are rich then go for it. Most of us out here cant afforde to pay that kind of money for problems that end up not getting fixed, this is why there is forums on the internet for people like me who want to save the money and fix it ourselfs. I am a auto mechanic, a small engine mechanic at home depot tool rental, and i have not seen anything yet i cant fix myself and save the money. I was going to tear down my motor and rebuild it my self cause the supposingly Mercury Mchanics would not give me some kind of idea on a price to rebuild mine. They said well we want know till we get into it on what we will have to replace or fix. To me that is saying give us a OPEN Check and we will brak the bank. Sorry but its not going to happen on my shift. Now if people didnt want to try to fix their own problems then they wouldnt need advice from you. Which as i stated is scary and leaves people wasting money fixing things that don't need replaced. You go back and read the forums and you will see tons of advice givers saying this is your problem and then the person goes and replaces it, then they come back and say that did'nt work. Then they get told to try something else and spend more money that still don't fix their problems. So i feel if somones motor just out of the blue started stalling then your advice would be good advice to check. But when they buy another motor and its doing the same thing, then it would be a good idea to check their prop size and see if its over proped, specialy since the motor may have came off a lighter boat and had a bigger prop put on it.
I said the guy who helped me was in florida, i had it wrong he is in South Carolina, He should be the one on here giving out advice since he nailed my problem and not one other person on this forum anywhere ever told someone that maybe i was over proped. I hope this guy tries the prop switch that i said, then he comes back here and post his results. I am betting he will be glad he changed props. If it don't fix his problem then he will have to have a bigger unseen problem. I came on here to give this person a little hope that most likely is his problem since everything he has stated is excatly what i went through, To help him avoid doing unnessary and costly repairs that will not fix his problem. Now the next person who comes and read these forums will have a little hope and try this. have a good day guys.

 

[asm_]

Re: 84 Mercury 115HP stalls out while advancing throttle

yes these people get paid to solve problems, but who wants to pay thousands of dollars for them to put on many new parts and still not fix your problem.

I think you are mixing the cases where people whom are actually paying to get their motor repair and people that are trying to get free advise online. Free advise is just that, free advise. Use it at your own risk. Now, if you are actually paying someone $80/hour to solve your problem, and they have failed to do so. You should take it up with the shop owner, and possibly small claim court.

B

 

[partytymekaraoke]

Re: 84 Mercury 115HP stalls out while advancing throttle

Thats what i said people come here for free advice and help. Most come here after they have already paid Mechanics to work on their motors and they still have the problems. I have read many, many, topics in these forums where people try everything that has been sujested to them and still have the problems. I have read where people have said they took their boat to the dealers to fix and it runs worse now than before. The biggest majority of them have already paid to have work done that did'nt fix the problems. Not just this problem other problems. Some just give up completely and sell their boat or buy a new motor. With me it was the simplest thing that i had over looked and as i said i assumed a prop was a prop so it never dawned on me to realise my motor was over proped. Once i was told to change then i went on a education crash course on how props work then i seen how that changing down will give me the needed RPM'S to plane out. Although i did go down 1 size or 2 lower than i should have and it has me in a 6200 RPM at WOT. Which i want mind since i can throttle back some and if i ever have a heavy load i will have extra RPMS to get out of the hole on. In my opinion if anyone ever ask me why their boat runs great on a water hose and when under load it stalls at throttle, then i am going to give them advice to check their prop size and maybe they need to go down lower in pitch. Now this is if this is a motor they no nothing about and they have just bought it. Now if it just starts doing this for no reason and has ran great for them everytime they have been out in it, and they have made no changes in props then i will tell them to check compression, check fuel supply, check carbs, check plugs to see if all is firing. Then if everything there is A ok then you start looking deeper into the possiblities. After all its all about trying to help someone who has a problem and wants to try to fix it themselfs. I may have came on a little harsh in my 1st post, but i will blame it on all the bad advice i got about what was wrong with my motor to only be disapointed when it wasn't. When i work on auto's i always trouble shoot the simple things 1st, before i got to step 2 and step 3 on possiblities. Trying a lower prop is a simple thing. Now since i have so many hours working on my motor i feel like i could rebuild one with my eyes closed since i see they are not much different from a 2 stroke dirtbike motor, just a little heavier. Anyway it would be nice for people to actualy come back and let everyone know when they got their problems fix on what it was that worked for them. This would give everybody a chance to compare notes. And i do agree with 444