Hard starting Merc 115

[Nickolas]

A strong battery helps too. If your cranking speed is slow, the fuel has a hard time getting to the back. The negative trim is a must.

Yep I just charged the battery and that didn't help any. Seems the only way it will start is if I squeeze the living crap out of the primer bulb until it overflows gas. Thats a hell of a way to start a motor. You would think that Mercury would have done something before releasing these motors for sale to remedy the problem. They did finally put the enricher valve on them but how many before that without it were sold. So most people without these valves with these motors on their boats have to squeeze the crap out of their primers to get their engine started. At least once you get it going it will start right up after you cut it off.

I got a 72 Evinrude 85 without any enrichment valve and it is basically just like the Mercury. It is harder to start than others but nowhere near as hard as the Merc. I don't have to squeeze the crap out of the primer to get it started. Just squeeze it until it is hard and crank it around about 10 seconds and it will run. So obviously the design of the motor is holding it back somewhat. Anyway at least I know what to do now and don't have to be embarrassed at the dock with a motor that won't start. The Mercury is the only motor I have ever had that has left me at the dock stranded and not starting. I was cussing this big old damn motor the last time I took it out and told myself if I had an Evinrude or Johnson I would have been out in the water already...


Nick

[Robby321]

I think its more of a "age" thing than design. My XS 1500 back in the 70's was a almost instant start, heck, one time with a dead battery, I roped it to start! Stuff wears down, reeds, choke plates, gets out of sync, and for sure, the crap we get more gas, aint what it was once. Heres a read I saved on Link and Sync. Guy that wrote it a long time inline wrench...

Manual specs are different for each but this is close enough to get them all REAL close. This assumes nothing is broken or "wrong" with it. This also assumes that the timing pointer is properly adjusted (if adjustable) to accurately read TDC of the #1 piston.This basic procedure will work for all the 2/3/4/6 cylinder inlines from 1960 to 1988. It's not for the newer 3 and 4 cylinder loopers. Engine off. Disconnect throttle cable. Pull throttle arm to full throttle and verify carbs open fully. Adjust main throttle stop so that the carbs are JUST hitting their own little throttle stops. The idea here is that you want the screw stop and NOT the carbs acting as the "final stop" for your throttle lever. Return the throttle to idle, carbs should be closed. Set all idle screws to 1 3/4 turns out from lightly seated. Remove all plugs except #1, hook a timing light to #1. Then follow the narrative. When the throttle is in the idle position the carbs should be fully closed and the ignition retarded. It is the amount of retardation that determines your idle speed and is set later with the idle stop screw. Timing Event One - throttle pickup. As the throttle is advanced, the spark timing advances toward TDC and then to before TDC. As the timing is just passing TDC the 1st (minor) throttle pickup should hit and start to open the carbs. Use the timing light. Adjust the tang or trigger screw to make this a reality. All of them are speced different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win. Use the timing light with a friend cranking it to complete this setting. Timing Event Two - max advance. As you continue to advance the throttle the timing will advance while the carbs slowly open a bit more. The next adjustment is max advance, this is the point where the distibutor (or trigger) can advance no more. Set the max-advance stop to 21 degrees for "direct charge" crossflow inlines and 34 degrees for the older plain vanilla crossflows. Use the light, - err to the side of caution. Right after max advance, further throttle motion should cause the second throttle pickup to hit and open the carbs to full. You already set that -now verify it. Leave the throttle cable disconnected and go to the water. Leave the boat strapped to the trailer and back it in so it's deep enough to run. Have a friend crank it while you operate the choke and throttle. Warm it up at 1500 rpms's.When "warm" adjust the idle stop screw for about 800 rpm and then adjust your idle needle(s) in (one at a time) till the motor stumbles. Quickly backing it out 1/2 turn from "stumble" will usually save it from needing a re-start. Do that for all the idle screws. Re-set idle stop for 800. Now have your friend put it in gear (make SURE you are on the transom NOT in the water) and reset your idle stop for as low as you can get it. 500-600rpm is great if your old reeds will let it idle that low in gear. Now, re-adjust the idle screws, in to stumble, then 1/2 turn out. When you've gone back and forth with that a few times and have it "perfect" - adjust each one out 1/4 turn. Reset the idle stop so that it's about 700-800 out of gear and 500-600 in gear. Sometimes bad reeds won't let you get that low, you've GOT to get it under 1000 in neutral (worst case) to avoid beating up your lower unit when you shift into gear, even 1000 is "bad" but like I said "worst case". Now adjust (and hook up) the throttle cable so that with the shifter in neutral, there is light to moderate pressure holding the throttle arm against the idle stop. Take the boat off the trailer and go out in the water. Try the hole shot. If it falls on it's face try adjusting the idle screws out 1/4 turn at a time (all of them together) till you can get a hole shot. You can kind of do this on the trailer at the ramp, but it's not really safe for you, the boat, or the tow vehicle.You're done.-W
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[Mark75H]

You would think that Mercury would have done something before releasing these motors for sale to remedy the problem.

They did, its the fast idle lever. Works very easily, the motors start great. Mine cranks about 20 seconds cold to start.

Are you sure you do not have the throttle/shifter that releases the shifter by pulling the handle to the side before pushing it ahead ... giving throttle only?

[Robby321]

It is the deluxe box offered by Mercury. You push in the square button for throttle only and move it forward. If you move it all the way forward your engine will flat out scream if and when it does start. I just scanned the pic from the service manual. Anyway I move it all the way forward and then bring it back about half way. So it has me scratching my head at the moment.

Attachment 243246

Post #9 for pic the box

Think we are onto something here. The older box, fast idle lever increased advance, but the carb blades stayed closed (idle anyway), and with the choke plates closed, decent vacuum to pull gas in. Now on that newer box, if you go anywhere past advance, you will open the carb blades, and then only 2 choke plates to do the work. I would try and mark a spot on the box where on start, timing advances, but not throttle. Make any sense? That would be similar to the old Fast Idle box lever.

[Dave S]

The Valve is on it's way. You will have to install.....

[Robby321]

The Valve is on it's way. You will have to install.....

And on install, ..(see my post, #6)..you will need to pull at least the starter off, to get to the "stuff" I'm pretty sure my Merc guru has a pic, one installed. Have to shake his email box, ask. And the one I got off Ebay, coming soon too. Next time I need to dig into the motor..(not planned!), I will add one too.

Dave, to ya, doing what I do too. I got years of stuff, dragging knuckles earth 61 years now, and I also ask nothing, someone needing what I probably have. What goes around, comes around. Hell with the money...some needs help, simple do it.

Let me ring my Merc gurus bell, some install pix..enrichner.

[Robby321]

Also, I a big fan of NGK plugs..(BUHW, that merc)..as never a real impressed, anything Champ. My Harleys foul then too easy, the dirt bikes hate'em, my old 20 footer, does it all, Bayliner Cuddy, 1988 125 Force "dogs boat", (BUHX on it) with a STILL running strong motor in saltwater?..(aint the boat, its the owner!) fouled the champs too. Of my 3 boats, its the one thats ALWAYS works!

Try the NGK's ...(I'm getting that feeling, as Champs made Mex now..aint worth a crap, but were at one time..here)

Pic my "Pirate doggy!"

[Nickolas]

The Valve is on it's way. You will have to install.....

Dave,

I received the valve today. I really appreciate your generosity and lending a helping hand to someone you just met. As soon as I get time or the weather warms up I will start this new task and hopefully it will cure my problem. With it getting late in the season and it turning colder outside it may be spring before I get around to it. At least I have this part now so when the time comes I'll be ready.

So thanks again I appreciate it...

Nick

[rmessina]

i know there was like 100 different suggestions here but have you taken into account that there is ethanol in the fuel, and the deep creep barks off rich and will kill the plugs. Fatten up the mixture screws and btw never go off the manual for mixture settings on carbs they work when it is new u need to set the throttle at about 1/4 throttle and crank it. hope this helps. and you absolutely can flood this motor with the choke plates closed it is pulling all the fuel out of the bowls and sucking it riught in if it doesnt start right away it is prob flooded and stop choke and advance throttle to wide open crank for a few seconds and repeat if neccessary you shouldnt have to though...

[Nickolas]

i know there was like 100 different suggestions here but have you taken into account that there is ethanol in the fuel, and the deep creep barks off rich and will kill the plugs. Fatten up the mixture screws and btw never go off the manual for mixture settings on carbs they work when it is new u need to set the throttle at about 1/4 throttle and crank it. hope this helps. and you absolutely can flood this motor with the choke plates closed it is pulling all the fuel out of the bowls and sucking it riught in if it doesnt start right away it is prob flooded and stop choke and advance throttle to wide open crank for a few seconds and repeat if neccessary you shouldnt have to though...

Every time I mix a tank of fuel I always add in PRI-G and it seems to work well at combating the Ethanol and also it stabilizes the fuel for quite some time. I have never had any issues with Deep Creep as a starting fluid and it recommends it for this right on the can. Deep Creep is great stuff which is basically Sea Foam in an aerosol can. I use a little as that's all it takes. As for carburetor settings... I have been an mechanic for quite a few years and rebuilding carbs was my specialty. I never go by the manual as I set them by how the motor responds to the settings and plug color. I know what I am doing but am new to Mercury outboards. I have always had an OMC engine such as an Evinrude or Johnson outboard. I am very familiar with those but getting familiar with the Mercury engines.

I really like some of their designs of componets on their outboards and find them quite easy to work on. Granted I only have the one engine but so far a breeze just like the OMC engines. Just different designs and such but they all pretty much work the same way. Until I get the valve installed I am just squeezing the primer bulb to overflow the carbs and put the throttle part way and it has been starting ok. I asked the question in the beginning to see what the Merc users had to say since they are familiar with these engines and I am not. As time goes by I will be working with these engines as easy as the others I have. It is an impressive engine and I love the torque and sound of it screaming at 5800 rpm's... And of course I appreciate all of the responses to my question.

Nick

[rmessina]

squeezing the ball to force fuel past those can be a bad thing. are the float needles on springs on that motor ? if the deep creep works stick to it. i was thinking of something else if ur only using a little bit it wont hurt the plugs. i personally owned a 90 tower (with distributor) when i was 14 on a 92 16' chapparral that boat and motor combo was awesome didnt have anymoney and had to figure out how to fix it myself think thats the reason i went into the industry in the first place perfect blend of torque and top end great motor wish the carbs were designed a little better though and motor was very thirsty, of course i was 14 and ran it wide open everywhere lol

[Nickolas]

+

squeezing the ball to force fuel past those can be a bad thing. are the float needles on springs on that motor ? if the deep creep works stick to it. i was thinking of something else if ur only using a little bit it wont hurt the plugs. i personally owned a 90 tower (with distributor) when i was 14 on a 92 16' chapparral that boat and motor combo was awesome didnt have anymoney and had to figure out how to fix it myself think thats the reason i went into the industry in the first place perfect blend of torque and top end great motor wish the carbs were designed a little better though and motor was very thirsty, of course i was 14 and ran it wide open everywhere lol

This is an engine with springs on top of the float yes. I don't like overflowing the carbs with fuel and having it splash all over the place either but thats the only easy way it seems to start these motors without the fuel enrichment valve. And yes it is a VERY thirsty engine indeed. The first time I took it out I filled a 10 gallon tank of fuel and emptied it in a half hour I think. I was really surprised at how fast the fuel vanished from the tank. My girlfriend said we are empty already??? I said yep the tank is about sucked dry. Of course I told her this is a different boat and motor and 115 HP is going to drink a lot more fuel than the 60 HP I have on the Bass boat.

*The boat rides soooooooo nice and cruises well with this motor I really like it but damn does it drink the gas. It wasn't running all that good when we first got it and was starving for fuel bad. I could get it to 2/3 throttle and it started chugging and bogging down and I had to back off the throttle. So I took all of the carbs off and the floats were so out of whack I couldn't believe it was running at all. So after making the adjustments I put it all back together and took her out and hit the throttle and she flat out screamed and went to 5800-6000 rpm. Before I could only get 5000-52000 rpm's and that was all she had.

*This is my first Mercury engine and the more I mess with it the more I like it. Only factor is fuel consumption but oh well not much I can do about it. I'll just have to fill the tank when I take it out and TRY not to push the throttle all the way forward too much but that will be hard. I just love speed and the sound of a screaming two stroke is music to my ears. I think after awhile I settle down a bit it's just the fact of having a new boat and motor and experimenting with it. The motor is very clean and has excellent compression so it's in good shape as far as I can tell.*

*As you said you were 14 and ran it WOT everywhere... Well I am going on 48 now and I still run it WOT pretty much all of the time. I have always had the need for speed. I had quite a few muscle cars when I was younger and also having three older brothers all with toys to tinker with I got hooked on speed at an early age. Nothing like a big block 4 speed and a 4.11 posi rear. Now I get my speed fix on the water. Can't pull motors and swap rears like I used to after three back surgeries so now I just mess around with outboards. Very easy to work on and take off the boat if needed. Anyway when spring gets here I'll take that fuel enrichment valve and install it and then I shouldn't have anymore problems with starting this beast...


* * Nick

[Mark75H]

thats the only easy way it seems to start these motors without the fuel enrichment valve

I do not have the enrichening valve and mine starts with about 20 seconds of cranking every time from cold ... about 4 cylinders when warm.

[rmessina]

sweet! good luck with the valve let me know how you make out or if you need a new one i have a bunch laying around that i could definately part with need to start emptying the bottomless pit bottom drawer in my tool box lol

[Nickolas]

I do not have the enrichening valve and mine starts with about 20 seconds of cranking every time from cold ... about 4 cylinders when warm.

*And do you squeeze the crap out of the bulb or just squeeze it until it gets hard like normal without overflowing the carbs? I have an old Evinrude 85 with only an electric choke and no fuel enrichment and I can easily start that motor with normally squeezing the primer bulb until it gets hard and then turn the key and she will fire up every time in about 10 seconds. But that Mercury is one cold natured beast and it wont start like the Evinrude unfortunately. I have cranked the living crap out of that motor until the battery was getting weak and no start. But when I overflow the carbs or give it a shot of Deep Creep she will fire right up...