Question on starting cold-blooded Mercury 4 stroke

Hoping you all might have some thoughts.

My specs: 2009 Mercury 4-stroke big tiller. 75 hp.

On Friday and Sunday, really struggled to get it going. Had to jump it Friday, so battery was clearly one issue (load tested as bad). Put new battery in and while it started Sunday, had to crank it quite awhile before it finally caught and ran. Ran fine once going. And always started just fine once warmed up. Air temp was around 30 each morning.

Are these motors just normally pretty cold-blooded? No way to ‘choke’ the motor that I can see.

Thanks for any tips.

Are you priming the bulb until it’s solid before cranking?

i have to pump the absolute crap out of the bulb to get my evinrude to pop off.

shockers wrote:

Are these motors just normally pretty cold-blooded? No way to ‘choke’ the motor that I can see.

Are you pushing in on the key? I have 2007 60HP tiller. Turning the key to “start” cranks the engine over. Pushing the key inward while cranking, engages the electric “choke”. Don’t know if that’s the proper term because the engine is fuel injected, but it acts the same a choking a carbed engine.

You can always choke a carbed engine even if its not equipped with a choke. You simply cover the intake barrel of your carb while cranking it over.
Sometime you may have to remove an air box to do this effectively.

2009 Mercury 75 4-stroke-EFI.Possibly not getting proper fuel pressure,thus the extended cranking?Could be a failing fuel pressure regulator?EFI is normally turn-key,so should start the same regardless of temps.Just like an automotive engine.

Hmmmm. Thanks for the tips. Milemark, yes, I wonder if it could be something like you suggest. Starts pretty normally in warm weather.

Primer bulbs seem to be crap these days and the anti siphon valve in them fail all the time. That allows the fuel to flow all the way back to the tank. I had to install a separate anti siphon valve in my fuel line. If it takes a long time pumping the bulb to get it firm or if it doesn’t get firm at all, try replacing it.

To my knowledge, there’s no primer bulb on mine. It’s EFI. So…I maybe will check into that fuel pressure regulator idea.

shockers wrote:

To my knowledge, there’s no primer bulb on mine. It’s EFI. So…I maybe will check into that fuel pressure regulator idea.

I’ve never seen a boat without one??

If you don’t have one….you need one

I have an 08 merc efi that had that issue. First get a primer bulb, that will help. Check out the throttle linkage. Mine needed adjustment to get it to 0% throttle. It seemed to crank forever and then die a few times until it would stay running until I figured that out.

B-man wrote:

<div class=”d4p-bbt-quote-title”>shockers wrote:</div>
To my knowledge, there’s no primer bulb on mine. It’s EFI. So…I maybe will check into that fuel pressure regulator idea.

I’ve never seen a boat without one??

If you don’t have one….you need one

If you’ve never seen a setup without a primer bulb, you need to get out more. Both the guys I fish LOTW with do not have primer bulbs in their factory rigged fuel systems. If the fuel system is not designed for one, then one is not needed in spite of what you say.

My 99 Carbed Yamaha 50 hp 4 stroke is like this also. I have no way of choking it that I Know of either?

Mercury motors need a high RPM before the injectors will fire. I would change over to full synthetic oil, it helped with my motor on P4 in the winter time. My 2 cents.

Yeah….I was wondering about trying the full synthetic route. I only have a few weeks (before, sadly, boat goes into storage) where it might be an issue. But…seems like that’s another option. Like I said, it’s never been an issue in warm weather.

Conventional oil has a lower viscosity in a warmer weather, as it gets colder it get thicker lowering your RPM on start-ups, until the friction warms the rings, and the RPM’s start to climb into the range it needs to start.

Yeah. My guess is it’s mostly just ‘cold-blooded’. My old two-stroke started better in the cold – but I could easily prime/pump primer bulb etc.

Just gotta hope my battery retains enough cranking power to cranking till it finally catches I guess. Or use full synthetic.

Or, get a heated garage really close to the launch. Heh.

I can’t see any downside to adding a primer bulb. There is no way that forcing the motor to build fuel pressure while it is cranking is going to be helping with this cold starting issue. If you have the access to the fuel line, it’s certainly a cheap possible fix to try and if it doesn’t work, the cost of removal should be a few feet of fuel line.

I would also agree with changing over to pure synthetic oil. This makes a big difference in cold cranking performance.

Oversizing the battery could also be a good move if the compartment has enough space.

Grouse

I have a 60 merc 4 stroke and it definitely needs some cca to start in the winter. I’ve yet to find anything other than a dedicated cranking battery that does the trick year round. The deep cycle/ cranking batteries do not seem to cut it when the temps really drop.

I did pull start mine in September and was surprised how easy it was.

TheFamousGrouse wrote:

I can’t see any downside to adding a primer bulb. There is no way that forcing the motor to build fuel pressure while it is cranking is going to be helping with this cold starting issue.

Given your logic of “I can’t see any downside to adding a primer bulb.” would that mean you would add a primer bulb to the EFI fuel system on your auto, truck or ATV?
As far as your second statement;
In the case of a EFI fuel system, the “motor” has nothing to do with the fuel pump pressure. The fuel pump is electric and is independent of the motor. Because the fuel pump (both the lower pressure pump and the high pressure pump) get their power from the battery, a low pressure condition may be an electrical issue.
The available voltage drops when the battery is called upon to crank the engine. Therefore there is less electrical power going to the fuel pumps, which may in turn produce less fuel pressure. This is one reason motors now require higher CCA than was called for in the past.

A primer bulb, will not increase the output of high pressure fuel to the injectors.

If the “cold start” issue is too low of pressure delivery to the fuel injectors, it could be one or more of several issues within the fuel system or electrical system.

On a personal note; The EFI fuel system on my boat does have a primer bulb. I can’t remember the last time I ever even touched it. Maybe that is why some systems don’t have one, the engineers have eliminated another potential failure point, by eliminating a primer bulb which no longer is needed in their system.

Here is an interesting read about fuel injected Mercs

http://www.marineengine.com/boat-forum/showthread.php?413267-Mercury-60-HP-EFI-4-Cycle-Bigfoot-Problems

It provides a lot of insight into fuel injected outboards.

They have a VST in the system that is the high pressure pump sits in. Here is a link to the YouTube video that add to your knowledge base.

worth watching.

Hope this helps… Fish On …

dbright wrote:

I have a 60 merc 4 stroke and it definitely needs some cca to start in the winter. I’ve yet to find anything other than a dedicated cranking battery that does the trick year round. The deep cycle/ cranking batteries do not seem to cut it when the temps really drop.

I did pull start mine in September and was surprised how easy it was.

X2 on the easy pull start. I had two cranking batteries go bad and had to pull start. It takes the same effort to start a 2hp ice auger. Just make sure you have the wrench to pull the flywheel cover off.

djshannon wrote:

Hope this helps… Fish On …

Good information, thanks for joining the discussion.

Dave maze wrote:

<div class=”d4p-bbt-quote-title”>dbright wrote:</div>

I did pull start mine in September and was surprised how easy it was.

X2 on the easy pull start. I had two cranking batteries go bad and had to pull start. It takes the same effort to start a 2hp ice auger. Just make sure you have the wrench to pull the flywheel cover off.

Glad to hear that. I have a 2013 60hp Merc (4-stroke) too.

Really appreciate everyone’s input. Super helpful.

My assumption, at least in my case, is it’s mostly a viscosity issue. So, unless I put full synthetic in, my guess is my motor is just bound to be always cold-blooded in low temps for starting. It starts fine in warmer weather, so I don’t know that there’s an electrical fuel system issue – doesn’t seem like it based on all of your feedback.

In my case, I think my 75 hp 2009 Mercury Big Tiller EFI motor is the same block they use in the 90 and 115. Thing is super heavy/big block. No idea in my case if that has any impact. I did see that Mercury went to a smaller sized engine starting around 2012 or so I think.

Anyway, again, thanks so much for the tips. I may have to also experiment with pull start – just in case.

Maybe not an EFI thing, but carb motors can be touchy about starting the first time of the day if they aren’t trimmed ALL the way down.

Do you charge your starting battery? Just the alternator from the motor running is often times not enough to keep the battery fully charged. Batteries also lose efficiency in cold weather so even if it is a “new” battery it may be partially discharged if you don’t charge it between trips. (Your battery will also not need to be replaced as often if you keep it fully charged.)

For an EFI motor it is likely low fuel pressure, partially clogged injectors or a temp sensor is faulty telling the control module it is warmer than it is. I see the video covers what the fuel pressure should be. My Mercury 40 EFI starts great in cold weather except for 3 years ago when it wouldn’t start at all until I replaced the electric high pressure pump, glad I tried starting it at home