4.3 MPI slow to start

[andrewterri]

2014 Mercruiser 4.3 MPI cranks for about 3 or 4 seconds before starting. It takes much longer than my pervious 3.0. It has always started consistently in the 3 to 4 second range. I figured the engine is cranking to get oil pressure before the computer allows the spark to occur. This was my theory until today. The boat for the first time today got spark and kicked over briefly after only a second or two. The boat than went back to cranking like normal than started just fine. Are these engines just harder to start because they are in boats where the yoke and impeller must be turned with the engine? Is my theory right, are the engines building oil pressure before the computer allows the spark? I'm really not concerned as the boat always starts but after today it got me wondering why this engine takes so long.

 

[alldodge]

I would say this isn't normal for an MPI motor, or at least for anytime after the first start of the day. Mine cracks for a few seconds when cold, but when warm it usually fires before the motor makes one revolution.

Being a 2014 it should be a catalysis motor so there could be other things that need to be checked before starting. have not herad this before, and going to do some looking

 

[andrewterri]

Thank you Alldodge. It is a cat engine. We are heading to the marina now and I will make a video or at least time the engine start.

 

[Maclin]

"yoke and impeller must be turned with the engine"

The 3.0 you had would have been in the same configuration if it was a MerCruiser (or any) I/O sterndrive

My 4.3MPI takes about 3 seconds almost every time. Might be more than 3 and on the way to a full to 4 seconds, I am getting used to it and don't think it is a problem. Occasionally it starts right up if it was just sitting for a couple of minutes. Do you wait for the fuel pump to finish its' cycle after your turn it on before you crank?

Also the MPI's do need a good charge on the battery, both to spin the engine well and for the electronics.

 

[QBhoy]

Maclin is spot on.
With the mpi, you need to turn key and wait until the fuel pump stops. Turn key and within 2-3 secs it will start.
As also mentioned, the battery ALWAYS needs to be tip top. These MPI’s fundamentally depend on it.

 

[andrewterri]

I always wait for the pump to pressurize before starting. I got into this habit with the john deere. I timed the start today and it was 3-4 seconds. I guess that is normal. It starts right up each time and died once today but I think that is because I was riding the throttle into neutral not making my mind up if I wanted to go closer to shore or not. I got the alarm and engine died. Started right back up and ran fine. Think I engaged the interrupter switch and left the throttle there which caused the alarm and killed the engine. Thank you guys for sharing your input and putting my mind at ease. Now I know the slow starting is normal. I will make sure to have the battery switch set to both batteries.

 

[Maclin]

The shift interrupt kicking in is kind of a weird feeling to me, not used to a Mercruiser Alpha. And especially having a more or less modern MPI style engine, when it kicks in for a split second my brain goes right to "Told you not to get the MPI over a Carb" , lol. Most previous boat I had was an older Volvo Penta drive that did not use nor need the interruption. You do need to be firm with the Alpha when coming out of gear, and not uncomfortable with your decision .

 

[Maclin]

I jut started mine in the driveway today, it goes like this every time in a cold start... chugga chugga chugga chug flub blub blub blubble flub purrrrrrrrrr.

 

[Maclin]

Mine has a fresh fuel filter and a nearly new cap and rotor, though it started the same way before I changed them. You may want to take a look at the cap and rotor, they seem to corrode quickly nowadays.

 

[andrewterri]

I will check out the cap and rotor to see how they look. We usually do a mid season fluid change because of the high usage and I'm thinking about taking the boat to the dealer. I always do my own fluid changes and work, but I would have them check the core plug that was replaced along with checking for any stored codes that have been thrown. I could just have them check the cap and rotor as well. I wish I had the mercruiser software to do things myself. Does anyone know if Smartcraft can read codes or at least tell you in real time when it happens so you know?

 

[alldodge]

Finding hard start symptoms but always with other issues. No luck finding new motor with hard start issues reported.

The shift interrupter should have no issue on ignition going into gear, it only works coming out of gear unless its not adjusted correctly

You do have the Crap cap and these are known to have issues without warning

 

[andrewterri]

thank you very much for looking alldodge. I was coming out of gear when it died. I was moving the shifter slowly and thought I stop shifting into neutral but I think I was still slowly moving it backwards and allowed it to get right where the interrupter engaged.

I am going to figure out how to pop that engine cover and to access the cap and rotor than find the part number and order one. I do not want to wait until a known problem is a problem. You don't happen to have the part number laying around for the cap and rotor I need? I am sure its not easy access like the 3.0 but I want to get it changed.

 

[alldodge]

The Merc number is 898253T23
If you search for the muber several places will show up. Can also get the cap at your local auto parts store or online looking for GM V6 distributor cap

 

[Maclin]

Dist Cap 898253T23
Rotor 8M6001222

Save your screws just in case, the ones I got with my order did not fit for some reason.

 

[andrewterri]

Thank you guys for the part numbers. I am getting them added to the cart now.

 

[muc]

The oil pressure doesn't matter during starting.
SmartCraft will tell you something's but diagnostic software is needed to find your problem. I would be looking at the misfire counter and cam timing after checking the basics.
On a MPI engine, you shouldn't be able to feel the shift interrupt work and your engine shouldn't die no matter how slow you shift.

 

[Maclin]

When I am backing out of a slip then go to neutral then forward I can feel the stumble.What do I need to fix?

 

[muc]

When I am backing out of a slip then go to neutral then forward I can feel the stumble.What do I need to fix?

without a serial number, I don't know exactly what you have.
But some things to look at.
Tight lower shift cable
weak V spring or binding in shift block
weak shift assist
shift cable adjustment
miss adjusted in gear switch or shift interrupt switch

sometimes it can be a combination of slightly worn parts working together all the way from the control box to the shift spool.

I have had customers with multiple boats that are willing to pay large amounts of money to track down minor engine stumbles like this in one of their boats. But for most owners a slight stumble is not a big deal.

But the engine should never never die no matter how it's shifted.

Oops, just reread your post. If you are feeling a stumble when you shift from neutral to forward then you could have problems not related to the shift system. Maybe you should start your own thread about this problem?

 

[Maclin]

More like an eyelid winking, just as it comes out of neutral. Not that big a deal to me yet, thanks.

 

[QBhoy]

More like an eyelid winking, just as it comes out of neutral. Not that big a deal to me yet, thanks.

Totally normal Maclin...especially when cold. These things over fuel when cold and run prettt rough for a while and until you put some load on them.