3.0L merc Hot start issue?

[Wildman_fab]

I have a 1988 3.0L alpha I that runs VERY sweet, plenty of power, smooth, revs right up good. The problem I have is with a hot starts. I can throw the muffs on it in the yard and touch the key, it cranks 2X and fires right up. Once I get it off the trailer at the ramp it will crank just fine, but it wont fire up. I have to give it throttle till it almost floods, then it will pickup a couple cylinders. I usualy have to crank for a couple minutes to get it to go. It shuts right down if I turn the key off, it dosnt run on or 'diesel'

Warn out carb? fuel leaking into intake and flooding just after I shut it off? Its got an electric choke also if that makes a difrence.

 

[chiefalen]

Re: 3.0L merc Hot start issue?

Few things i would try.

Full tune up done last?

Points might be off, timing off? Points dirty? To wide a gap.

Clean all the connections, follow the neg cable to the ground clean it good.

Starter connections, clean them good.

Disconnect the battery before you start cleaning connections.

All the fuel filters clean? One in the fitting bye the carb, one in the fuel pump, and one on the fuel pickup tube.

Slav solenoid would actually be my guess. On the way out.

Clean those connections.

Hows compression.

Carb might need a rebuild.

But like i posted my moneys on the slav going.

 

[waterone1@aol.com]

Re: 3.0L merc Hot start issue?

I just don't get the above post about the slave solenoid. If all you were getting was a "click" I would agree the slave solenoid was suspect....but that is not what you posted. I also have to question the nature of your post ? You make a distinction between in your driveway and in the lake. Are you running the engine up to temp in your driveway ? If so, and the only difference is whether the boat is in the water or on the muffs, I would ask, when was the last time the risers, manifolds and such were changed ? When I hear " easy to start on muffs" but "hard to start in water".....I think of water getting into the cylinders. Not that this is a tell-all, but do you have any rust trails between your manifolds and risers or elbows ?
A way to verify or eliminate this theory, is to pull the spark plugs and look at them the next time the boat is hard to start in the water. See if there is any sign of moisture. If so, you need to deal with this right away....it will kill your engine !

 

[Wildman_fab]

Re: 3.0L merc Hot start issue?

I should clarify a few things. I dont have points the, previous owner converted it to the more modern pertronix setup. I have a brand new fuel filter setup as it didnt have any before.
I always start the motor in the yard before I go out, mainly because I go in the ocean and its a long swim back. LOL But it dosnt matter if its on the hose or in the water, after it warms up in either place its a bear to get it to catch again after you shut it down.
Last tune up was done last year along with new riser. Boat has almost no hours (1-2) since then as the guy lost interest after the main relay went bad and the starter soilnoid did too. I have replaced both of these with new parts. Is there a way to check if my carb is 'leaking down' I still have a gut feeling its flooding itself. It dosnt use a ton of fuel while weare runing it, maybe 1-2gal/hr depending on if we are fishing or cruzing.

Ill pull a plug next time I get it to warm up and it wont start.

 

[chiefalen]

Re: 3.0L merc Hot start issue?

Main relay meaning the slav. Might be called something else look like a different part but does the same thing.

The main relay has to be grounded to operate?

If yes take it off and clean under it so the relay grounds are good.

Clean the main ground, follow the neg cable to the ground, take it off clean the bolt and the wire and reinstall.

The starter wires are clean?

The battery cables clean?

Now the filters are all clean?

The carb rebuilt when?

The fuel pump giving you 4-6 psi?

Watertone i just went thru this issue myself.

Ok if the cleaning of everything don't do it the plug wires good?

That not the problem than run a jumper wire from the battery to the pos side of the coil with a switch.

Never,ever, never, leave the switch on unless your starting the boat than turn it back off.

Ok pump twice turn on the jumper switch start the boat.

TURN OFF THE SWITCH.

If this fixs the problem it's a bad slav-main relay whatever you want to call it.

YOU DO NOT WANT TO LEAVE THE SWITCH ON FOR THE JUMPER UNLESS YOUR STARTING THE MOTOR.

 

[Don S]

Re: 3.0L merc Hot start issue?

Seems to me this slave solenoid problem has absolutely nothing to do with it. He doesn't have problems with it cranking over, only problem is it not Starting/running when warm.

Once I get it off the trailer at the ramp it will crank just fine, but it wont fire up. I have to give it throttle till it almost floods, then it will pickup a couple cylinders.

Next time you warm it up and try to restart it, pull the flame arrestor off and see if the choke is open or closed. If it's closed, it's probably flooding a warm engine. Opening the throttlle wide open clears a flood condition and that's when it's starting

 

[JustJason]

Re: 3.0L merc Hot start issue?

and while your back there with the flame arrestor off......
with the engine warm and running, have a buddy shut the engine off. Look down the bore and see if it's still dripping fuel. a couple of drops isn't anything but if you have fuel pouring out your going to need to rebuild the carb.

 

[chiefalen]

Re: 3.0L merc Hot start issue?

I gave a whole list carb was on it. Freekin 20 year old boat needs a carb rebuild i bet anyway.

But after doing everything on the list on my 86 was the stikin g-d damn salv making me crazy.

Changed it out and fixed.

Wires could be bad on the plugs. Who knows. Maybe 20 year old wires who knows.

He got to do the list.

After all is said and done and if not fixed and you have 10 extra minutes run the jumper.

You can do it on the water on the trailer whatever.

I hope i am wrong and it's just a carb rebuild or something easier i don't wish you or anyone any problem with there boat.

 

[Wildman_fab]

Re: 3.0L merc Hot start issue?

Slave solenoid, slav, what ever you want to call it, its the main relay on the motor, located above the starter on the right side of the motor. It has been replaced, I DONT HAVE A CRANKING PROBLEM. Motor turns over fine like I stated before.

chiefalen: I think you need to re-read my newest post, tune up, etc was done already, boat has little to no hours on it since then. thanks for all the noob advice though it may help somebody else out in the future if they are using SEARCH.

I think ill start where Don S recommended thanks!

Next time you warm it up and try to restart it, pull the flame arrestor off and see if the choke is open or closed. If it's closed, it's probably flooding a warm engine. Opening the throttlle wide open clears a flood condition and that's when it's starting