Mercruiser Starting Issues

ShaneCarroll

Chief Petty Officer
Joined
Feb 10, 2009
Messages
639
Re: Mercruiser Starting Issues

Well, after all the strenuous testing, same result. It started fine over and over again at the house for 45 minutes, and I put it in the water, same result. I am completely at a loss right now. . .
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: Mercruiser Starting Issues

I still don't know what grommet? You got a kill switch? You testing for spark when this happens?

Did you try jumping it?
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Mercruiser Starting Issues

Runs it the house, starts fine, yet fails once in the water.

If this were an outboard I'd bet money that the idle mixture is set way too lean.

Cold start on the water you're pumping the accel pump and adding extra fuel, fattening the idle mixture to start.

Once you get it started and warmed up to temp (while ON the water), put it in forward gear THEN adjust the idle mixture to the best idle speed while in gear.

See it this doesn't improve your starting and restarting.
 

wkb2460

Petty Officer 2nd Class
Joined
May 4, 2008
Messages
146
Re: Mercruiser Starting Issues

Is the engine warmed up to operating temperature when it happens?
Could be vapor locking while hot.

Merc 3.0 was known for this. Don't pump the throttle, but open it up 1/2 to 3/4 of the way, then try to start it while hot.
For a cold engine, you have to pump it a few times then start.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser Starting Issues

OK, let's go back to your original post and get some questions answered:

I remove a little rubber grommet that does not allow any air out of the carburetor, and once it starts I replace the cap.

Bondo asked, but it never got answered, what is the "little rubber grommet that doesn't let air out"

I am somehow beginning to think this one statement may help us find your problem.
 

ShaneCarroll

Chief Petty Officer
Joined
Feb 10, 2009
Messages
639
Re: Mercruiser Starting Issues

I apologize for overlooking that question. You were correct, it is a vacuum plug. The boat will hardly start with this plug on, and it will idle very rough with the plug off. So, I start the boat, run to the engine, and replace the plug. I am not a very experienced mechanic, although most of the common posters on here probably already knew that. It does not get a spark. There is no kill switch, or, at least none that I can find. None at the helm, and none on the engine. Once the engine is warm, I have to have the throttle in neutral to start (no pumping whatsoever). It does not misfire or anything once started, I believe on another post, someone mentioned a distributor module, does that ring any bells? I checked all connections and wiring, as wiring is pretty much my bread and butter anyways, but I don't want to start pulling this and that off without prior knowledge. All wiring is good, I bypassed the gauges with that purple wire from the ignition, let it go straight to the engine, and then looped in the gauges. That seemed to help a lot, but still not solve the issue.

Once again, I thank everyone for their patience and helpful responses. I know I'm no expert, but imho I would have to narrow it down to the distributor or a component thereof. I guess it doesn't help much that with this issue, I will probably be replacing the starter before much longer.
 

ShaneCarroll

Chief Petty Officer
Joined
Feb 10, 2009
Messages
639
Re: Mercruiser Starting Issues

The vapor locking described it perfectly, and it starts much easier now, but still not good. Since spark plugs have been replaced, coil is fine, voltage is good, would it be the distributor module? Also, since the strenuous starting is draining the battery, would a dual battery setup with a battery switch be wise? If so, how difficult to install?
 
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