Boating is fun?

[friendly_jacek]

Originally Posted By: freak007
Originally Posted By: friendly_jacek

BTW, this is the Mercruiser GM 4.0L 135 engine. Always hard to start since the day one.


I am guessing since you said 4 cyl that 4.0 is a typo.

the 3.0 is a 135hp GM industrial 4 cyl. Was also used in many forklifts.


If it has always been hard starting, I would go through the carb and verify the ignition timing. All of my carbureted engines will start in 1-2 pumps unless they have been sitting for 4-6 months. I have a restaurant style condiment bottle special for the times that they set for an extended period, a little squirt of gasoline into the carb and they are off... It may take you half a day to get it dialed in, but that half a day will greatly reduce your headaches later on.

Does yours have points, or electronic ignition?


My bad, I meant 3.0L (but 4-cyllinders).

It has electronic ignition. I was actually impressed how the engine was running OK (with the new plugs) with sparking coil.
Maybe the flooded plugs damaged the coil too?

I'm so glad I didn't crank it with plugs out as gasoline would shot out of holes right on the sparking coil. That would be some nice inferno.

 

[friendly_jacek]

Originally Posted By: SteveSRT8
That engine has a weak ignition, even if electronically enhanced. Get a spark box and open up the gap on the plugs (unless you are running gapless!). Then verify the carb for proper accelerator pump operation, check float, fuel pump, etc.

If it sits more than a couple weeks it just needs a bit of priming, just a teaspoon or so at a time, it should start almost immediately...


Should I increase the gap for weak ignition?
Funny that you mentioned that, as the merc manual mentions gap of 0.045 that is huge IMHO, but if you check online catalogs from Denso/NGK/etc, the gap is all over the place, but usually 0.035-0.040. Very confusing.

 

[SteveSRT8]

Originally Posted By: friendly_jacek
Originally Posted By: SteveSRT8
That engine has a weak ignition, even if electronically enhanced. Get a spark box and open up the gap on the plugs (unless you are running gapless!). Then verify the carb for proper accelerator pump operation, check float, fuel pump, etc.

If it sits more than a couple weeks it just needs a bit of priming, just a teaspoon or so at a time, it should start almost immediately...


Should I increase the gap for weak ignition?
Funny that you mentioned that, as the merc manual mentions gap of 0.045 that is huge IMHO, but if you check online catalogs from Denso/NGK/etc, the gap is all over the place, but usually 0.035-0.040. Very confusing.



Aftermarket spark box from Crane (my fav) will greatly increase the output. That allows you to open up a huge gap and FIRE something up!

 

[friendly_jacek]

I see. I had to google for ignition box. I learned something new.

 

[Tuffy1760]

I would trust a heavily used boat over one that has been stored a long time. Get boat running and sell. I could post my experience with outboard motors and trailer bearings but I just can't do it to you guys.

 

[Mad_Bad_Dad]

Hi. Just signed up today and noticed this thread.

If your coil is sparking to ground, your plug wires are shot. There is too much resistance in the wires for the spark to get to the plugs so it finds the easiest path.

I had a 1995 Yukon that started to run for [censored] at 40k miles, saw the sparks at the coil, replaced it and it didn't help. I replaced the wires and everything was OK. Your condition with the plugs being wet with gas could be caused by the wires, I would replace them first before you do anything else.

Boats are frustrating but fun once you get things worked out. Keep plugging at it and it will be worth it.

 

[friendly_jacek]

Thanks for chiming in. The wires are good. I replaced the plugs and coil and things are well (so far).

 

[car54]

Stories like this remind me why I got rid of my old boat and bought a new boat with an EFI engine.

Old boat (always broken down junker, $500):

new boat (never broken down, $500 per month!)

 

[Schmoe]

One word.....N I C E !!!!!!!