Mercruiser 3.0 Engine Starting/Running Issue

[ivianiac]

I have a 1984 Mercruiser 3.0 that I bought and am having trouble getting it to start. I recorded a video so that you can hear what it is doing.

What I have done so far:

It is getting fuel and spark, it wasn't when I bought the boat. I had to install a wire from the points in the distributor to the coil.

Also the fuel pump vacuum from the pump to the carb was clogged with a green sticky substance. I cleaned both of those fittings and replaced the line, pump is now working. I replaced spark plugs. The coil, wires, condenser and points look to have been replaced before I bought the boat and are functioning properly. Now the boat is getting spark and fuel, I can smell the fuel and it sounds like a cylinder or 2 is firing then it gives up.

Any help would be appreciated.

I also want to remark what a great forum this is, troubleshooting the first two issues would have been impossible for me without this website

 

[thumpar]

Re: Mercruiser 3.0 Engine Starting/Running Issue

When you say "fuel pump vacuum" do you mean the clear line? That line is used when the fuel pump diaphragm fails. Fuel goes into the carb instead of the bilge. If you have fuel in it then the fuel pump is bad.

 

[Bondo]

Re: Mercruiser 3.0 Engine Starting/Running Issue

Ayuh,.... Finish yer Tune Up,....

New points, set the timing, 'n dwell....

 

[ivianiac]

Re: Mercruiser 3.0 Engine Starting/Running Issue

The clear line does not currently have gas in it, I didn't know what it was for. When I bought the boat it was completely blocked with a greenish / yellow thick sticky substance. I assume it failed previously and the gas gelled up? It is brand new clear line now.

When it was clogged the diaphragm couldn't expand to pump fuel, so clearing the clog in the fitting "fixed" my fuel pump.

I can't think of anything left to the tuneup. I can't get it running to set the dwell and proper timing but I did properly adjust the points gap to spec. and I set the timing to approximately correct (moved timing line to TDC on the compression stroke

I replaced all spark plugs and properly gapped them. The plug wires, condenser, points and coil all seem to have been replaced and never used by the previous owner (the parts boxes where in the boat still) Also there is no sign of use on the parts.


I still have yet to do an oil change but don't think that is attributing to this problem.

 

[RiggerMark]

Re: Mercruiser 3.0 Engine Starting/Running Issue

mornin, sounds like it wants to run, my guess is gummy carb, these 2bl marine carbs, combined with todays fuels, seem to gum up pretty quick, if the motor sets a season, almost always gotta rebuild carb, it can look as carb working, ie gas entering intake, but its doing it all wrong, passages in body clogged, if ya got spark at the plug, nice inch long blue arch, checked that tdc #1 is right, (180 degrees out possible), then all ya kind of got left is your fuel, tank, vent, pump, and carb, none of this sets long well, myself, not a big fan of starting fluid, but might try a couple small sprays, choke opened throttle closed, should run for a couple seconds, take it easy with the fluid, nasty stuff, anywho, you'll get it.... let us know how it goes.............Mark............as i reread your post, seems like i'd start at that gummy pump, if that dump line was nasty, everything connected to it should be nasty also.......gotta be a fuel issue... pull your line off your carb, direct it into a jug, unhook coil wire from cap and ground it on block, turn motor over, watch your pump in action, if that's the upside down, carter pump, it sprays a pretty solid stream, also keep a fire extinguisher around handy.........

 

[Don S]

Re: Mercruiser 3.0 Engine Starting/Running Issue

Put the shifter in throttle only, pump the throttle a couple of times to prime the engine and leave the throttle up to about 1/4 and start it up. keep the rpm in the 1200 to 1500 rpm range.

 

[ivianiac]

Re: Mercruiser 3.0 Engine Starting/Running Issue

Thank you all very much I finally got to hear my boat run. After charging the battery I just held the key down for a while until it turned over a few times in a row. I think there was garbage gas in the carb bowl. I drained the tank and lines but didn't know how to drain the bowl. I may end up rebuilding the Carb just to be safe.

I didn't run it for long because the trim wiring is all messed up so I can't lower the out drive and I have read you can ruin the u joints running it with the out drive up. I did put muffs and water on it and my impeller seems to be working.

I'm learning a lot about boats and thank all of the community members here for their help.

 

[fishrdan]

Re: Mercruiser 3.0 Engine Starting/Running Issue

Do you have a water separating fuel filter, it's highly suggested. To clear the carb, pump the throttle a bunch of times, this will get most of the fuel out of the bowl, but not the garbage. Only way to clear the garbage out is to rebuild the carb and clean it up.

Don't run it with the trim all the way up. If you have to, remove the trim cylinders from the drive's aft anchor pin and drop the drive down.

If you don't know when the impeller was changed last, or if over 2 year, change it.

Check and/or replace the drive lube also.

 

[ivianiac]

Re: Mercruiser 3.0 Engine Starting/Running Issue

I didn't even think to disconnect the trim cylinders, that is a good idea.

I do not know how to tell if it is a water separator fuel filter. It looks like a standard paper filter.

Also shouldn't there be a filter before the fuel enters the carb? There is only the filter on the fuel pump. Also the pump is pumping very efficiently when I pumped it into a jug.

Is the impeller very hard to diy, the oil seems straight forward. The part with the impeller that makes me nervous is aligning everything on reassembly.

 

[fishrdan]

Re: Mercruiser 3.0 Engine Starting/Running Issue

A water separating fuel filter looks like an oil filter, about the same size and appearance. not stock on a 3.0L engine so you have to add one. There should be a filter in the carb's fuel inlet, behind the big nut fitting where the fuel line connects. Impeller is pretty easy as long as you do things "right", look at the stickies at the top of the forum, probably something there. Also, download the manual for you engine/drive over at 4share. Maybe someone can post up a link for you.

 

[Oshkosh1]

Re: Mercruiser 3.0 Engine Starting/Running Issue

Check these out...
http://boatinfo.no/lib/mercruiser/manuals/mercruiser10.html#/0
http://boatinfo.no/lib/mercruiser/manuals/mercruiser6.html#/0

Should help answer some questions/concerns...