1990 Mercruiser 3.0 L Alpha One

I need help. I am trying to get my boat back in running condition after sitting for 3 years - in my garage in Louisiana. Prior to this the motor worked great - no problems - although 20 yrs old have only put 30-40 tanks of gas through it! However, it was left outside for a few months where water collected and flooded the starter and rusted it out - drain hole plugged with algae. I replaced the starter and battery and put in new plugs.

The boat sat with 1/4 tank of gas during the 3 yr period - no stabilizer was added when it went into storage. I added new gas on top of the old and tried to start the motor. It attempts to start - but the only way I can keep it (very roughly) chugging is to rapidly pump the throttle - can keep it chugging for 30-45 seconds - barely - but as soon as I slow down the throttle pumping - it immediately dies?? During the rough chugging it is backfiring every few seconds. What do you think the problem is? Does it sound like a fuel supply issue? I have not touched the fuel delivery system? Should I take the fuel pump off and replace the filter? Do I need to suck out the gas tank and start will all new fresh gas? I did add a bottle of heat in case there was some condensation in the tank over the 3yr storage period - inside. Could it be a distributor / points issue?

Any advice?

Re: 1990 Mercruiser 3.0 L Alpha One

Update - I have removed the fuel pump and fuel line - replaced the fuel filter, and cleaned strainer at the inlet to carb - fuel system was clean - nothing specific found. Still no luck starting? Any suggestions?

Re: 1990 Mercruiser 3.0 L Alpha One

Ayuh,.... Try some Fresh gas from a remote tank...

Re: 1990 Mercruiser 3.0 L Alpha One

My points used to corrode in a dry garage after 2 years, even with normal use. I'd start there. If that makes no improvement, drain the entire fuel system and get some new gas in there.

I'd guess the gas in NG, but I'd also guess the points need to be replaced regardless.

Re: 1990 Mercruiser 3.0 L Alpha One

Thanks - I will siphon the gas tank and refill. I have ordered a tube of water detecting paste to confirm whether there is water in the tank or not. I will also try replacing the points.

Do you think I need to remove the carb and clean it as well? There is gas in the fuel line to the carb - and when I spray carb started into the carb it starts long enough to burn what was prayed in - like gas is not getting through the carb?? How difficult is it to remove and clean the carb?

Re: 1990 Mercruiser 3.0 L Alpha One

Thanks. I replaced the points, condenser, rotor. Also checked the gas tank with water finding paste - no water in the tank. I can start the motor and keep it running several minutes if I continuously squirt gas into the top of the carb. But as soon as I stop squirting in gas it quits. Do you think that is because of the old gas in the tank - 3 yrs old... or do you think the carb fuel jets/valves are plugged? As noted earlier I changed out the fuel strainer and filter. Assume there is no problem with the fuel pump itself. I can change out the old gas - but would that keep it from starting - or just cause it to run rough? I am leaning towards removing the carb to clean it up - but am open to advice on what would bethe next best action to take.

Thanks Tim

Re: 1990 Mercruiser 3.0 L Alpha One

New gas plus old crap gas equals old crap gas. Just siphon the all the old fuel out and refill with fresh.

Re: 1990 Mercruiser 3.0 L Alpha One

Finally success!!! I removed the carb yesterday... the orifices were plugged. Cleaned it up, re-installed and it started up and ran like a charm... So even though the gas is a couple years old the motor ran extremely smooth.

SO now I only have one more problem. The wiring connected to the power lift on the stern drive shaft has disintegrated - probably from the sun - wiring insulation has peeled off leaving the bare exposed wire. Where can I find the wiring schematic for the power lift unit?

Re: 1990 Mercruiser 3.0 L Alpha One

Stickies section @ the top of this forum download the service manual for your rig it's free and thank Don S for that there priceless. If the wires aren't to bad use some heat shrink and re seal them.