3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

[Chobes]

Well, here I sit up north with 5 kids wanting to go tubing. Boat ran great for about an hour then it crapped out. Couldn't get over 2000 RPM.

History:
First time on the water this year. last Fall did a full tune-up. Cap Rotor, plugs wires, oil change, gear lube change.
this spring I did the water pump change and filled it with fresh gas!

Today when it bogged out on me, I checked the Gas line and check valve. All Good
Pulled apart Carb and checked filter. All Clear.
Changed Plugs: had a new set of GKN in boat.

Took it back out for a run and Same issue!

Came back in and changed the points. gapped to .022", Ran a little better was able to get on plane but it just sounds like crap coming through the carb. I want to check the timing but I do not have a timing light and limited access to part.

Can you give me anything I can check or do with a set of tools. Or if not where should I start when I get home with it?

Thanks for your time! and Happy 4th!

 

[Radarman68]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

gapped to .022? I am thinking .019 is more like it, at least that is what my Merc 260 calls for. try tightening up your gap a bit unless that is what the manual calls for.

to really get it right, gap it with a dwell meter.

Regarding your engine RPM, does it hit a wall and NEVER go over 2k, or will it creep up slowly past that? if it is a hard wall, so to speak, that would seem to point to ignition, where if it just acts like low power and top RPM varies a bit, then that may be more like fuel.

[on edit, looks like .022 is right but still suggest using a dwell meter to really zero in on it]

 

[thumpar]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Get the timing checked and you will need to check dwell also.

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Ya that is what the SELCO book called for. .022" gap. I will hit it with a dwell when I get home.

It hits a wall and never goes past 2K RPM. The fuel issue worries me. I just filled it up this morning. That would really blow if I had to get rid of 20 gals of gas.

Oh and it is really hard to start. This morning it fired right up when I dropped it in. now I have to throttle it to get it to fire. and when it does it idles pretty rough if at all some times.

 

[thumpar]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Get the right manual too. That Selco will make a nice place to put your knees on and that is about it.

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Get the right manual too. That Selco will make a nice place to put your knees on and that is about it.

Really! That sucks too! I Will find another one. Thanks.

 

[airshot]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

First thing I would check for is water in fuel, hopefully you have a water/fuel seperator. Then you might look at the fuel pump and be sure it is providing the proper pressure. I have bad fuel do just what you describe. Do you have a nice hot (blue not white ) spark? Even though fuel filters are clean there could be dirt (gum from fuel) in the small passages in the carb. Good luck !!

airshot

 

[thumpar]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

The factory manual link can be found in the adults only link at the top of the mercruiser section.

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Ye Don't have a fuel water separator! I will put one on asap!!!!

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Just set the dwell and checked the timing. Timing was off 4 degrees. Set to 6 degrees BTDC and Dwell also was off set to 28 degrees. Boat seems to run pretty good right now. get a little stumble every now and again. But it is in my driveway. Still have to get the water separator. Hopefully drop it in the lake soon and give it another run. Getting a Compression tester tomorrow. What should the compression be? and how long should it hold it?

Thanks for the responses. I will post back compression results tomorrow.

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Got home and tried to start the boat. Crank and crank and nothing. kind of back firing through the Carb.
Compression Results!:
Cyl 1: 100 psi
Cyl 2: 0 psi
Cyl 3: 0 psi
Cyl 4: 115 psi!!!!!!!!!!!!!

When I turn it over with no plugs in it I get a blast of air from all the cylinders including the #2 and #3. Strange. try and measure nothing. Its like when it is pressurized it escapes somewhere.

Now What? Check my valve seats? Pull the head and check pistons?
Any Help?
Thanks all.

 

[Bondo]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Got home and tried to start the boat. Crank and crank and nothing. kind of back firing through the Carb.
Compression Results!:
Cyl 1: 100 psi
Cyl 2: 0 psi
Cyl 3: 0 psi
Cyl 4: 115 psi!!!!!!!!!!!!!

When I turn it over with no plugs in it I get a blast of air from all the cylinders including the #2 and #3. Strange. try and measure nothing. Its like when it is pressurized it escapes somewhere.

Now What? Check my valve seats? Pull the head and check pistons?
Any Help?
Thanks all.

Ayuh,.... The head gasket, 'n possibly the head, 'n block are breached, 'tween cylinders 2, 'n 3,...

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Ayuh,.... The head gasket, 'n possibly the head, 'n block are breached, 'tween cylinders 2, 'n 3,...

Something I can see wit me eyes? going to have to pull the head off awyway ill just get a head gasket kit. hopefully it comes with new valve seals too.

Thanks

 

[Bondo]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

Something I can see wit me eyes? going to have to pull the head off awyway ill just get a head gasket kit. hopefully it comes with new valve seals too.

Thanks

Oh ya, you'll See it,...

When ya get it all Cleaned up, check it with a straight edge at the burn through point,...
If ya can Feel it in the block, or head, that part is Junk, 'n needs a trip to a Machine Shop,...

It'll Never, Ever hold a head gasket,...

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

BAM! Bond-o, You were right again! . I will grab a straight edge from work. Looks like carbon build-up. think head and block will be fine. just clean it up really with a green scouring pad and check for flatness.

Thanks everyone for the help!!! Wish me luck and Happy Boating!!!!

 

[Chobes]

Re: 3.0L Alpha1 Gen1 Runs like crap. Hard getting over 2000 RPM

ALL GOOD!!!! WAHOO.! Dwell steady at 30 degrees up to 1750 RPM so Distributor Lobe is not warn yet. Timing set to 6 degrees BTDC. new head, exhaust, thermostat housing gaskets and new thermostat. purrrrrrrring like a kitten. Thanks all for the help. Ill give her a good shakedown this weekend.