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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 8499
Experience:  39 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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i HAVE A 1985 STARCRAFT WITH A MERCRUISER 3.0 WITH ALPHA 1.

Customer Question

i HAVE A 1985 STARCRAFT WITH A MERCRUISER 3.0 WITH ALPHA 1. FIRST I TOOK OFF MY LOWER UNIT IN SOME SHALLOW WATER REPLACED IT,THEN STARTED RUNNING SO BAD THAT IT QUIT.COME TO FINE OUT CAM WAS BAD,I PUT IN NEW CAM,LIFTERS,CAM GEAR,AJUSTED LIFTERS TO ZERO AND ONE TURN MORE,TIMMING MARKS ARE RIGHT ON IS NOT 180 OFF ROTOR IS POINTING ON # XXXXX AT 22.GOOD COM 150,NO POWER AT ALL IDLES ROUGH KEEPS QUITTING.I OWN A AUTOMOTIVE REPAIR SHOP IN UP STATE NY AND IVE WORED ON ALL KINDS OF MOTORS INCLUDING BOATS AND HAVE NEVER SEEN ANYTHING LIKE THIS BEFORE AND THE PLUGS ARE BLACK.WHEN YOU PUT A TIMMING LIGHT TO IT YOU CANT EVEN FINE THE TIMMING MARK ON CRANK,AND I PUT IN CAP,ROTOR AND WIRES,POINTS AND COND NEW LAST FALL.RAN GOOD IT SEEMS TILL I HIT ROCKS HELP THANKS ANDY.
Submitted: 4 years ago.
Category: Boat
Expert:  James replied 4 years ago.

Hello, welcome to JustAnswer.

 

With no timing marks showing, you either have the distributor in wrong, and it sounds like that has been considered and checked, or you didn't get the cam to crank timing correct.

Do you have an adjustable timing light you can use? One that allows you to advance when the light flashes? If so, use it to get the mark to show up where it's supposed to be and then read the advance dial to see how far off it is.

Otherwise, pull the cover and check the timing marks on the cam and crank gears for alignment.

Customer: replied 4 years ago.
Hi Jim,what i foregot to tell you is last wk put in water two passes across lake ran great then lost power dist had turned,turned it back it started was missing on two cylenders held it wide open cleared up ran good again,then lost power again quit and wouldent turn over got home pulled dist to ck gear on dist and found out 2 screws had fallen out of vacume advance.cam and crank marks on the money dist rotor on #1 with comp stroke up and still runs poor,and no i have a regular timming light as with todays cars we set timming with a scanner.this one will be a tough one for you Andy.
Expert:  James replied 4 years ago.
For starters, you have the wrong distributor on that motor. There is no vacuum advance on Mercruiser marine engines. The advance is set on a curve. You are going to need to put a marine distributor on that motor.
Customer: replied 4 years ago.
Hi Jim, it is a marine distributor theres no vacuum to it im just relateting it to a cars distributor i also know you cant interchange marine and car parts as marine parts are built stronger then car parts all parts came from rome marina cam,lifters,gears,dist,and gaskets.As i said before timming marks are right on,rotor is on # XXXXX and im not 180 off with dist.This is what makes it so hard to understand.Ive also had my father in law look at it to and hes worked on boat motors and car motors for over 40yrs and a buddy of mine also looked at it and he also has a lot of yrs with boat motors Andy.
Expert:  James replied 4 years ago.

Well, you are going to need a timing light to set your timing on this one.

We also need a fuel pressure reading, compression check, and to check to make sure spark is still there. Check the coil primary resistance and secondary resistance. What are the readings?

Which distributor do you have? What is the point gap set at? Where is the dwell set? Where are you setting the timing?

Customer: replied 4 years ago.
Jim,allready told you if your reading my answers comp 150,have timming light but not with dial setting,points at 22 have spark on all 4 cylenders,fuel pressure is 3.5 about a pint in about 20-25 seconds at an idle.3.2 volts on condensor.you cant get a reading on the timming because you cant see the mark on crank when its running but before it started acting up it was set at 8 degress andy.
Expert:  James replied 4 years ago.

Ok, the timing should be set a 4 degrees BTDC, But that's not an issue now.

There is just no way for your timing marks to be that far off with the engine running unless you have the timing light hooked to the wrong spark plug wire, the distributor is not installed correctly, the valve timing is off, or you sheared off the key on the harmonic balancer.

Customer: replied 4 years ago.
Jim,timming light is hooked up to #1 cylender,and like i said before dist is installed right and both timming marks were right on with #1 cylender up on comp stroke and key way is okay.Ive been an automobile machanic for 35yrs i know how to run a timming light there the same as a car engine.that is whats got me puzzled Andy.
Expert:  James replied 4 years ago.

I didn't mean to imply you lacked the know how, Andy, It's obvious you know what you are doing. My apologies if it sounded that way.

Check the harmonic balancer. If everything else is all right, the outer ring of the balancer must have shifted on the inner hub. That would explain the engines not running well, too.



Edited by James on 7/24/2010 at 2:20 PM EST
Customer: replied 4 years ago.
Jim,outter ring is good,I know that on gm cars the outter ring can slip around on the inner hub and therefore you wouldnt be able to see the mark.If you was here you wouldnt beleave it unless you saw it with your own eyes.and im sorry for snapping at you but ive been on this boat for a wk and its drove me nuts and if the timming has to be at 4 degrees it would run rough and if you cant make that up by turning the dist one way or another you could pull it out and take it one tooth one way or another and make it up Andy.
Expert:  James replied 4 years ago.
I am as baffled as you are at this point. I am going to opt out and give another expert the opportunity to help you. I am just out of idea's
Expert:  Tan replied 4 years ago.
Hi, I've read all your input and I did not see where you physically checked TDC by removing the spark plug and using a pencil or other object to find TDC you should have timing marks aligned and distributor at # XXXXX If not I think you know what that means.
Customer: replied 4 years ago.
Hi Tan,after i emailed Jim the last time we did physically ck TDC i pulled the valve cover and # XXXXX spark plug to see that i was on comp stroke and i am and the rotor is pointed at # XXXXX on the cap, i guess im going to have to take it somewhere to see if they can fined out whats going on with it thanks Andy.
Expert:  Tan replied 4 years ago.
OK Andy, Good luck

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Tan
Tan
Marine Mechanic
8499 Satisfied Customers
39 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.