Mercruiser 3.0 cranks but wont start

I have a 88 Glasstream with a 3.0 mercruiser I/O. After de-winterizing last year (2012) it would crank but not start,no fire from coil at all.I bought a new coil and nothing, After about a week of working on it I took it to the repair shop.The next day they had it fixed,replaced the coil they said and it started,i chalked it up to a bad coil that I had bought and paid them $175 repair bill.It ran fine all last year.This year I had the same problem...cranks but no fire from the coil.So i got a new coil again...nothing again.I cleaned connections etc...nothing. Switch looks aftermarket so i flicked it several times back and forth on/off and it started. Took to the lake that day and found the lower impeller bad..all that cranking i guess!After I replaced the impeller then no fire again! New switch,clean connections again etc...nothing,so I ran a wire that bypassed shift switch and it started and ran fine for a couple weeks. Now... after sitting covered for about 2 weeks I'm back to the same problem again! I'm guessing it's got to be a corrosion problem somewhere or maybe its the shifter switch,but when its in gear it wont crank at all so...?Any help would be appreciated,very frustrating at this point! Thanks

Re: Mercruiser 3.0 cranks but wont start

Is there 12v at the coil?
Is there spark?
Bad tach kills spark.
No motor should be able to crank in gear, neutral only.

Re: Mercruiser 3.0 cranks but wont start

Put some new points and condenser in it, then you will have spark.

Re: Mercruiser 3.0 cranks but wont start

Yes I have 12v at the coil but Nothing from the coil tower once it starts cranking, so no fire going to the points and condenser yet. I have tried disconnecting the gray tach wire from the coil without success. I think the not being started for awhile is a clue but I'm not sure.

Re: Mercruiser 3.0 cranks but wont start

Why does everybody think coil? Look at it this way: condensers almost never fail, coils seldom fail, distributor grounds sometime fail and points fail all the time. So look to the points first.

Re: Mercruiser 3.0 cranks but wont start

jrooster said:

Yes I have 12v at the coil but Nothing from the coil tower once it starts cranking, so no fire going to the points and condenser yet. I have tried disconnecting the gray tach wire from the coil without success. I think the not being started for awhile is a clue but I'm not sure.

Click to expand...

Dude, the points are what makes the spark, opening and closing. Not just by sight but electrically. They get glazed over and look like they are working, but they never make contact.

REPLACE THEM, they don't last as long as spark plugs do.

Re: Mercruiser 3.0 cranks but wont start

jrooster said:

Yes I have 12v at the coil but Nothing from the coil tower once it starts cranking, so no fire going to the points and condenser yet. I have tried disconnecting the gray tach wire from the coil without success. I think the not being started for awhile is a clue but I'm not sure.

Click to expand...

Ayuh,.... There's a real Good write up, up in the Adults Only section that explains Points Ignition,...

Ya oughta read it, as ya don't understand how yer ignition works,...