How many times?

[billywhizz]

How many times should my engine turn over before it starts? always starts fine when cold but once out to sea and drifting a wreck or starting after 20/30 mins it turns over between 6 and 10 times before it starts? is this normal for a 25 year old engine? the spark is weak, orange, instead of thick blue, the engine has 150psi on all four pistons ,new cylinder head,runs fine, new leads , points, condensor rotor arm, distributor cap, all set correct. I have 9.2 volts on the+ side of the coil and 7.6 volts on the - side have tried a jump wire from battery + to + side of coil, but made no difference to starting, also have got fuel pipe well away from any heat source, checked for voltage drop between battery and starter post (none) now i am stumped!

 

[Alumarine]

Re: How many times?

Try giving it a bit of throttle when trying to start it.

 

[Bondo]

Re: How many times?

Ayuh,... Is it running Rich,..?? maybe the carb is leaking internally...

 

[billywhizz]

Re: How many times?

The plugs are all a healthy colour no soot or black, it makes no difference if i give it throttle or leave it closed i usually open it up a bit as it turns obviously if i pump it will flood

 

[Fishermark]

Re: How many times?

the spark is weak, orange, instead of thick blue,

There's your answer on why it is hard to start.

Now the question is why is the spark weak? It sounds like you did the basics of the tune up. Is the spark weak on every plug?

 

[Don S]

Re: How many times?

What are we working on here?
Old, new, carbed, fuel injected, OMC, Merc, Volvo 4 cylinder, V8. Lots of room for guessing.

 

[Howard Sterndrive]

Re: How many times?

with a healthy cranking speed of 250 rpm, 6 to 10 revolutions is less than 2 seconds of cranking.
Was it ever any better?

Gotta fix the spark though.
You say you have 9.6V at the coil, but what is the voltage there during cranking?
Should get full B+ during cranking. - the jumper wire test should've been redundant - the crank position on the key switch should already do that.

How's the cranking speed? Maybe the starter is weak, and is drawing the whole electrical system down during cranking..

 

[futz]

Re: How many times?

I agree,always nice to know the year, make,hp of motor and drive.

Disconnect the battery follow the neg. cable to the ground on the block, remove and clean,stud, and block, end connection.

Follow the pos cable, and clean the connections at ever point along the way. Don't forget the starter connection.

Clean battery terminals, and make sure of those connections.

Good battery fully charged?

You are letting this carbed motor idle for 3-4 minutes before you shut off the motor, after running it?

 

[billywhizz]

Re: How many times?

There's your answer on why it is hard to start.

Now the question is why is the spark weak? It sounds like you did the basics of the tune up. Is the spark weak on every plug?

Yep, same on all plugs

 

[billywhizz]

Re: How many times?

with a healthy cranking speed of 250 rpm, 6 to 10 revolutions is less than 2 seconds of cranking.
Was it ever any better?

Gotta fix the spark though.
You say you have 9.6V at the coil, but what is the voltage there during cranking?
Should get full B+ during cranking. - the jumper wire test should've been redundant - the crank position on the key switch should already do that.

How's the cranking speed? Maybe the starter is weak, and is drawing the whole electrical system down during cranking..

Hello, thanks for your reply, how do i check the cranking speed, the battery is new so should be fine , it never seems to crank particularly fast, but i have nothing to compare with, the only time it really wangs over and starts right up is within 5 mins of switching off

 

[cr2k]

Re: How many times?

Also make sure your battery cable is on the bottom of any stack of wired hooked to your battery. If not...bad connection.

 

[jtybt]

Re: How many times?

Time to replace the coil and plug wires. Try looking at the engine at night when it's running and see if you have a light show. Or you can do what some of the real old timers used to do...run your hand along the plug wires looking for leaks.


Except that you replaced everything, I would have said to clean the rotor and cap contacts and replace the capacitor and points.

 

[billywhizz]

Re: How many times?

here is the update, cleaned all terminals and connections from distributor back to battery. checked voltage at coil + when cranking = 12v, checked again when running 10v on + side and 9.6v on the other, connected spark tester, dull orange at all plugs, connected spark tester between coil and distributor cap, dull orange spark, disconected gray wire ,no difference, however if i run wire from batt+ to coil + when engine running noticable difference spark is bigger/longer but still orange. dont go quiet on me fellas.

 

[Don S]

Re: How many times?

dont go quiet on me fellas.

You quit on us! Still not a clue what you have.

You would be amazed at the information here if you would part with what you are working on.

 

[futz]

Re: How many times?

you know what that jumper wire does, don't you? It gives straight power to the coil, and the coil gives power to the dizzy, that gives power to the plugs.

So lets look at whats between the battery and the plugs. You have a wire, to a coil, that puts power to a wire, then to the dizzy, then points? rotor? inside the cap, to a wire, to the plug.

Plugs- the right ones for sure for this mystery motor? Gaped right?

All wires good? Run this boat in pitch black and see where the electric sparks are comming from.

All good contacts in the dizzy including rotor? if you have a rotor? Points clean and gapped right?

The rotor contacts inside the cap good, cap on tight.

Finally the coil, some coils on some boats are grounding out on the block maybe.

What this motor charging from the alternator?

Won't give up on you if you don't give up on us.

 

[CheapboatKev]

Re: How many times?

You quit on us! Still not a clue what you have.

You would be amazed at the information here if you would part with what you are working on.

He has a 1982 Merc 3.7
Also has a few threads that seem to point to the same/related issues as this post.

 

[futz]

Re: How many times?

3.7 sheech. Wish i knew that. That has the alternator kit installed, or runs on the stator, in the center of the motor?

 

[billywhizz]

Re: How many times?

3.7 litre 1982 485, carbed with Alternator, New correct plugs properly gapped, new Battery, new spark plug wires, new points, condensor, rotor, and dist cap, already did the dark test but no sign of any sparks, should i be looking into the ignition key switch? what is the purple wire that i have seen mentioned on other similar posts? even though the spark seems weak once the motor is running it runs well, am i expecting too much for a 25 year old motor to achieve a blue spark?

 

[dr_bowtie]

Re: How many times?

coils go weak..have you tried replacing that yet....?

on the old round type there are 2 types...6v and 12v and mixing them isnt good...

 

[Don S]

Re: How many times?

what is the purple wire that i have seen mentioned on other similar posts?

I think we now know what your starting problem is.
You should have a purple/yellow wire going from the slave solenoid to the coil. This puts full power to the coil for starting, after started, there is a resistor wire in the system that lowers the voltage to the coil to prevent the points from burning up.

In this bulletin is the 488 wiring diagram, have a look.
http://www.boatfix.com/merc/Bullet/84/84_03.pdf

You can test it by just running a jumper wire from the POS terminal on the battery to the + terminal on the coil and try to start it. Bet it starts easier.