Engine cranks but won't fire, Update as of 6/11, Now No spark with new ICM - not the usual culprits

[littlebuzz]

Engine cranks but won't fire, Update as of 6/11, Now No spark with new ICM - not the usual culprits

Motor is a 2000 Mercuiser 3.0L (181CID), serial #0L650308
Electronic ignition
Mechanical fuel pump
New distributor cap, rotor, plugs, plug wires, and coil
Sterndrive Alpha 1, serial #0M559906

Boat was new to me last year.
Previous owner(s) removed kill switch.
Motor was running, but very rough. During winterizing, I pulled the carb to rebuild it over the winter.
Carb had rust in the float bowl and power value was frozen in place. Fuel tank was drained during winterizing and a water separator was added.

Bought carb rebuild kit, brass float, and a 2nd carb to use for parts since float bowl was in such bad shape.
Rebuilt carb and reinstalled beginning of May.
I smelled fuel and noticed excessive amount of gas in venturi.
Removed carb and readjusted float. This was tricky since all documentation was for the Nitrophyl float.
Put it all back together and it still won't start.

Engine cranks but won't fire.
Fuel does spray when throttle lever is thrown forward.
Starting spray will make it fire a little but it still won't start.
12v present at pos side of coil with key "On".

Tanks in advance,
-Buzz

 

[Fun Times]

Hi there, Sounds like you'll want to check the consistency of spark coming out of the coil going to the distributor cap.

You'll also want to check & change the fuel filter located at the fuel pump...Item number 2, http://www.mercruiserparts.com/Show...=4893&bnbr=100&bdesc=Fuel+Pump+and+Carburetor

Also try performing an engine compression test so you know the engines internal condition.

 

[littlebuzz]

Thanks Fun Times.
I installed a new fuel pump filter last fall. Is that good enough?
I'll have to borrow a compression guage. But I'll pick that up and test the cylinders tomorrow afternoon.

 

[Bondo]

I installed a new fuel pump filter last fall. Is that good enough?

Ayuh,.... Welcome Aboard,.... Filters are only good, til the next slug of water, 'n crud comes by,....

Yer Diagnosin' a problem, so start with the easy stuff 1st,...... Like the fuel filter,.... more specifically, the Contents of the filter,.....

 

[littlebuzz]

Thanks.

Compression test results:
1 - 115
2 - 130
3 - 130
4 - 120

Pulled the fuel filter. Fuel in bowl looked clean. Didn't see any particulate matter.
I don't like the looks of the filter though... in fact I remember not being too impressed when I received it in the mail.
Think I'll pick up a new one at West Marine tomorrow.

 

[alldodge]

Motor is a 2000 Mercuiser 3.0L (181CID), serial #0L650308
Electronic ignition
Mechanical fuel pump
New distributor cap, rotor, plugs, plug wires, and coil
Sterndrive Alpha 1, serial #0M559906

Boat was new to me last year.
Previous owner(s) removed kill switch.
Motor was running, but very rough. During winterizing, I pulled the carb to rebuild it over the winter.
Carb had rust in the float bowl and power value was frozen in place. Fuel tank was drained during winterizing and a water separator was added.

Bought carb rebuild kit, brass float, and a 2nd carb to use for parts since float bowl was in such bad shape.
Rebuilt carb and reinstalled beginning of May.
I smelled fuel and noticed excessive amount of gas in venturi.
Removed carb and readjusted float. This was tricky since all documentation was for the Nitrophyl float.
Put it all back together and it still won't start.

Engine cranks but won't fire.
Fuel does spray when throttle lever is thrown forward.
Starting spray will make it fire a little but it still won't start.
12v present at pos side of coil with key "On".

Tanks in advance,
-Buzz

:welcome: to iboats Buzz

Have a look at the link below, it is a bulletin and also has testing/troubleshooting guides for your EST ignition system

 

[littlebuzz]

Do you mean the link in your signature?
That's about fuel pump maintenance. I didn't see anything about troubleshooting guides.
Although now I'm going to check my crankcase oil for gasoline.

BTW - is it possible to replace the mechanical fuel pump with an electric one?

 

[alldodge]

Do you mean the link in your signature?
That's about fuel pump maintenance. I didn't see anything about troubleshooting guides.
Although now I'm going to check my crankcase oil for gasoline.

BTW - is it possible to replace the mechanical fuel pump with an electric one?

Sorry looks like the link didn't make it
http://www.boatfix.com/merc/bullet/90/90_15.pdf

Yes, you can replace a mechanical with and electric fuel pump

 

[littlebuzz]

I have replaced the fuel pump filter and checked the fuel pump pressure which reads about 6psi.
Checked the crankcase oil and found noting but clean motor oil.
Checked spark plug gaps.
Checked the gray tach lead for a short and found none.
I noticed the Black-to-Brown connection for the Trim Sender was disconnected. I reconnected that.

What about the white/green wire coming out of the distributor? I followed it up to the Shift Interrupt Switch where I was able to gain access by disconnecting the bullet connector.
I read somewhere that with the key in the "Run" position it should read 12v... I get 3.3v.
Does that mean my ICM is bad?

 

[alldodge]

I have replaced the fuel pump filter and checked the fuel pump pressure which reads about 6psi.
Checked the crankcase oil and found noting but clean motor oil.
Checked spark plug gaps.
Checked the gray tach lead for a short and found none.
I noticed the Black-to-Brown connection for the Trim Sender was disconnected. I reconnected that.

What about the white/green wire coming out of the distributor? I followed it up to the Shift Interrupt Switch where I was able to gain access by disconnecting the bullet connector.
I read somewhere that with the key in the "Run" position it should read 12v... I get 3.3v.
Does that mean my ICM is bad?

The reading of the white/green voltage is of no issue. That wire(s) is used to put engine in base timing mode to set timing. It actually goes is grounded when in timing mode and is grounded by the interrupter switch when shifting out of gear.

The gray wire goes to the tach and if it is grounding out buy the wire or by the tach it self. Best way to determine if it is grounding is to remove it from the negative terminal of the coil.

 

[littlebuzz]

Alright then, gray wire disconnected from coil. No difference.

I have a Lisle spark tester like this.

It glows a dull shade of pink/orange on each cylinder. Shouldn't it be bright white or blue?

 

[alldodge]

This does not add up. You need fuel, spark and air to make an engine go bang, either in the cylinder or backfire through the carb.

You said

Fuel does spray when throttle lever is thrown forward.

and spark is

It glows a dull shade of pink/orange on each cylinder

Even with a dull spark there should be something happening

So unless your gas has gone bad there should be something. Put a small amount of fresh gas the throat of the carb and see if it will fire

 

[littlebuzz]

Gas is clean and fresh.
Added a tablespoon in the throat... no fire.

I really don't know, but I think the weak spark might have something to do with it. I watched a video of a spark test light in action and it flashed like lightning. When I test, I get a barely noticeable pink glow.

Finally got hold of a manual. Mercruiser Service Manual #26. When I get home at 3pm, I will run through the ignition troubleshooting chart on pages 56-59.

 

[alldodge]

Sure sounding more like spark then fuel. Look forward to hearing results of your testing

 

[muskyfins]

I understand this is an electronic ignition system, but I have had weak spark on conventional ignition systems that wouldn't ignite fuel enough to start the engine. FWIW.

 

[littlebuzz]

Thanks muskyfins. That's the what I think is going on here.

Yesterday afternoon I began to run through the troubleshooting flowchart from Service Manual #26. I reached the bottom of page 1C-12 (p58 of the PDF file) and stopped because I didn't have a test light. Reading ahead at this stage, it seems the problem will be the ignition coil, the pickup coil, or the ignition control module.

An earlier test showed the pickup coil to be OK.
The ignition coil is new.
So that leaves the ICM.

I'm getting a test light today and will complete the diagnostics.

 

[alldodge]

Getting it narrowed down is the only way to go, thanks for updating

 

[littlebuzz]

No spark - not the usual culprits

Background:
Boat is a 2000 Sea-Pro. Kill switch was either removed or shifter was replaced with earlier version.
Mercuiser 3.0L (181CID), serial #0L650308
Electronic ignition
Mechanical fuel pump
Sterndrive Alpha 1, serial #0M559906

The engine cranks but doesn't fire. I used a spark tester to check the spark and it would only glow a dim shade of orange/pink. I thought I'd start by taking care of the obvious and replace the distributor cap, rotor, plugs, and plug wires. The existing ones looked well used. Still just a weak spark. I put the spark tester on the coil and got the same dull pink glow. Foolishly I assumed that meant the coil had to be bad so I ordered a new one from Rockauto. But still the engine wouldn't fire. Then I got a hold of the Service Manual and found the troubleshooting section.

Following the steps in the Ignition System Check flowchart of the Troubleshooting section of Service Manual #26, I worked my way down to Step 5 and the measurement showed No Drop in voltage. As instructed I checked the ground on the Ignition Control Module (ICM) and since it was shiny metal against shiny metal it looked good to me. Which means I need to replace the ICM. Well I did. And now I get no spark at all. Not even that dull pink glow. Nothing.

Is it possible the problem is in the console? A coroaded wire or bad gauge? Something shorting to ground?
I'm scratching my head so much I'm going bald.

For now I will start again at the beginning of that flowchart. Maybe something has changed.

 

[Bondo]

Ayuh,..... Do you have 12v power to the coil's (+) terminal, with the key in the On position,..??

 

[figaro]

is it equipped with a tach ? try disconnecting it , it may possibly be shorted in turn pulling the coil trigger line down