Ignition Control Module in 1998 Mercruiser 5.7 tbi/efi

[fotonews]

Hello,

I have twin 1998 mercs 5.7 tbi efi engines, starboard runs perfect but port engine took a dump on me and doesn't want to start.
Initial diagnostic said bad starter, not enough cranking power. Replaced and now don't have fuel pulse at injectors, disconnected fuel rail at carb and shoots plenty of gas.
Need to know if i can swap the Ignition Control Modules to rule in or out source of problem.
Any suggestions greatly appreciated!!

 

[Fun Times]

Yes you typically could on a twin engine boat but you need to be careful about just switching them around due to should there be a major problem/short somewhere causing the issue, you stand a chance of damaging the other ECM as well.....It's rare but it does happen. Do your best to find/test everything you can before the ECM swapping if possible.

Typically if you are getting fuel up to the injectors/throttle body but not coming out of the injectors then it's either a clogged injector/s or the injector pulse width isn't firing due to the ECM is not seeing a signals from one the sensors typically found under the distributor cap.

When you crank the engine over, does the tachometer move to around 3 - 400 RPM?

Engine serial number handy?

 

[fotonews]

Thank you Fun Times for your prompt reply.

Serial # 0L012408, regarding tach moving, I'm not sure I'll check that first thing tomorrow. Also just to make sure/clarify, I'm talking about the Ignition Control Module.
Is it the same as the ECM?mI thought they were 2 different things... please confirm.

 

[fotonews]

I forgot to mention that i don't have spark coming out of the coil. I did swap coils and its good. So the problem could be before... how can i test the plugs going into the coil or what goes before coil that can be tested.

 

[Fun Times]

On this system usually no fuel pulse and no spark go together if you know fuel is getting to the throttle body during crank. So I wasn't really surprised by you mentioning you have no spark too.

You need to ensure you are getting both power and ground up to the ignition and 12 volt system all around the engine components of the engine... Since the starter was just replaced, take the time to ensure all the wiring seems to be connected down by the battery, starter, then up to the top of the engine. Also try wiggling the main wiring harness while cranking as it may have come loose. Check all fuses at the engine...Switch the relays between engines too.

Items 8 and 9 is the starting point for things to go bad once you know you have 12v power getting there. http://www.mercruiserparts.com/Show_...ION+COMPONENTS

# 9 is the weakest component and is before the coil.

Here's your parts catalog for your engine model, http://www.mercruiserparts.com/selec..._nbr=809500+98

Also the gray wire at the rear of the tachometer (gauge) should be disconnected as test as an internally shorted RPM gauge could cause the problem you're experiencing as well.

 

[thumpar]

You might try reading it for codes. I know on mine all it takes is an LED and a jumper wire to get the codes.

 

[fotonews]

Hello Fun Times,

This is what i did today:

Swap IC modules as suggested yesterday.
Now having port engine with good ic module from starboard engine and starboard engine with "bad module".
Cranked port engine, nice pulse at injectors felt like it was going to start but didn't. tried one more time but no more pulse at injectors.
Cranked starboard engine (now with "bad module") and started right away no problem.
My conclusion: apparently nothing wrong with modules, could be a bad ground somewhere in port engine??
Where do i go from here...

 

[thumpar]

It could be a bad sensor also.

 

[fotonews]

Thumpar, you mention reading for codes... can i get codes if i can't start engine?

 

[Fun Times]

Can i get codes if i can't start engine?

Yes as long as the ignition key is on and the ECM is powering up properly. Somewhere here on iboats there's detailed guide at how to use a 12v light bulb connected to the data wiring harness connector to read code numbers. Here's a quick video of it working. https://www.youtube.com/watch?v=s2GEO-dlbIg

Did you try disconnecting the gray wire? Any RPM movement at crank?

You had fuel pulse spray but it came to a stop. You seem to be losing your ignition control reference signal somewhere. There's some tests and explanations for this in the service manual that you may have to run through to narrow something down. Do you have? or have you located your service manual online yet?

As for testing the ECM, the safest swap test should be to put the non starting ECM onto the good starting engine and see what happens.

 

[fotonews]

Gentlemen, this is what happened today:

Disconnected gray wire from tach and nothing (no start).
There is no rpm gauge movement when cranking
Voltage @ purple wire @ coil when cranking: 10.25

Service Manual #24

Ignition System Check

Step #7
Voltage 12.28

Step #8
Voltage 12v

Plugged Rinda CodeMate and no error codes.

Step #5 says to check for secondary spark... what does that mean?????

Help please

 

[thumpar]

From the Oracle. http://forums.iboats.com/forum/engi...ives/51341-efi-code-timing-tool-make-for-1-00

I have done it. This is my video. https://www.youtube.com/watch?v=s2GEO-dlbIg

 

[fotonews]

Will the engine start if good spark, good fuel pressure and all around compression @ 95psi?

 

[thumpar]

95psi seems a little low. Have you used another gauge? It should still start but it is tired.

 

[fotonews]

Those readings were done with a bad starter, i replaced it, now should be higher but for some reason i can't get the sucker to start, even with a bit of starting fluid. I have good spark and plenty of fuel delivery. Im at a loss. New sparks, checked all wires for spark, good coil, ignition module tested ok.

 

[thumpar]

Does it sputter at all or backfire?

 

[fotonews]

It sputter a bit but no backfire

 

[fotonews]

Finally got engine running after changing the pick up coil, but it runs very rough and a lot of white smoke coming out of valve cover breather hose connected to flame arrestor. Any ideas whats causing the smoke??

 

[thumpar]

What are the compression numbers across all cylinders? You could also do a leakdown test.