357 indmar with ECM problems

[Chuck2627]

Is it advisable to change from an ECM ignition to a real carburetor on a 1997 Malibu lx response? Seems as if the ECM computer control are difficult to find.

[justgary]

Are you sure that your ECM is bad?  Is your engine multiport or throttle body injected?  What are the symptoms that you would like to fix?

[Chuck2627]

Plugs get fouled after 1-2 hrs. Too much fuel. I and others just replaced parts and sensors. Boat dealer couldn’t find any other problems or failures.  With new / clean plugs runs great for 1/2 hour.. then gets flooded. Been stranded several times a year. ( throttle body rails). Sometimes idling too high, sometimes a 8-900 ( fine). Dealer suggested switching to regular carburetor, and said ECM no longer available. ECM replaced 4 yrs ago. Gas problems seemed to start after that. Seems throttle not properly being controlled.

basic question, Is it worthwhile switching to carbonation system?

[csleaver]

High fuel pressure and faulty engine coolant temperature sensor (ECT) or throttle position sensor (TPS) values are a common cause of spark plug fouling on fuel injected engines.

[justgary]

1 hour ago, Chuck2627 said:

basic question, Is it worthwhile switching to carbonation system?

New intake manifold, new carb, new distributor.

Or just fix the problem.  It is probably not the ECM.

I would add bad plug wires and dirty injectors (hung open) to @csleaver's list.

Reading the MEFI data should point you quickly to the problem, and I'm really shocked that the dealer can't fix it quickly.

[Chuck2627]

Dealer ( 75 miles away) says ECM replacements are no longer  available.  Plug wires replaced twice ( since. Easy and inexpensive). Would all injectors go bad at same time? The fouling seems uniform on all cylinders?  Engine does run a little cool ( boat has a heater - but not used in summer. )
Basic question, Will it run well after conversion to carburetor system?  On one side, a carburetor system allows adjustments, where the ECM requires expensive testing tools. I,m 80 yrs old and am not going to buy a $50,000 boat. I just would like this boat to be dependable for a few more years.  Don’t like getting stuck in middle of lake and have to be towed back to my dock. Also uncomfortable with towing boat on  interstate hwy.  

basic question. Is conversion to carburetor system a satisfactory solution? 

[electricjohn]

If TBI, one stuck injector could cause your problems.

[justgary]

38 minutes ago, Chuck2627 said:

Dealer ( 75 miles away) says ECM replacements are no longer  available.  Plug wires replaced twice ( since. Easy and inexpensive). Would all injectors go bad at same time? The fouling seems uniform on all cylinders?  Engine does run a little cool ( boat has a heater - but not used in summer. )
Basic question, Will it run well after conversion to carburetor system?  On one side, a carburetor system allows adjustments, where the ECM requires expensive testing tools. I,m 80 yrs old and am not going to buy a $50,000 boat. I just would like this boat to be dependable for a few more years.  Don’t like getting stuck in middle of lake and have to be towed back to my dock. Also uncomfortable with towing boat on  interstate hwy.  

basic question. Is conversion to carburetor system a satisfactory solution? 

You seem very stuck on the carb idea even though it is not a great solution.  Would it work?  Yes.  For less than the cost of just your new distributor you could get a diagnostic tool and read your engine data.  If you enjoy DIY, you can build a harness and read engine data for about $40.  We keep prodding you to forget the carb idea and fix your existing engine.  It is very unlikely that the ECM is the issue.  You will enjoy your injected engine after repair a lot more than a carbed version of it.

I would do the following.  If your dealer already did them, great.  Let us know.

• Compression/leakdown test to verify engine mechanical condition.
• Fuel pressure test at key on, idle, and wide open throttle.
• Verify base spark timing.
• I assume that with new plug wires you also have new cap and rotor.  If not, change them.
• Send injectors out for cleaning/patterning.
• Read engine data to see what the temperature and injector pulse width are doing.

The very thought that your dealer suggested a carb is a great reason to run away from them and find a decent mechanic who knows what is going on.  If you will let us, we can help you fix it.  We still don't know if you have port or throttle body injection.  Roughly how many hours are on the engine?

Please post a photo of your engine. 

[Rednucleus]

I would expect modifying it vs fix it right will also adverely affect resale value

[mikeo]

You can pull the ECM and send it in to have it tested (and programmed/reprogrammed) if necessary: http://mefiburn.com/

I had 2x ECMs get fried due to a bad solar controller charging starting batteries on a houseboat. I sent the 2x ECMs in, they bench tested them (DOA), and were able to put the correct program in matching used units they had*, then ship them back to me within the same week.

*The units I received were used from a different engine, but were programmed for my engine, and it fired right up as soon as I plugged them in.

If you think the ECM is bad, call MEFIBurn/OBD Diagnostics, Inc. to discuss the symptoms with them

Someone suggested in another thread that it's possible to put injectors in Hoppes solvent in an ultrasonic cleaner to do some R&R on them yourself. If it's a heated ultrasonic cleaner, that might be a fire risk. Someone else suggested that injectors are readily available if you tell the auto parts store the engine is from a '99 Chevy Tahoe (or similar), but check the parts interchange with what you have.

[JasonK]

I'd be worried that if you change to a carb, the boat still wouldn't run right. 

Get a second opinion on the ECM being bad. If it's bad, and can't be repaired, then a carb setup might be worth it.

[Woodski]

On 3/15/2024 at 10:02 PM, Chuck2627 said:

Plugs get fouled after 1-2 hrs. Too much fuel. I and others just replaced parts and sensors. Boat dealer couldn’t find any other problems or failures.  With new / clean plugs runs great for 1/2 hour.. then gets flooded. Been stranded several times a year. ( throttle body rails). Sometimes idling too high, sometimes a 8-900 ( fine). Dealer suggested switching to regular carburetor, and said ECM no longer available. ECM replaced 4 yrs ago. Gas problems seemed to start after that. Seems throttle not properly being controlled.

basic question, Is it worthwhile switching to carbonation system?

Did the dealer that can't locate the current problem do the ECM swap?  Might be as simple as getting proper troubleshooting to solve the problem if the current dealer does not have the capability.  You might consider a direct call to Malibu (to the engineering department) for some assistance.  As noted there are some sources outside the dealer network that have ECM diagnostic capability.  A buddies LXI has overfueling which turned out to be leaky injectors.  Good luck.  To your question - yes you could retrofit a carb although it will be more than just a carb install and carbs do require maintenance.  A carb will reduce the desirability of the boat as FI is considered 'better' and desirable.