Monsoon 320 bog, surge, die only after warm.. PLEASE HELP,

[justgary]

24 minutes ago, TreyF14 said:

It’s been several years since any of you posted on this thread but... I have a 1997 malibu sunsetter with the monsoon 320. I am currently having the same bogging symptoms listed above. I have replaced the ecm, cap and rotor, spark plugs, fuel filters and fuel pumps, map sensor, fuel lines. And I’m still getting a bogging. I’m stuck and have no idea what to do. ANY info would be greatly appreciated. 

Buy a fuel pressure gauge and test the pressure at key on/engine off, idle, midrange, and wide open throttle.

Since you have changed everything but the plug wires, consider doing that if the fuel pressure is OK at all of the test points.

[BlindSquirrel]

What about your injectors? They have small filters in them, not too difficult to check. Might be time for a full rebuild. It's only like $200 to have them all rebuilt.

 

[Bozboat]

The problem is likely either fuel related or ignition related.  If you have good fuel pressure as explained above then the next time is dies, place your hand on the distributor to see if it is hot. The ignition control module is under the rotor  inside the distributor cap.   You could also verify this as an electrical problem by checking the spark by pulling a plug wire and holding it near the block when cranking the engine. No spark would indicate a bad ICM or coil.  

 An ICM will get hot and cut off  when it begins to fail and work again when it cools off.   When this starts to happen it will fail sooner than later and you will be paddling. 
 

if you have a safety lanyard of the older design where the plastic clip holds the red button pressed in to run, that plastic clip can fail just enough to toggle the red button which shuts off the engine.  The newer design has a plastic clip that holds the red button out.  

[TreyF14]

I was wrong. I only did the distributor cap. My next step will be the ignition control Module! 

[justgary]

11 minutes ago, TreyF14 said:

I was wrong. I only did the distributor cap. My next step will be the ignition control Module! 

Test the fuel pressure....

[TreyF14]

Fuel pressure is good. ICM is changed. Getting spark. Haven’t thought about the injectors.. I’m gonna say that’s probably my next step

[dtm8119]

Does it just bog out of the hole or is it at any time you punch it when at a given speed?

What's the max rpm's you can get out of it at WOT?

[Jpandson515s]

Hello it's been awhile since this post originally posted but I was hoping someone could help me out. I have a 1996 malibu sunsetter vlx with the 320 monsoon efi with 662 original hours. Took it it out yesterday and it started fine idled fine. But couldn't get over 1900 rpms. Noticed a leak at the back of raw water pump at the rear seal... I recently did a tune up new fuel filters new fuel pump new spark plugs and wires. New distributor cap and rotor. New impeller. New water pump new thermostat. Changed the oil and filter. Drained all the fuel completely aka Took tank out of boat. I am at a loss. Really hoping for a simple fix. Any info at all is much appreciated.

 

[formulaben]

Did you change the spark plug wires one at a time?

[Jpandson515s]

On 7/19/2022 at 10:31 AM, formulaben said:

Did you change the spark plug wires one at a time?

Yes sir I changed the spark plugs one at a time. Runs like a champ at idle and runs like a champ for about 9 min then boggs down and will backfire if you keep the throttle down.  If I let it sit for 10 minutes it will run like a champ again for about 9 minutes. At idle and in neutral you would never know there was a problem it revs fine.

[Rednucleus]

Sounds like not getting enough fuel.  You changed the pump; does it have a pressure regulator?  Also, loosen you gas cap when the problem starts to see if your tank is not venting properly.

Edited February 21, 2023 by Rednucleus

[Jpandson515s]

Hi I've done everything they've said to do and it's still not working local dealership thinks it's the ECM should I just go ahead and buy one and try it Out still cheaper than a new boat

[Bozboat]

before replacing the ECM, Send the fuel injectors off to get rebuilt, replace the Ignition Control Module. 

 

[justgary]

3 hours ago, Jpandson515s said:

I've done everything they've said to do

Who is "they?"  You have gotten good advice from @Rednucleus, but didn't come back to tell if you did anything.  I would not buy an ECM without knowing it is bad.

Check the fuel pressure at key on, idle, and wide open throttle.  It should be a constant ~42 PSI.  Also check it when the engine bogs down.  The test port schrader is on the fuel rail on the top of the engine.

Does the temperature stay under 160*F?

@Bozboat suggests an ICM; that is probably a decent idea as well if the fuel pressure is OK.

Please confirm that your engine is multiport injected rather than throttle body injected.

[Bozboat]

On 2/20/2023 at 6:28 PM, justgary said:

Who is "they?"  You have gotten good advice from @Rednucleus, but didn't come back to tell if you did anything.  I would not buy an ECM without knowing it is bad.

Check the fuel pressure at key on, idle, and wide open throttle.  It should be a constant ~42 PSI.  Also check it when the engine bogs down.  The test port schrader is on the fuel rail on the top of the engine.

Does the temperature stay under 160*F?

@Bozboat suggests an ICM; that is probably a decent idea as well if the fuel pressure is OK.

Please confirm that your engine is multiport injected rather than throttle body injected.

also consider sending the ECM to OBD DIAGNOSTICS for testing or repair before replacing it.