96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

[bcox777]

Forum Members,
I have a 1996 Maxum with a mercruiser 4.3 LX Gen + (thunderbolt ignition) and have been experiencing some stalling issues at strange times.

I get the boat out on the water and can be cruising along and the engine will just stop as if I turned off the engine at cruising RPMs. This usually happens for the first time about 20 - 30 minutes after being on the water but then seems to happen more frequently after the first occurrence.

My last time out I did notice a few more details if I am cruising along and bring the throttle down abruptly, the engine is more likely to stall. Also, when the engine stalls, the RPMs drop dramatically and seem like the engine is trying continue running prior to completely cutting out. After cutting out, the engine fires right back up and continues to run strong until the next stall which ranges from 10 - 30 minutes and happens at varying levels of RPM.

At first I thought this was a fuel problem so I changed the water / fuel separator filter, checked the screen where the fuel line connects to the carburetor and all looks good. I have been through several tanks of fuel this season so this should also not be a problem.

Any suggestions on how to further troubleshoot to prevent future stalling episodes? Please help.....

 

[Don S]

Re: 96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

Check the connectors for the ignition module. If they get corroded, they cause exactly that problem.

 

[bcox777]

Re: 96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

Don,
Thanks for the reply. I pulled off what I think to be the Ignition Module and there did not appear to be any corrosion on the harness or on the module itself. The part I inspected was mounted to the back of the distributor and had the following part numbers on it. 807829 - 1 and under that sticker it listed 4.3LX / LXH Alpha. On the part itself it has Manufacturer "Nippondenso" with the following part numbers 131300 - 2360 and T4398A 6.11. The harness is a 8 way connector and the part itself has 8 male prongs and all of which appeared to be free of corrosion.

Assuming I inspected the correct part. 1) is there a way to test the module? 2) is there some kind of conductivity spray I can coat the connections with? 3) could the module need to be replaced?

Is there another part I should be inspecting or replacing? Maybe the coil or the distributor cap? Any other suggestions on the ignition system?

Thanks Again for your help.
Brian

 

[bcox777]

Re: 96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

Don / Forum Members,
I cant seem to figure this one out... Since the Boat was not stalling until it was good am warm I thought the issue may be heat related so I replaced the coil. Additionally, I replaced the distributor cap and rotor and also replaced the plugs. Went out yesterday and experienced the same problems......

Still dont think its fuel related since there are no problems starting or cruising for a while.

Please help............

 

[dsmmace]

Re: 96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

Put a fuel pressure gauge on it and have someone drive while you watch the fuel pressure gauge, if it looses fuel pressure then you can at least narrow it down to the wiring, oil pressure switch or the fuel pump.

 

[bcox777]

Re: 96 Mercruiser 4.3 LX Stalling at various RPM levels and while cruising

Thanks dmmace.

Do you know where I connect the pressure test gauge to on this engine? I looked over the fuel system and did not see any points where I can connect to monitor the pressure:confused.

Also, I took the boat out again this weekend and found that if I am frequently stopping and starting or fluxuate the throttle while towing a tube or wake board I do not experience the issue outlined above. Not sure if this helps but just another piece of info that I came off the water with this week. It really only happens when I am trying to get from point A to B without stopping. Again, thanks for your help.