99 4.3 Mercruiser stalling

[timmyjane]

Ok here goes. Hopefully someone can help me with this stalling issue.

New boat to me.
Will run great for the first 20mins or so and then it begins.
Doesnt matter what the rpms are.
Once it begins it happens very frequently. Ever 30 seconds or so. If it sits for a few minutes between stalls i can maybe get 60 seconds out of it before it starts back. During this time I can idle or run WOT.
Starts right back up after the stall.
No issues cold starting.
Sometimes it diesels.


Recent maintenance.
New shift cables installed at the dealer.

Since the stalling began I have:
Changed plugs
Changed coil
Rebuilt carb completely.
Changed fuel filter.

Thanks for any guidance anyone can provide.

 

[Don S]

Re: 99 4.3 Mercruiser stalling

I can see a number of things causing this, so lets start knocking them off.
#1 on my list would be the oil pressure switch that controls the fuel pump.. Down on the port side of the block just above the oil filter housing is the switch. Are the terminals clean and shiny or rusty? If rusty, that very well could be your problem. If not, get a jumper wire and jump the two wires (purple, and a purple yellow) together and see if it keeps running.

 

[timmyjane]

Re: 99 4.3 Mercruiser stalling

Thanks Don.

Id say shiny.

Since I'm not on the water now could I check the resistance of this to test?

 

[Don S]

Re: 99 4.3 Mercruiser stalling

Then make yourself a short jumper to go between the two wires and see if it works. The switch could be bad internally.

 

[timmyjane]

Re: 99 4.3 Mercruiser stalling

Well I guess thats it. I got it to stall several times and then made the jumper, no stall. Disconnected the jumper and let it run unplugged and it stalled in a few minutes. Jumped back again and no stall. Been at 2k RPM for about 5 minutes.

 

[Don S]

Re: 99 4.3 Mercruiser stalling

Great, now, post your engines serial number so we can make sure you get the right switch when you order.

 

[timmyjane]

Re: 99 4.3 Mercruiser stalling

Wow that was an ordeal. I came up with L345703

Found that its Mercruiser part 805024. Not finding it here.

 

[Don S]

Re: 99 4.3 Mercruiser stalling

Yes, that is the correct one. No, iboats does not carry OEM Mercruiser parts, and the aftermarket parts do not match the specs for that particular switch.

 

[timmyjane]

Re: 99 4.3 Mercruiser stalling

Thanks a lot Don for all your help. I really appreciate it and look forward to my next day on the water.