92 Merc 200EFI Over Oiling

[john1961]

I have a 92 Merc 200EFI that is over oiling. The fuel/oil mixture is so stout that I can't get the engine to run over a few seconds. There are no warning horns. Thanks in advance for any help.

 

[WillyBWright]

Re: 92 Merc 200EFI Over Oiling

Welcome to iboats.<br /><br />It can't over-oil. It's gear driven. It can under-fuel. A lot of things can cause under-fueling. One common cause for "over-oiling" is a leak in the fuel system allowing air to invade the fuel line. Drain you VST tank and pump it full with the primer bulb. Also check the lever on the oil pump. There are marks on the pump and lever that should align at idle. If the arm is connected wrong, you'll be pumping at full volume. It'll only lean-out when the lever is near those marks. But even at full volume it shouldn't mix the gas any richer that 50:1. That's the maximum (unless somebody has modified the pump).

 

[rodbolt]

Re: 92 Merc 200EFI Over Oiling

hello<br /> I have seen some overoiling issues with mikuni pumps. not often but it does happen. usually its due to improper adjustment or the seal at the pump shaft is leaking. but if it will run at all I would not suspect its over oiling. I would suspect a high pressure pump or filter.<br /> good luck and keep posting

 

[sledhead041]

Re: 92 Merc 200EFI Over Oiling

After you run the engine remove the cap on the oil tank to check for pressure. The check valve on the engine should release all pressure within 30 sec of shutdown. If it is holding pressure longer then that it has failed and this condition can push oil past the pump.

 

[john1961]

Re: 92 Merc 200EFI Over Oiling

I believe MNMarineMan may have the answer. I checked the fuel pressure today. It is 40psi (a little above the 36 - 39) that I read was good. The fuel was almost black with oil. I really didn't see how the pump could supply so much oil that it wouldn't run, but, oil building up in the vs after shut down answers that. Thank...