Fuel-Injected Fogging

[jguarniere]

I would like to confirm the engine fogging procedure for late 90's fuel-injected MerCruiser engines (specifically a 1997 7.4LX MPI):<br /><br />1. Remove the flame arrestor cover, which will expose the throttle body with the dual throttle plates.<br />2. Run the engine (with flushing water) at idle, while spraying fogging oil through the plates. Increase the engine speed slightly if necessary to open the plates further.<br />3. Stop the procedure if the engine stalls, or until smoke is continuously exiting from the exhaust.<br />4. Drain the seawater cooling system and fill with antifreeze.

 

[rodbolt]

Re: Fuel-Injected Fogging

Hello<br /> no that is no longer the merc procedure. there is a tech bulliten about mixing 1/2gallon tcw-3 with stabil in 5 gallons of gas and running it at 1000 rpm for 10 min. I am not positive of the exacts but I have it on the board at work. something about keeping the injectors and fuel pumps from sticking.<br /> good luck and keep posting

 

[garycinn]

Re: Fuel-Injected Fogging

Here is the recommended Mercruiser EFI fogging procedure:<br /><br /> Fogging Service Bulletin <br /><br />Don't make a full 6 gallons! That is for a shop doing a boatload of boats. If you do the math, it is a 10:1 ratio of gas to oil mix. Just make up a half gallon and put in 6 or 7 oz of 2-cycle oil and your favorite stabilizer.<br /><br />This is how I did it. Removed the rubber low pressure fuel line right before the fuel separator, hooked up a outboard tank with the mixture. Pumped the bulb to prime the outboard line. Started the engine on muffs and started timing once the mixture started to go down. Once the time was up, remove outboard line, remove old fuel filter and install new with either the mixture or stabilized fresh gas. Install original fuel line.<br /><br />I expected the boat to smoke more when the 2-cycle oil hit. It wasn't that bad, but you can tell a trace of smoke out the exhaust.<br /><br />I may hook up a 3 way fuel valve with outboard connectors to make this whole process really quick in the future.

 

[mojokim]

Re: Fuel-Injected Fogging

Gary, totally off topic but where in Cinci. I live on the east side. You can e-mail me off line at mojokim@fuse.net Don't want to tie up the thread. John

 

[rodbolt]

Re: Fuel-Injected Fogging

hello<br /> one more add in. be very careful when connecting/disconnecting fuel lines at the filter head. some systems pressurize the fuel filter with the return fuel from the fuel rail. some MPI engines merc reccomends waiting 12 hours berore removing filters. good luck and keep posting

 

[garycinn]

Re: Fuel-Injected Fogging

Rodbolt brings up a good point about fuel pressure. Just to be sure, wait the 12 hours or check with your specific Merc manual or mechanic if your boat has that issue.

 

[jguarniere]

Re: Fuel-Injected Fogging

Gary: Thanks so much for the very helpful information! Is there a specific hose size that I should purchase with the outboard fuel tank, or does the standard outboard line/bulb fit the MerCruiser fuel filter's inlet? And to confirm, the 1/2-gallon mixture is enough to fog a V8?

 

[garycinn]

Re: Fuel-Injected Fogging

The Mercruiser fuel barb just before the fuel separator fits a hose with 3/8" inside diameter.<br /><br />Yes, I believe most outboard hoses are 3/8" ID.<br /><br />I ran my 4.3L EFI V6 for a good 10 minutes at 1000 rpm and barely dented the 1/2 gallon, so you should be fine.