1999 Merc EFI BlueWater

I have a pair of 1999 EFI two strokes on a 30 ft Trophy with 105 hours on the engines. Both engines run fine and boat tops out at 51 mph. When I troll with starboard engine for 3 hours or so after 20 min run and have the port engine off(hot soak). When I restart the port engine it idles fine for about 1 min and stalls. If I pump the primer bulb 6 or 7 times it fires right back up and no problem. I changed both bulbs and it still does this intermittently. If I let the boat sit overnight and restart everything is ok. Seems like only with the hot soak it does this. Is it a vapor lock issue or fuel pump losing prime. I think there is a vacuum lift pump on the side of the case and then it feeds to the high pressure pump. I may take fuel psi gauge with me and test on water. Any suggestions. Thanks!

Please feel free to call if you like!

Bugsy
248-88-BUGSY
www.bugsysbaits.com

Re: 1999 Merc EFI BlueWater

On the port side of the engine is the housing where the high pressure fuel pump is located, and on the side of this is a pressure fitting that you can take the fuel pressure at.

I can't remember the specifics, but I think the fuel pressure is supposed to be 35-40 psi at this location.

Hope this helps.

Rick

Re: 1999 Merc EFI BlueWater

I have had similiar issues with my 99 225 efi. Replace water seperator under cowling. Clean Vst unit and also check fuel bulb, Fuel line (if it is grey replace) and check valve at tank. Mine happened to be the grey fuel line. Watch the primer bulb when you are running to see if it sucks down flat.

Good luck

Re: 1999 Merc EFI BlueWater

How do you clean vst unit??? Primer bulbs are new but Jay Smith Racing's called and said to remove primer bulbs that EFI motors do not need them. Engines still have grey fuel line. The fuel line goes through rigging tubes from inside of boat to outside of rear swim platform/motor braket. Not sure if this will be easy or not. What about small block component just before high pressure pump. Is this a low pressure vacuum pump and does it have diagphram??

Thanks!

Bugsy

Re: 1999 Merc EFI BlueWater

Bugsy's Baits said:

How do you clean vst unit??? Primer bulbs are new but Jay Smith Racing's called and said to remove primer bulbs that EFI motors do not need them. Engines still have grey fuel line. The fuel line goes through rigging tubes from inside of boat to outside of rear swim platform/motor braket. Not sure if this will be easy or not. What about small block component just before high pressure pump. Is this a low pressure vacuum pump and does it have diagphram??

Thanks!

Bugsy

Click to expand...

The way it was explained to me by my Mechanic, is yes, that is a diaphragm pump that keeps the VST unit full and inside the VST unit is another 'High Pressure' pump that delivers the fuel to the injectors.

Re: 1999 Merc EFI BlueWater

The small block (fuel Pump)does have a diaphram. There is a rebuild kit available-$30 or so. Very easy to do just make sure it goes back the same. Disconnect lines to vst and use brake or carb cleaner. There are a few small filter screens to clean. Not hard at all. You should be able to run new lines through rigging tube as long as it isn't to tight inside of it. I strongly suggest doing this if you have been using any ethanol. Make sure to keep fuel lines as short as possible. If you have a secondary spin on water seperator-remove it. The one under the cowling is sufficient and efi's have a hard time pulling fuel through both seperators.