Fuel Problem??? - MerCruiser

[WakenSki]

I thought I'd tell you what happened and based on this story maybe you have some ideas on where I should start. I have a 2004 Switch 20i w/MerCruiser 350 MAG MPI.

Two weeks ago we were out for the first time this year, engine started and ran fine. Once while skiing the engine struggled to maintain RPM (at about 2200) but then came back up. I thought maybe bad gas from the off season (although we filled the tank on the way to the lake that day) so I ran it hard back to the landing and it ran fine. I put a can of SeaFoam in the tank as a result. Yesterday, boat started fine, I idled out to the middle of the lake (I like to warm up the engine before towing), when I gunned it to start towing, the engine struggled and then stopped. I could not get it started again. Ended up getting towed back to shore. Just for the hell of it I tried starting it at shore after the tow, it popped off but then died right away. Sounds like fuel supply to me but does anyone have any thoughts before I take it in - maybe something I can fix/replace/check?? BTW, I did replace the fuel filter/seperator last fall.

Thanks,
WakenSki

[dogbert]

A couple of thoughts. One possibility is that it is indeed a fuel supply issue. Another is that you're having ignition problems. I'd start with pulling one of the plugs. If you have fuel in the cylinders, you have an ignition problem. If that's the case, I'd examine the distributor cap. If you have any carbon, replace it and the rotor.

If that's not it, then you may have a fuel pressure regulator issue. On your boat it'll be located on the port side on top of the fuel cooler. I'd check the pressure first...I think there's a valve on the rail to do this. Otherwise, this may best be a job for a skilled mechanic.

[R&T Babich]

... BTW, I did replace the fuel filter/seperator last fall...

How much fuel was in the tank?
The separator may have water in it from condensation in the tank over the winter.
Try pouring the contents of the separator into a glass jar and see if there's any water.

If you get a fuel pressure test gauge or mount a little gauge on the end of the fuel rail the fuel pressure should read around 26 psi with ignition-ON or running.

[WakenSki]

There was about 5 gallons over the winter, then added about 20 gallons this spring. I'll try dumping out the seperator and see what I get. I did find the pressure port for the gauge but I don't have a gauge. I'll screw with it a little this afternoon otherwise to the shop we go.

Thanks for the advice!

[WakenSki]

I took the fuel filter off and it was about half full. When I changed it last fall I had gas all over! So I disconnected the fuel pump, hooked it up to 12v, it sounded good (not sure what a bad one would sound like) but no fuel. So I took the supply line off and tried blowing in it (back up into the tank to make sure it was open - listened for the bubbling) that was blocked solid. So I opened the truck panels. The vertical truck panel almost rests against the fuel tank. The supply line elbows off the tank straight back toward the trunk panel then down. With the wedging effect of wide kneeboards, the trunk panel kinked the fuel hose. I rotated the fitting about 45 degrees clockwise to ease the bend. Tried the fuel pump again and "I got gas"! Next is to lake test it but I'm 99% sure this will fix it!

[dogbert]

Cool. Although I would never have called that one in a million years. Glad you figured it out!

[WakenSki]

Lake tested it this afternoon - ran just fine. I got off cheap on this one! Thanks for the advice guys! I wonder how much that would have cost me in the shop????