2007 mercury pro xs suddenly shuts down

[bassbusterguy]

I have a 2007 pro xs that has run flawless until now. The engine will start properly first thing in the morning then suddenly shut off with no warning beeps at all before i can back away from the trailer. It will turn over and attempt to start for a split second then suddenly shut off. I can flip the kill switch and turn it over for a second a hear the difference that there is no spark. I flip the switch back and it starts for a spilt second then quits again. i can squeeze the primer bulb and it feels firm. One solution to get it to keep running after it starts to do this has been to tilt the motor up for a couple of minutes then tilt it back down and it starts and runs fine. Later after a short run and I have fished for a while with the motor down it might do the same thing again. I tilt it up and back down and it starts and runs fine. It has on one occasion shut off without warning while on plane. The weather has cooled off a bit and seems to have started to act up now that it is cooler. There have never been any beeps other than the single one at start up. I can here fuel pumps run when i first turn the key on and one single beep. After it starts a stays running it performs flawlessly until i turn it off and it decides to do it again. It does not do it everytime. It seems to happen at the first start up and after the motor sits and bit in the trimmed down position during the day. The tank is 3/4 full of fuel that contains the proper amout of stabill in it. The batteries are newer and check out just fine and all the connections are tight to the batteries. The key switch seems to work normal. the lanard or kill wire is fine. The oil tank is full and caps on the tank are tight. The engine oil tank is completely full. Is this a filter problem?

[bassbusterguy]

its a mercury 250 pro xs......

[EuropeanAM]

Off the top of my head.... probably one of THREE things:

-Ignition switch harness may have an "adapter" at the engine end (1' long adapter from 8-pin cannon plug to 14 pin deutch connector). If the cannon plug pins are LOOSE (should be clamped) or dirty, this can occur. Keyswitch or lanyard switch are also possible.

-Debris in VST or sticking float valve in VST. As for debris.... sometimes a piece or red plastic "shard" from a removed fuel filter will find it's way into the passage between the filter housing and the needle, causing this sort of problem. If this is the case, the VST would need to be COMPLETELY disassembled, and EVERY PASSAGE cleaned and checked (as well as blown out with compressed air). The particular passage I've mentioned would need to be cleared with compressed air BACKWARDS (blowing into the seat for the float needle pushing any debris back into the filter chamber).

-Main Power Relay.

[bassbusterguy]

Thanks.....I checked the wires and they all seemed to be tight. I'll get it into the dealer and have them take care of it. It's under warranty. I love this 250 pro xs engine. Had the 225 before on a slightly different hull and there is no comparison. The fuel mileage is awesome with plenty of power for an old guy like me. Again thanks for the quick reply...

[JAZII]

I'll go with a bad ING. key switch.
Post back when the problem is corrected.
JAZII

[bassbusterguy]

The outcome was debris in VST . The fuel line was breaking down.

[EuropeanAM]

Glad to hear you found the problem!

As for the fuel lines breaking down, I HIGHLY recommend that you look over the following post (and ensure you're using the correct fuel line):

http://www.bbcboards.net/zerot...first

[bassbusterguy]

oops! .... Took it out Friday afternoon air temps low 80's and it started and ran fine. Went again Saturday in the early am with air temps at 50 degrees and it started and cut off after a split second. Tilted motor and it started and ran fine for 50 yards in gear at idle speed then cut off as if you pulled the lanyard. this time i just jigged the key in and out and it started. Ran another 25 yards in gear at idle and cut off again. I had my hand on the cover where the key is mounted and there is some steady vibration there when the motor is running. Maybe it is the the key switch causing this problem? Used the trolling motor for half a day. At 11am I tried it again with the air temps back to almost 80 degrees and it started just fine and ran without issues back to the dock and restarted without issues for loading onto trailer. I,ll take it back to dealer for another look. I,m sure they found issues with the debri in vst and they thought that was it. Turns out there might have been multiple problems ......

[EuropeanAM]

The next logical step would be to install a "test" (or transom) keyswitch harness to the engine, and run it to see if the problem is gone.

This helps to rule out (or in) problems with the boat's ignition switch harness, keyswitch, and lanyard switch.

[gasaxe]

a freind of mine had a similiar issue with a 200 efi 3.0L 04 model. motor had set for an extended period of time before being put on the boat when he bought it. It would die unexpectedly most of the time when the motor/air temps were cooler. It slowly became a more regular experience again only when air temps or motor were cooler and began to cut out and die when up trim was used. Local repair shop disconected the main harness plug on the motor and expanded the male pins and this fixed the problem. I wasnt there when he had it fixed but he watched it done and this is what he described to me. The main thing that tipped the mechanic off was that the last time we had the boat out it died and all power to the ignition and smartcraft gauges went dead. As soon as i just touched the cowl power came back. I assume the pins were not making good contact inside the plug.
hope this helps!
brian

[bassbusterguy]

It was two issues that caused my sudden shut downs. First they found debri in the vst from bad fuel lines. Second they replaced the key switch. I have tested it numerous times in very cold weather and it starts and runs like a charm. I did notice the old key switch had no drain hole to let condensation out. The new switch had a drain hole and large warning sticker attached with caution to install with drain hole down. THIS MUST HAVE BEEN A PROBLEM and this new style switch helps eliminate any condensation that may build up. Thanks for all the replys they were very helpful..

[EuropeanAM]

Glad to hear you got it fixed!