Merc 30jet dies at wot

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xFORBESx

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Had the boat out for the weekend, ran good Saturday, then on Sunday the motor died at full throttle, and would start up again. After a few minutes it fired up, and 15 seconds after getting back to full throttle it died again... I'm going to replace the fuel filter. There are no leaks in my lines, and the primer bulb gets hard after a couple pumps. Is it possible the pump is bad, or whatever the diaphragm thing is in the photo?
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The fuel filter would be where I would start. If the filter is dirty the fuel may not be getting through it fast enough to keep it running. After sitting a couple minutes the fuel can seep through enough to keep it running again for a short period, shorter if at wide open throttle.
 
That's my first swap for sure, sucks when these things happen cause I have to drive 18 miles to test it out.


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Does it matter which fuel filter I get? Or should I order a specific outboard inline filter?

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A standard inline Sierra filter from an auto parts store works fine for that outboard in that application. Also, the rebuild on the fuel pump is really simple. You can knock it out in about 30 minutes. I have the exact same Jet 30 and rebuilt the fuel pump last year.

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Thanks for the info striper, where did you buy the rebuild kit for the pump?


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I bought my kit from Bass Pro's Tracker Dept. because I wanted/needed it that day, so I paid a little more. You can order it online if you don't mind waiting for about $10 to $15 less I believe. Just make sure to use the actual Mercury gasket rebuild kit. I don't mind using an aftermarket fuel filter because I replace mine every year or two, but I learned a long time ago never to skimp on gasket kits and whatnot.

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Check your fuel line connections from the tank to the motor to make sure they are tight and the O-rings are sealing properly. I had a connector that would leak air into the fuel once in a while and it would bog down. It sounds like the filter is clogging up or the pump diaphragm is going bad. I had a filter clog up and it would stall out. I didn't know what it was and I squeezed the ball too hard and blew out the filter. Then I had to take the carbs apart to clean them out to get everything running right again.
 
So I changed the fuel filter, put fresh gas in the tank. And it started up and ran good the last time out. Took it out today and it ran great for 30min then died... got it off the water after 2 hours of running the trolling motor. After getting home I rebuilt the fuel pump replaced a couple lines. And still nothing! Plugs are clean... any ideas would be very helpful!

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https://youtu.be/Bn-M0SYKhQ0

You could try setting the floats on the carbs. I had to do it once years ago. Forgot I had even done it.
 
Just spent an hour looking things over. And remembered I had issues getting it to start a few years ago. And at that time it was my push to choke ignition switch... messed with that for a few minutes and boom she fired up. Guess I have to buy another switch.

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xFORBESx said:
After getting home I rebuilt the fuel pump replaced a couple lines. And still nothing! Plugs are clean... any ideas would be very helpful!

If you can narrow it down to spark or fuel, then it gets easier to fix.

Check for spark when it dies. Another trick is to squirt a small amount of gas directly into intake.
 
xFORBESx said:
Just spent an hour looking things over. And remembered I had issues getting it to start a few years ago. And at that time it was my push to choke ignition switch... messed with that for a few minutes and boom she fired up. Guess I have to buy another switch.

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Did you get it worked out? Or waiting on parts?

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So the ignition switch that I ordered is different from what I had, in that it is a 7 position, and the old was a 6 as shown in the photos. I wired the new one up like my old one and got the motor to start after some were swapping, but the key would shut it back down. Are any of you guys familiar with these? I have my red battery wire, yel/blk, 2 blk ran into one connector, 2 blk/yellow in in one connector, red/yell, and 2 purple in one connector. I can't find a good diagram... (first pic is new key)
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I think I got it figured out, I had to leave terminal A empty, motor is running again. Hopefully for a while now, wife said no more money can go into the boat this year...lol

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Wiring can be so much fun! #-o My Mercury 60/45 came with a cut up wiring harness and the used controls I bought also had cut up and burned/melted wires. I managed to get it running but when I moved the console forward I needed a longer harness and bought some new stuff off Ebay. I actually decided to bypass the neutral safety switch since it's a jet and sometimes when fishing I need to fire it up and move quickly to avoid rocks so I can put it in forward and start it right away.

On my jet sprint boat, it came without an engine or jet drive and there was a wiring harness from the dash to the back. I had to find out what brand harness it was to buy the other half of the harness and then wire up everything to the 350 Chevy engine that came out of a Corvette. It wouldn't crank the engine over but you could hear a faint click when you tried. I took the starter to Autozone and they ran tests on it and it was fine. I tried a new solenoid and that didn't matter either. I finally ran a new test wire from the ignition switch to the starter and it cranked over. It turns out the original wire in the harness was too weak to carry the amperage to the starter. The engine has an HEI distributor so I had to run a separate wire for that as well. The boat didn't have a kill switch so I had to add that and make sure it turned off the electric fuel pump but still leave it able to run the bilge pump.
 

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