1994 4.3lx not starting and blowing ignition fuse

[jakehorton15]

Good afternoon everyone, last weekend we took the boat out and had some issues. Boat has a 4.3lx thunderbolt 4. Took the boat out the first night after changing cap and spark plugs and new batteries and she ran great for 30 minutes up and down the lake with no problems at all. When idling back into the marina it started to lose power and died out when going from idling to accelerating quickly but started right back up so we took it back in and docked for the night.

The next day we go to hit the water and boat starts right up first turn of the key for about 2 seconds then dies, turn the key again and cranks for about 2 seconds then nothing, turns out the ignition fuse under the dash had blown. We swapped it out for a new 20 amp fuse and did it again, blew 3 fuses in a row. so we jump the fuse with a wire and it cranks and cranks but no start. We were getting no fuel pumping into the carb when we would hand pump the throttle and the fuel pump wasn't humming when we first turned the key to the on position. With starter fluid in the carb it would hiccup and try to start and then die out. We got a tow back to the ramp and headed home.

Weve had weekends where wed go to launch and it would crank and crank but wouldn't start and no gas would be pumping into the carb. Weve checked the anti siphon valve and it looked fine and the hoses seemed fine and changed the fuel filter. Is this possibly a bad fuel pump issue? Could a bad fuel pump cause too much draw and blow the ignition fuse? Im kind of confused trying to research and track down this problem so hopefully someone can help. Thanks alot, Jake.

 

[alldodge]

Fuse blows you have something drawing to much current. Don't bypass the fuse, need to fin out what is blowing it. Everything that has a purple wire attached to it can be the problem. Ignition module, coil, alternator, fuel pump switch (grounding), electric choke. Since your not getting spark with bypassing the fuse, look at the distributer and module. Did a wire get pinched when the cap was replaced?

 

[Rick Stephens]

Your fuel pump and spark will not run when there is a short in the purple wire circuit. Purple is the hot wire that leads to everything from ignition, to oil and temp senders, to the fuel pump and charging system.

The starter is direct connected to the battery with an independent wire running to the solenoid from the ignition switch. A short in the purple system will probably not effect the starter.

First thing to look for is something cooked, melted connector or insulator material. Next a worn through and shorting wire. After that comes down to disconnecting things or individually testing each component.

Rick

 

[jakehorton15]

Thanks for the quick replies guys. Ive been reading about the purple wire being shorted in other posts so ill start looking at that first. And im assuming that im getting spark since when i use starter fluid in the carb it tries to start of and fire but ill use a test light and find out forsure. Thanks, keep the suggestions coming while i check those possibilities

 

[jakehorton15]

also just to double check when you guys mention looking for shorts in the purple wire, is that just the solid purple wire or any purple and stripped wire as well? Thanks

 

[alldodge]

I would go and remove all the purple wire connections from the items listed above, make sure they don't come in contact with a ground. Put a new fuse in line and turn key on, then start reconnecting the wires one at a time until the fuse blows again

 

[Rick Stephens]

I would go and remove all the purple wire connections from the items listed above, make sure they don't come in contact with a ground. Put a new fuse in line and turn key on, then start reconnecting the wires one at a time until the fuse blows again

Oooh, that's pretty smart.

 

[jakehorton15]

Dang you guys sure are good! I got to work on the boat today and got to digging around and sure enough the purple and yellow stripped wire coming from the oil pressure switch had been bumped against the block/manifold and had burned through the jacket on the wire to ground it out. I taped that up really well along with the other wires around it and cranked it for just a second and she fired right up no problems!! You all have been a huge help once again. Thanks!

 

[Rick Stephens]

That's awesome. Congrats on a simple fix. Happy boating.

Rick