Bad Fuel/Water Seperator/Filter?

[isaacs]

Today, while underway, my 2002 5L engine started to stumble and hesitate. It got progressively worse over the course of about five minutes but I made it back to my launch without incident.

When I got home I was thinking of possible fuel problems and realized that I had not changed my fuel/water separator in several years. When I got home I changed the filter and when I dumped the old one out it looked more like water than gasoline; I wish I had saved it in a clear bottle so I could be sure.

I started the engine and it continued to stumble for about thirty seconds then it smoothed out and ran perfectly for about twenty minutes after which time I shut it off and patted myself on the back for fixing the problem. I'm thinking It had to run the bad gas out of the fuel line between the filter and carburetor before it got the good stuff.

Not knowing much about these filters I have a couple of questions. Is this typical? Do they simply fill with water 'till it starts getting mixed with the fuel and pumped into the carburetor? Would this make the engine behave as I have described? I should mention that this boat sees very little ethanol. I use E10 only early in the season when I know I will burn through it before it's time for winter storage. Would a lack of ethanol in the fuel cause any water to wind up in the filter rather than getting mixed with the gas?

One final question. Is there another filter at the carburetor like the old GM cars used to have?

Thanks in advance and sorry to be so long winded! Bob

 

[Rick Stephens]

Probably a filter in the carb inlet.

If you filled the fuel water separator with crap you need to rebuild the carburetor and get the junk out of it. The other filters won't stop water, and water mixed with your fuel will leave gunk everywhere in the carb and back to the tank. Check your tank carefully that it doesn't have a bunch of water in the bottom waiting to screw you over again. Pull the fuel gauge sender and look. If the fuel you use has ethanol in it, the water will quickly bind with the ethanol and lower the fuel octane level. So lots of stuff to consider.

 

[Bt Doctur]

More of an operator error not a filter error. You change it every year

 

[dingbat]

The good quality filters use specially treated elements as part of the water separating scheme.

As such, separating filters need changed once saturated or annually, whichever comes first.

 

[isaacs]

Ok, I took the boat out on the river today and it is still sick. It is not a fuel problem but it is electrical. Whenever the engine stumbles, the voltage gauge goes to zero and immediately recovers to 13 volts. It's as if someone is quickly switching the ignition switch to off for a split second, then returning it to run. When I first started the boat it was so bad that it had trouble idling with the gauge wildly swinging back and forth. As I drove it around things improved to the point that by the end of the day it was running perfectly but I can't trust it. It doesn't seem to be the ignition switch because the oil pressure and temperature gauges don't move--just the voltage.

I spoke with a mechanic and he seems to think it's a bad connection. Battery connections are good, I wiggled all the wires to the ignition switch and there was no change. I wiggled all wires I could reach in the engine compartment, no change.

I'm wondering if the alternator is bad. Could that cause blinks in the power going to the ignition? I'm having no problem with the battery staying charged; I stopped and started the boat several times during the day. Does the power for the ignition somehow run through the alternator? I would think that as long as the battery is good, the ignition would work.

Another odd thing. Whenever the boat is misbehaving the problem can be made worse by turning on the blower (which works just fine) or even keying the mic on the marine radio. It seems the smallest power draw is enough to send the engine and voltage gauge into fits.

Any ideas? Thanks, Bob

 

[dingbat]

It doesn't seem to be the ignition switch because the oil pressure and temperature gauges don't move--just the voltage.

The oil and temp gauges are not electrically driven. They would work unpowered.

My money is on the ignition switch

 

[Camaro4life18]

I'm new to boats, but this sounds like a bad engine ground. If the alternator was bad you would run on battery power until the engine died. If the ground to the battery is corroded or loose it would behave like this. Follow the ground from the battery to the engine and make sure it's clean.

 

[isaacs]

The boat is running perfectly now and unless it starts to fail again, I can't learn much from a 12V test light which I will be keeping in the boat in case it starts stumbling again.

The oil and temp gauges are electrically driven with a sensor wired to each. When the key is turned off they immediately jump to the far left. The only thing that is mechanical is the speedometer. Because of this, I feel that it is not the ignition switch. The only gauge that jumps to the left is the voltage and it happened every time the engine faltered.

I've checked the wiring from the ignition switch (purple) which supplies all the gauges and runs back to the coil. I even removed the shrink wrap from the connection point for all these purple wires and it is tight and looks like new.

I was able to trace the purple wire over to the lanyard safety switch. It is operating properly and when I switch it off the engine stalls but the voltage gauge stays steady..

The shift interrupt switch in the engine compartment seems to be operating correctly. If I manually activate it the engine stalls but the voltage gauge stays steady.

Grounds at the engine and battery are clean; connections to the coil look good--this boat has never seen salt water and has very little corrosion anywhere.

If the coil or ignition module were bad how could they possibly affect the volt meter?

Because I can't trust this thing I'm making up a wire with some clips on it to hotwire the coil and hopefully get me back to my launch/dock if things get worse. I would love to get a test light on the 12V side of the coil during an "event". It would tell me a lot.

Keep the suggestions coming, Bob

 

[isaacs]

UPDATE: I know this thread is getting old, but I thought I'd share the fact that my boat is FIXED!

It turns out that the voltage gauge fluctuations were a result of the engine faltering, not a cause. I think the gauge is more sensitive than the others and it would swing quickly down to ten volts which is its lowest point whenever the engine stumbled and slowed down. It's just a cheap meter and the needle probably has a lot of inertia showing more of a voltage swing than really exists.

I was almost left stranded about thirty miles away from my launch--it took me an hour to get the boat started. The next day I worked on the boat in a state park parking lot where I was camping. I tried a new coil with no change. Fortunately, no one nearby had a replacement alternator or I probably would have thrown one of those in. ($$$!)

I took the distributor cap off and it had the usual green boogers in it which I cleaned off like I always do. (Why does it do that?) I had determined that I had little to no spark by putting a towel over my head to block the sun and shorting the coil wire out to a ground. The rotor looked like crap so I headed to a nearby marina to get a new one and hopefully some information knowing that the rotor wouldn't affect the spark at the coil.

The guy at the marina was really helpful. He said it was probably the sensor at the bottom of the distributor that runs to the Thunderbolt ignition; he said they go bad all the time but they were on backorder and he didn't have any in stock. Just my luck! Fortunately another marina had one and I was back out on the lake with a boat that runs perfectly. No more problems!

Just a note to anyone else that may be changing one of these sensors. One of the screws that holds it on has a nut on the bottom to hold a ground wire. This screw can't be backed out without first removing this nut which isn't a fun thing to do in a parking lot with nothing but a screwdriver and a pair of cheap vice grips. An open end wrench would have made a big difference.