View Full Version : Engine stalling/flooding at idle-F.I. adjustment???

08-21-2008, 11:16 PM
I have an '03 X-10 with a MCX, and it just started stalling. I installed a new fuel pump 2 weeks ago, and it has been running fine since then. Drove today for about an hour boarding and tubing with no issues, then on the last tube ride, I idled over to pick up my passenger, and the boat stalled. Started again, ran okay for about 10 minutes, stalled again. Wouldn't start, then waited about 10 minutes, then started again. Ran for about 20 minutes tubing, then stalled again at idle. It appears that when the boat is running slow or idling, it loads up and stalls. After waiting about 45 minutes, went out again to surf, and as we were idling waiting for the ballast to fill, it ran fine. Shut the engine off to get in the water, and engine wouldn't start again. Let sit for 5 minutes, started up was able to run with boat in neutral at about 2,000 rpms, then pulled back to neutral and stalled again. Noticed while in the water, that lots of smoke from exhaust when trying to start, and smelled very rich/flooded. Waited another 5 minutes, got started again, and was able to surf for about 15 minutes with no issues. Then when idling back to pick up surfer, boat stalled again.

My question is, as this is a fuel injected system, is there a way for me to adjust mixture at idle? The boat seems to run fine at speed, but floods/stalls at slow speeds. Had 3/4 tank full during above example. My dealer is about an hour away, so I'd prefer not to have to pull the boat and trailer it there.

08-21-2008, 11:25 PM
No, you can't adjust the mixture. If it doesn't run correctly, it's getting input from a sensor that's causing this. If the smoke was black and smelled like gas, check the coolant temperature sensor and take a fuel sample. If you have water in the gas and it gets past the filter somehow, it'll run like crap. If the coolant temperature sensor thinks the temperature is really low, it'll add fuel.

How is your impeller- have you overheated recently?

08-22-2008, 11:28 AM
Haven't had any issues with the impeller -temperature gauge reads 160 degrees. I haven't ever overheated. Was thinking it might be bad gas, as it happened approx 45 minutes after adding gas. The thing that I'm confused about, is once it gets going, it seems to run fine. No coughing or sputtering. It only seems to be a problem at idle.

08-22-2008, 05:33 PM
If it happened that soon after re-fueling, I would take a sample. You never know what gets into the tanks and they may not be up to date on their filter changes. If it ran fine up to that point, it's not an adjustment, because the ECM program won't change until told to.

How was the gas added- from a container or from a pump? If it was from a container, whose is it and where/how is it stored?

08-25-2008, 01:36 PM
It did happen shortly after re-fueling, but we only added 12 gals via portable tanks. I did add some gas dryer additive,as a "can't hurt" option. I have 4 six gallon containers that I use exclusively for the boat, so I don't think that is the issue. The containers are stored outside, off the ground on a 2x12.

I had a different experience with it the next day. Backed it off the hoist, and idled out for about a minute, then shut it off while I put up the tower and got things organized in the boat. Tried to start it again (about 5 minutes later), and it wouldn't start at all. So the warmed up/temperature issue did not hold true. After checking all the connections again, I decided to pull the distributor cap. All the contacts were very corroded. I cleaned them all with a wire brush on my Dremel, and cleaned up the contacts on the rotor, and tried to start it again. This time, after a couple cranks, it fired and seemed to run good. Took it out for a cruise, and a wakeboard run, with no problems. Then changed riders, ran good for about 3 minutes, then slowly lost power (5 seconds) and stalled. Sat for 5 minutes, tried again, and then ran great for the rest of the day (approx 2 hours).

I'm not sure where to go from here. I talked to the dealer, and they thought maybe the MAP sensor, or possibly an Idle control sensor, but with this latest experience, I'm not convinced that between the dist cap and possibly bad gas, that may be the issue. Thoughts?

08-25-2008, 02:34 PM
Next time this happens, wait for about 5 seconds, turn the key ON, let the pump prime and turn it off again. Turn the key to ON for a few seconds before cranking. If it starts immediately, either the pressure is low or there's something keeping the fuel from getting to the motor.

Take a fuel sample. The reason I keep telling people to do this is from working on boats and I saw all kinds of crap in the gas from boats that had been meticulously stored. I also saw a lot of water in the gas from cans that were stored outside. "On a 2x12" means nothing when the openings are at the top and the vent pops from being heated by the sun.

Do the fuel sample/pressure (you can do both with a decent fuel pressure gauge, since it has a purge valve and clear vinyl line) before anything else. If the fuel sample is cloudy, it's from water mixing with too much alcohol in the gas and that "phase" not fully incorporating into the fuel. Gas "dryer" is just alcohol. Adding that to gas with ethanol is OK if the motor is made for high concentrations of alcohol but it's not great if this isn't the case.

How long does the boat sit when you aren't using it? If it's more than a few days, consider topping it off when you're done. More air in the tank means more water, too. Gas expands and contracts a lot with temperature changes and this makes the tank breathe a lot. Fresh, humid air being
sucked in with a cold front makes it possible for the gas to take on a lot of water, which doesn't leave when the temperature increases.
Where did you buy the gas? Does their gas sit in the tanks for long periods before they're refilled? Have you bought gas there before, or was this the first time? If it was the first time, I would bet that there's something in the tank that shouldn't oughta be there.

Another thing that we were told at training, and I'm not sure all dealers do, is that when the boat is set up for delivery that we should verify the timing advance is set to 10BTDC.

If the RPM gradually dropped at idle, I might be inclined to look at the IAC, which BTW, is not a sensor. If it ran at higher RPM and then gradually died, it won't be that, since the open throttle will provide plenty of air to run on. At idle, the TPS is running things, so I'm not sure the MAP sensor is the culprit. That shouldn't cause the motor to die if it goes bad. The ECT (Engine Coolant Temperature) sensor could send info to the ECM telling it that the temperature is really high and if it leans out too much, it will die. If it happens again, open the motor box and cover the flame arrestor with a towel (be careful of backfires) and if it starts, less air caused the mix to be richer and more suitable for the motor.

If the boat is covered and frequently has condensation when you open it, let it sit open, with the motor box open and air moving around it for a few hours, in case moisture has worked its way into places where it shouldn't be. If you want, remove the plugs from the various sensors, too. If you have a small compressor or a "Can O'Air", blow out the terminals and sensors, where the plug fits in.

How long since the last tune-up? If the plugs, cap, rotor, PCV valve and plug wires are original, it's overdue. Also, make sure the flame arrestor is clean.

08-29-2008, 11:17 PM
Thanks for the suggestions. The boat sits on a covered hoist during the week, but does not have a tight cover on it. Its used on the weekends only (other than a vacation week here and there).

I did top off the tank last weekend before I left. Purchased the fuel from a station I regularly buy from, and haven't had any problems in the past. Took it out today, and started up right away. Went boarding and skiing for two hours with no problems. Then it was my turn to board, and was riding for about 5 minutes, and the engine cut out and then came back (didn't even fall) and worked good for another 5 minutes. I wiped out, then started again, ran for about 2 minutes and it cut out and died. We turned the key on for 10 secs, then off for 10, on for 5, and then started it. It ran fine for another 25 minutes until we parked it.

I don't have a fuel pressure tester, so I'm not able to check that here. Is there a basic one you can recommend for me to purchase?

I purchased the boat this spring, so I don't know the history of maintenance. I'm guess that plugs, rotor, cap and wires are all original. I am planning to replace them all this fall, as well as cleaning the air intake/spark arrestor.

This kind of stuff drives me nuts, as it doesn't seem to be consistent...

08-30-2008, 08:56 AM
How low was the fuel level? Find out if the previous owner ran out of gas- these pumps don't live long when that happens.

I got my fuel pressure gauge at Sears- it has a purge valve and a clear vinyl tube, which it for collecting any gas that comes out and makes it easy to take a fuel sample, which I highly rem=commend doing.

Your cap, rotor, plugs are about done if it has a normal amount of hours on it (~50 hours/yr). If it has more than this, definitely inspect them, at the very least. I have a Chevy pickup and use the Borg Warner cap/rotor from Checker Auto Parts and if you have Schuck's or Kragen, it's the same company. The B-W I use have a lifetime warranty- ask about these when you go. Why keep paying for them when all you need to do is keep the receipt?

Some here have mentioned that the black siphon tube on the pump has been found to be kinked- maybe you need to look at yours to see if this is the case.

09-03-2008, 10:17 PM
I've checked all the hoses for kinks, and that doesn't appear to be the problem. I replaced the fuel pump about 4 weeks ago, as I thought that was the problem. The engine ran fine for two weeks after the replacement, and I thought I was set. Then things happened as I mentioned in the first post. I'm starting to think that it is something to do with the electrical connection to the fuel pump. Way back on the very first run of the season, I backed it off the trailer, and it was idling fine. I put it in gear and it stalled. It wouldn't start. I disconnected the two plugs to the fuel pump, and then plugged them back in, and it ran fine. Three days ago, I tried to start it cold, and it just cranked and cranked, and it wouldn't fire. I took the distributor cap off, cleaned the contacts, and tried again, still nothing. I disconnected the two plugs to the fuel pump, and reconnected, and then it started. The thing that doesn't make sense to me is why would it die when we're just running along? I've been topping up the tank before each trip, and we can run for 2 - 3 hours with no issues, then it just stops. The last time it stopped and wouldn't start, I sat for about 5 minutes, and thought about the 2 plugs. I disconnected/reconnected and then it started. The plugs I'm talking about are a 2 wire and a 3 or 4 wire, that connect right to the top of the fuel pump. Thoughts?

09-03-2008, 10:34 PM
Make sure the terminals aren't spread too far to make reliable contact. You can use a small screwdriver to bend them closed slightly but don't bend them too much- they can be brittle. Also, make sure they aren't corroded. If you want to do a wiggle test when it's in neutral, go ahead. Sometimes, the wire will break inside of the insulation. Tugging on the wire and holding the plug in place is a good way to do this.

Vibration can easily cause this kind of problem to be intermittent.

This kind of problem is why a shop can work on something for 20 hours, not find a problem and then the customer takes it out and it shows up immediately.

10-01-2008, 01:04 PM
Thanks for all your responses Jim. Took the boat in for winterization, and explained the problem to the mechanic (along with your thoughts). Turns out it was the connector to the fuel pump. Apparently one of the teminals was bad, and would make intermittent contact. They ordered and installed a new connector. I'm pretty confident that my previous fuel pump was okay and didn't need to be replaced. I guess I've got a spare one now.

Hopefully this solves my problem, but I won't know for sure until next season. Thanks again for all your ideas and suggestions.

06-22-2009, 12:25 PM
Got the boat in the water for the first time this season, and ran into the same problem I had last year. Runs for a while, then cuts out. I checked the connector to the fuel pump, and it was extremely hot. Disconnected it, and found that inside the connector, it had melted some. Scraped some plastic away from connector, and squeezed it shut, and reconnected to fuel pump. Was able to run for about 20 minutes, but still was extremely hot. The connector has 3 wires, black, gray, and green. The wires didn't feel hot 4" away from connector. I'm guessing black is ground, green is power, gray ???

As a recap of this thread, I had replaced the fuel pump unit, and then had the connector replaced during the winterization. My thought is the old connector was "loose" because it, too, had melted from heat. Any idea why there would be so much load that it would make the insulation around the connector melt? The dealer's suggestion is to replace the pump and the connector at the same time. He thinks the old connector ruined the new pump. And the new connector was ruined because of the pump. I'm not excited about spending another $450+ on a pump when the other one has less the 20 hours, and my original one probably wasn't bad in the first place. Ideas on what to do next?