changed fuel filter and separator (EFI) - runs likes crap
 

2006 EFI Merc Black Scorpion in Sanger V230

Started the season off with fresh fuel filter, separator and impeller. Been out quite a few times since then, boat was hesitant to start first time out after service. Thought it was air working its way out of fuel system.

Now at least 15 engine hours later, I still have an issue after about 5 minutes of being on plane running 15 - 20 mph. Engine will stumble and drop anywhere from a few hundred to a thousand RPM. Often perfect pass revs it a bit and you can barely tell a difference in the wake. Other times, we have to drop the rider and restart cause the boat won't maintain speed. Never dies, solid hole shot, cranks every time. So that rules out bad gas I thought I got from a shady station.

Acts like a fuel pump issue, losing pressure after a few minutes of running it. Only 370 hours, so I'm not convinced its the pump. Can hear it power up and charge the system with key on. Keep going back to my garage mechanic skills and not sure I primed the system properly.

I didn't fill the separator with gas when I put it back on, about the only thing I can think of.

Should I take the engine cover off and try check for air in fuel rail? Whats best way to get all the air out? Or do I have something else going on?

Have taken the cap and rotor off and looked at the point to see if there corroded or changed the plug wires. I had to do this last year on my 06 supra. They had never been change and the boat started running like crap. I thought it was bad fuel too.

Start with the basics . Make sure your battery voltage isnt dropping or fluctuating as well computer controlled engines need solid voltage one weak battery and a big stereo can wreak havoc . Bad gas could still be the issue or possibly a ton of water in the fuel . I'm not sure where you live but condensation will create a lot of water . And of course check the cap and rotor and everything else.

Could buy an in line spark tester and make sure all plugs are good. Tool is only about 20 dollars.

Does yours have the screw on fuel filter or the one in the black box housing that you loosen 3 bolts to remove?

Check all your electrical connections. At battery and block. Check cap and rotor/plugs/wires. If all checks out check fuel pressure at fuel rail.

Thanks for the ideas. A little more background, I use the boat regularly. Batteries are 3 years old and in good shape. Haven't touched main grounds or any of that ever. I did recently add an amp and sub. but they're on a different battery separated from engine electrical system with a perko switch.

Gonna start with cap/rotors then go from there.

I have a threaded oil filter style fuel/water separator. and a fuel filter in a black housing. I think the black filter had a plastic band holding it to the stringer

^^^^^THIS.

I was having hesitation and it was intermittent. I found all sorts of corrosion on my distributor cap. I thought that was THE issue, but while things were better after changing the plugs/cap/rotor, I still had issues. changed the plug and COIL wires and now the boat runs like a boss. I found some visible corrosion in the end of the coil wire, so I think that was certainly a factor. The plug wires were expensive (over $100) because they were specific to the Indmar setup, but got a bit of a discount at Bakes and it's so worth it to have a boat that runs well.
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Mine looked exactly like yours.^^^^

at 370 hours, they've probably never been done. although it looks like someone recently numbered all the wires and marked them on the dizzy cap. I'll pop the cap off tonight and take a look.

thanks guys, I never would've thought to check cap and electrical system for what seems like a fuel delivery issue.

it's a spark issue. the boat is missing and retarding timing. Your boat is going FULL RETARD!!! :banghead:

Make sure you also take a look at the terminations on your coil wire. that's where mine also had corrosion.

NOOOOO!!!! lol!

ya know I saw some corrosion on what I think are coil leads. gonna pop black scorpion cover off take a look at things. fuel rail pressure, cap, etc

I honestly don't think it's your cap and rotor, but you can check it and replace if you want. I would hook up a fuel pressure gauge and go out and run it in the same scenario that it does it to see if it's a fuel problem. The reason I say that is because typically a spark issue is really present under hard acceleration (hole shot). It doesn't run fine, then just cut out 5 mins later, then go back to running fine. It seems more along the lines of a fuel/air problem, but if your pressure never drops, then it's more towards a bad IAC or your coil breaking down once hot. Maybe even vapor lock. How hot has it been while you've been out running it?

under the conditions above, 158*
If I run 35-WOT for 10 minutes + I'll see 180* but it cools down quickly

Picked up a fuel gauge yesterday.

T not true a bad connection (loose) will be very sporadic. You installed a new amp? Boom! Check your perko bolts and battery cables for looseness.

If everything is tight and pressure is good. I'd check the iac valve next.

Cap and rotor looks like chit. Dizzy went full retard for sure
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Gasket was torn and it only had 3 of 4 screws holding it down. Pretty sure I found my problem.
Guess moisture condensed in there when it cooled down.

Hard to tell in the pic, but every contact had 1, sometimes 2 green corrosion scales on it. Ordering a new one

I should replace rotor but couldn't get it come off. Mine might be rusted to the cam gear shaft with all the moisture I've got

Take a pair of flat head screwdrivers and pop the rotor off. It's not the worst I've seen, but it does need replacing. Give it a shot and see if it fixes your problem.

I've seen a lot worse, but you should at least sandpaper the cap and rotor annually, especially if you leave the boat in moist conditions. Gasket being torn doesn't matter much and you might be able to find the 4th screw in the bilge. If you sandpaper them up a little, you can be back in business in 5 minutes. I'd replace it when you get the new one, but not every year. Just sandpaper it a little.

99.9% of Black Scorpion owners of the same design will have the same thing happen, so don't feel special.

Nice. Like the sandpaper fix. Wanted to go out tomorrow so that helps. Cheers

Good deal. I've super glued that gasket before when it tore. Maybe you can use a twist tie for the other screw...although 3 might work for a bit. Good luck.

Sounds like a coil to me. I say that cause these are the exact same symptoms my wife's Nissan was having, would start run fine the act up. Was just one bad coil that would cause the cylinder to misfire

a hot coil on the fritz is a close second IMO. Pics don't do justice to the moisture and corrosion in the cap. Good idea.I lose timing when it misses so ima check coil voltage too

Called it first LOL

still haven't found the issue.

sandpapered the cap and rotor. cleaned all the moisture out. reinstalled. boat fires up in the driveway. Load boat and truck with cooler and gear for 4, get to ramp - won't start. Fuel pump isn't kicking on. Last time out, same symptoms but eventually started. killed and restarted it 5 times. seemed fine, took it out for a nice day on the water. no issues.

batteries are charged. back to square one.

Key acc on, no pump sound. Don't have the normal beep with accessory on either....

fuses? breaker?

started in driveway. breaker isn't thrown.

think i have a line on a code reader. I'll post what I find.

fuel pressure regulator is one thought, but the pump should come on regardless

Do you have a safety kill switch lanyard thingy mabob? And did you check all you power feeds from battery/Perko and on motor side the ground. Off and on BS is usually loose power or ground.

The fuel pump should not run on the ACC side of the key switch. Only the radio or whatever you have hooked up to it should be on. The fuel pump should come on for about 3 seconds then go off when the key is turned to the ON/RUN position. The fuel pump won't start running again until the motor has fired and the ECM sees oil pressure. The Momentary START side of the key switch just activates the starter. You could have a bad fuel pump regulator, a fuel pump on the way out, or a bad IAC valve for your symptoms. However without running a set of fuel pressure gauges and a computer, you'll chase your tail all day long. You can throw parts at it till one fixes the problem, but you'll waste time and money this way though. But as mentioned above, check your kill switch to make sure it's not in the KILL position.

no kill switch/lanyard

how do you pull fuel pressure when it won't run? got the gauge in my truck

talking about ON not ACC....

Depending on what type of in-line fuel filter your engine requires, could you have installed in backwards? I have accidentally done it more than once not paying attention to the flow arrows.
Another area to check is the pick up tube in your fuel tank and the anti siphon valve connected to it. Sometimes there is a screen on the pick up tube will clog up with whatever foreign objects get into the tank. The anti siphon valve will also gunk up with time. Both of these will restrict the flow especially when the engine is demanding more fuel.

Two relays on the top of the block. Mine was acting up and the fuel pump would run even after the motor was shut down. I replaced it with a Chevy part and it's been golden since. I bet that is your issue.

Start out with a test light at your fuel pump. Juice there? Yes, bad fuel pump. No, chase next thing upstream. Probably relay. Look at wire color at fuel pump and chase up to relay or fuse. Check juice on other side of relay and make sure that the 12v wire that activates that relay is hot when you turn the key on. If that's good, check the main hot wire coming into the relay. It should be hot with key on and I think key off it will be hot as well. Just keep moving upstream till you find what's holding you up.

I woulda had it fixed already damn it! Did you check every possible power wire from starting battery perko and starter? Clean anti syphon valve. Take iac off turn key in on position of valve doesn't do anything it not working. I'm on position fuel pump does prime and hold pressure check pressure at fuel rail. If doesn't come on it's a relay most likely($14) each. Cmon man fix that ****! Unless your surfing then leave it broke. Don't steal Gertrude's water breh

Finally. Thread worth a **** with some real knowledge breh...

These kinds of issues are maddening. Hang in there. I had a similar issue with my Mercruiser 350 Mag. I replaced all sorts of stuff - plugs, cap/rotor, wires, fuel filters and sensors. I bought a code reader, but unfortunately it didn't really offer any clues as to what the issue was. I was getting so frustrated that I was having visions of hosting a grand boat burning party. Then one day while we were stopped to let the kids swim I crawled under the dash to poke around. I discovered that the screw on the hot post of the ignition switch was loose. This created an intermittent connection. I tightened the screw and have been fine since.
Do you get an alarm or beeps under the dash when it's acting up?

startup beep isn't the same as it was. It had a nice loud beep after everything powered up, 2 seconds after key on. Now I get this weird chirp like it beeped with limited current. I suck at electrical gremlins like this. Gonna put a wrench on the battery terminals and look under dash for anything suspicious. all gauges, PP work flawlessly.

Just remember when you find that loose "hot" somewhere I told you August 16 to check all your hots. Lol seriously I'm willing to bet you got a loose 1 somewhere. Dash. Battery. Engine. Perko. Check them all

I thought Hot and Loose was a good thing?

Oh wait... :D