02 challenger 240 merc EFI

[A4effort]

Try not to be long winded, but could use some direction. Boat skips , sputters when accelerating and dies at the higher 3 to 5k rpms. Starts right back up instantly and will idle and run at low rpms , but as soon a you throttle up it is slow out of the hole, a split second surge of power and it shuts off like you turned the key off. Starts right up every time. Changed low and high press fuel pumps, port and starboard side temp sensors, pulled anti siphon valve out, checked fuel lines for cracks, checked screen on Sending unit in gas tank, both tank and screen clean. Ran some quicksilver fuel injection cleaner through it. New plugs and fuel filters / water seperator. Some days it will run ok, sputter but not stall and top speed is 35 according to dash speedo. Seems like a fuel issue so I replaced / rebuilt all basic fuel stuff and still cutting out on me. Any suggestions would be great

 

[Andy4k6]

Just realised this is an efi engine,

I'm not well up on boat efi, you may get a better answer in the 4 stroke forum.

However I would guess you will need to get the boat plugged in and fault codes and live data checked assuming this is possible.

Andy

 

[A4effort]

This is a 2 stroke EFI, and it's my understanding that not much can be pulled from the ECM as far as data goes but I guess that's my next step, to bring it in. I've heard a lot about a throttle guardian reeking havoc but either mine has been removed or I just can't locate it. The split second surge before it quits leads me to believe it's fuel related but I've changed all pumps. the only sensor I haven't changed is the temp sensor by the ECM....my buddy says put a rag in the gas fill and light it, that will fix it......

 

[Dr Honda]

This is a Mercury boat. The guys here dont' know anything about it. I'll move it to the proper forum.


The Starbord side temp sender have nothing to do with the control on the engine. The Port side does... but it's only a "Fuel Trim". SO... it doesn't effect full throttle fueling. The TPS is the same way.

Since you say it feels like a switch is being thrown... I'm going to say it's electrical. AND... since it's at the magic 3500 point... we need to find if you have a throttle Guardian.... and the KILL IT !!!!!!!!!!! It's a box that Mercury hooked to our boats to limit RPM's when in neutral, or reverse. It's not really needed... and it causes issues just like this.


So... look in the helm, and see if there's a black box with only a few wires. (purple, black/yellow, red, ect) if you see it... cut the black/yellow wire, and tape the ends.

 

[A4effort]

Thanks so much for responding! I looked under helm, stuck my head all the way in and looked down the side of the boat and nothing. Is there a spot near the motor where they put it?? I cut the black and yellow to the rev limiter but no luck / no change

 

[A4effort]

Man I tore this boat apart, no guardian. pulled up a pic online so I know what to look for. Looks a lot like the rev limiter and the EFI control mod. looked all through helm and engine bay no luck.

 

[Dr Honda]

ok. When they start to go bad, they cause random issues. But since they were expensive, and not really needed... a lot of the boats by now have had them removed already.

So now, we need to do a little investigating.

1) Fuel: We need to get a fuel pressure gauge on the regulator, and watch it as you run the engine. The pressure needs to stay up around 36 psi.

2) Ignition: Get a couple in-line spark testers, and watch the spark with the engine running.


Both tests need a load on the engine... so that means in the water. And you will obviously need a helper. (Someone to watch the engine, an someone to drive)

 

[A4effort]

Ok, I will pick up a fuel pressure gauge. Can I use my timing light? I should be able to clip the light on each wire and watch if it drops while the boat is moving??? I'll try this after work and report back

 

[Dr Honda]

An inductive light may be OK. Just watch close for dropped spark when it started to cut out. And needless to say... you will have to check each wire.

 

[A4effort]

On the water now and fuel press is good 35psi at all rpm with no bleed off after 3 min, spark not so good ... At 2000 rpm I loose (facing the ECM) top left spark and second one from top on the right bank...

 

[A4effort]

Just looked at another thread and according to the info you posted , the firing order if you looking at the front from the transom on my model #S240J30YS
12
34
56
So I am loosing spark on 2 and 3 so most likely it's wires or coil because 1 and 4 might be the trigger and 1,2and 3 might be a bad diode in 4,5,and 6 - (balanced for charging)

 

[Dr Honda]

Yep... check your coils. One may be bad. 1,2,3 balance each other.

 

[A4effort]

Ok, so I got what I thought was a good deal on new OEM coils so I bought 2 for $128 and replaced both. It did the trick! Runs great now, no more cutting out. A huge thank you to you Dr. Honda for your direction. I've been through quit a bit with this boat since I got it 3 months ago. Replaced the interior, installed a bimini, did a bit of motor work, repaired the fuel gauge and more... I read threads all the time in this forum so hopefully I can give back

Sincerely..thank you

 

[A4effort]

Back at it...boat ran great next couple times out. Decided to sell it while it's running good and get something bigger. Took it out Sunday and at first throttle up it quit at about 4500 rpm. Started right back up and ran fine for about 30 min until we reached our destination. Spent a few hours on the island and headed back. Boat quit three times on the way back. Mind you it's still 100 times better since I replaced two coils, but I can't sell it like this. I know that in automobiles, when one coil goes, the others usually are not to far behind so I ordered a couple more coils as a knee jerk reaction. My question is there a thread with a coil testing procedure? Am I on the right track?