Indmar 340 Assault only 2700 RPM at WOT

[Jhendrix39110]

I have a 2008 Mobius LSV with Indmar 340 Assault. The max RPM is 2700 at WOT. It will surge up to 3400 but only for a second or two. I have replace fuel filter and checked fuel pressure. Also installed new spark plugs and cleaned K&N filter. What should I try next?

[Fastest1]

Sounds like a fault code is limiting it.

[Jhendrix39110]

Thanks. How do I find the fault code?

[trayson]

Plug Wires, Cap, Rotor, fuel filter!

[Jhendrix39110]

Thanks. I replaced rotor and cap in 2017 so hopefully those are still OK? I haven’t replaced the wires. Can I buy those at an auto parts store? Or do I need to order those? And where do I find the part number?

[trayson]

Thanks. I replaced rotor and cap in 2017 so hopefully those are still OK? I haven’t replaced the wires. Can I buy those at an auto parts store? Or do I need to order those? And where do I find the part number?

Personally I think that the Cap and Rotor are cheap enough that they're worth replacing. By the time you pull them off, it's silly to skip out on like $20 in parts. They corrode and cause issues. I use the cheap aluminum ones from the auto parts store and replace every couple years.

As far as plug wires, You might check Bakes. Technically, wires from a car would work fine. However, the lengths of them is going to be different as the distributer is typically located in a different spot on a car as it is on the boat. And if you have the 340 CAT ETX like I do, the clearance is TIGHT on the distributer to the manifold so having the correct angle of the ends on the plug wires is important for fit. And the good ones are numbered making things that much easier. They're expensive for what they are, but I haven't found anything for a lower price that doesn't have drawbacks.

I have a 2008 with the 340 cat etx and it's a prissy little Bi*** about cap/rotor/plugwires... Also swap out the fuel filter. it's cheap and easy. But easiest to find the fuel filter online because the hose size is bigger than cars...

Sure, I throw parts at my boat to deal with problems (I've had your symptoms before) and I can't say with absolute certainty what the EXACT solution for a given problem was, but I do know that even throwing parts at my boat, it's still been cheaper than a single visit to the dealer.

[Jhendrix39110]

Will give those a try and let you know how it works out. Thanks again!

[Fastest1]

I have a few boat dealers around me that will scan the codes, usually on Saturday. Some will charge a fee, some dont.

[Jhendrix39110]

Thanks for the suggestion. Does the Check Engine Light need to be lit up in order to show a fault code? It is not lit so just checking if that is required.

[Packman]

Change the ignition module under the distributor. Had the same problem replace everything talked to Larry (Engine Nut) told me to replace it got it at the local NAPA store he said it wasn't special for a marine distributor.

[JHutch]

IF they have not been replaced its probably the post Cat Sensors. They no longer make them so you have to cut the wire and put a resistor in place to take it out of limp mode.

[treverspence]

Do you have a part number for the ignition module. I have a 04 XLV I'm needing to change the module. I wasn't sure if it had to be marine or not.

[secondsupra2004]

Do you have a part number for the ignition module. I have a 04 XLV I'm needing to change the module. I wasn't sure if it had to be marine or not.

I just replaced the ignition control module on my 04' Supra with the assault 320 TBI. I bought it from Inboard Direct Online, and when I received it the part number crossed over exactly to a Standard Ignition Products module # LX-384. I bought one of those as a backup to carry in the boat as it takes about 10 minutes to change it. Got it from Rock Auto for $47.00 I believe.
This is the same module that fits most of the Mercruiser, OMC, Volvo 5.7 engines. I have been told by several sources it is not exactly the same as an automotive module, but I didn't design it so I can't verify that one way or the other. I didn't want to take a change and damage the ECM if it wasn't designed for it.

[player1986]

wires from a car would work fine