View Full Version : Help Please, Motor at half power...???

07-05-2008, 11:47 PM
Hi, I have a 2001 moomba mobius with the 5.7 indmar. A month or so ago I was finishing up a day on the water when my boat all the sudden lost a lot of power, I thought at the time I was running out of gas, but made it in... The next week only a hour into the day it did the same thing. This time i figured it could be water in the gas. It was not, I had replaced cap, rotor, plugs and wires at the begining of the season, so I didnt think it was any of that. I went back the nest week with a new ignition module installed thinking that was it, but no luck... I have since replaced coil, cap, rotor, wires, and map sensor... No change.. I was a car dealership mechanic at one time but guess this is over my head. I just wanted to stop in here and see if anyone else had ever had this same problem and what it ended up being. I have flashed my ecu for codes and they are none.. The boat always runs great for 10min or so then just acts like it is starving for fuel, which is what I think is happening "through some type of electrical problem"... even though one of the first things I did was check fuel pressure during the porb, It was great so that's not it either. I can move the throttle to all positions, start and stop, with no changes out of the boat... I can cut it off then back on and most of the time it acts great for a few minutes then starts the problem again... No smoking or backfires. If anyone has any ideas please chime in... When working at a ford dealership I nearly never heard of a ecu having to be replaced, so I have to purchase one and it not be that.. Thanks for any help lended.

07-06-2008, 01:27 AM
Only idea I have is fuel lines. Some of them get softer as they age. On my old outboard there was a piece of line right before the fuel pump that had about a 180 degree turn and a bit of a twist in it. When the motor warmed up and you put a heavy demand on it the line would suck closed and shut you down completely. It would restart immediately, run great, then die when you got on it again. Took me a while to find it but once I replaced the piece of line the problem was solved. This might not be your problem but it might point you in the right direction. Good luck!!

07-06-2008, 02:05 PM
I wish that was it, but it has great fuel pressure on the fuel rails at all times... Do these boats have a limp home mode? On one of the other forums someone mentioned a low pressure water intake switch or a coolant temp sensor puttinig it in a mode like this to avoid damage...???

07-07-2008, 11:20 PM
Well I am having a similar problem. I have an 08' XLV with the 5.7 340 w/ about 32 hours on it. I just put it in the shop so I will let yall know what I here.

07-08-2008, 10:42 PM

Call Jody at Florida Inboards in Panama City. He is authorized to do Indmar repairs and knows a ton about this engine. I would not trust anyone in Dothan to do this.

07-10-2008, 04:23 PM
Had a similar problem form a bad tank of gas. Pulled the fuel filter and blew through it backwards and all of this black oil looking stuff came out. Boat would run great, but had no power. Easy to check and worth the try.

07-10-2008, 10:28 PM
Same thing happened to me this week..couldn't go any faster than 30 mph. Changed out the fuel filter and its as good as new.

Ian Brantford
07-14-2008, 02:45 PM
Had a similar problem form a bad tank of gas. Pulled the fuel filter and blew through it backwards and all of this black oil looking stuff came out. Boat would run great, but had no power. Easy to check and worth the try.

Yep, same here. On my 2005 XLV, there are TWO fuel filters. They boat have to be checked.

This never happened with the marina's high-priced gas, but I filled up a couple of times at an independent automotive gas station while at a cottage and then... crappy fuel.

07-21-2008, 08:53 AM
2005 outback lsv. same problem, dealer ran boat with lap top connected. all indcations normal and no fault codes. they did not have a clue. also told me there was no inline fuel filter. finally found it behind false panel in rear ski locker attached to transom. replaced filter runs great.

NH Moomba
07-21-2008, 02:32 PM
You might check you pump impeller. My 2000 Outback fuel injection system shuts the motor to "limp home" power when it senses an overheating condition.

07-28-2008, 08:13 PM
You may need to check the screen on the fuel pump. My Outback had the same issue, it would run great until I had a skier on the end of the rope, then it wouldn't pull at all.