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jeffw
01-24-2012, 01:13 PM
I have a 98 maristar 225 with the 5.7 engine that i purchased this summer. i had the dealer go through it since it had been sitting for 5 years and they did the normal jobs needed plus send the fuel injector unit for overhaul, drain and refill the gas, change filters etc.
My question is why would it run initially as it were loaded up then clear itself each time i take it out, it starts fine and idles but the initial run is sluggish and there seems to be excess fumes on the platform while idling all the time. Im going to try octane or fuel additive and see if it changes.

mikeg205
01-24-2012, 01:40 PM
98? check the ecm....

jeffw
01-24-2012, 03:16 PM
Can the ecm be adjusted?

j.mccreight@hotmail.com
01-25-2012, 03:56 PM
Can the ecm be adjusted?

No the ecm can't be adjusted, I would check the engine coolant temperature sensors, and the thermostat, if those are out of specification the engine could run rich...

mikeg205
01-25-2012, 04:06 PM
oh...now i wonder if the thermostat is missing.... good point j.

obsessed
01-26-2012, 03:44 AM
What would the thermostat do? Would the engine run rich if the engine temp was too low?

I have an MCX that stutters when I acceleraten from idle, I know my thermostat is missing, but I live in a hot climate and my dealer said it would be fine. I have installed some in-line mufflers recently, and noticed this problem after that, but now cant remember if it was there before the install or not.

JimN
01-26-2012, 08:22 AM
What would the thermostat do? Would the engine run rich if the engine temp was too low?

I have an MCX that stutters when I acceleraten from idle, I know my thermostat is missing, but I live in a hot climate and my dealer said it would be fine. I have installed some in-line mufflers recently, and noticed this problem after that, but now cant remember if it was there before the install or not.

The thermostat maintains correct coolant temperature, so the engine can run as efficiently as possible. If the thermostat is missing, the temperature will be whatever the water temperature is, plus whatever heat is extracted from the engine as the water passes through. A cold engine is an inefficient engine.

Your dealer is wrong.

obsessed
01-26-2012, 11:56 AM
Makes sense. Will install one soon enough. Thanks.

jeffw
01-26-2012, 02:49 PM
Thanks for the input, my temp. guage doesnt seem to read that accurate, maybe theres more to it.

Hollywood
01-27-2012, 06:54 PM
Well, what does it read?

jeffw
01-28-2012, 09:41 AM
The local dealer said it was inop but I notice it just barely comes up while in use. I purchased a new thermostat and will replace it and check the connections and see what happens.

JimN
01-28-2012, 10:30 AM
The local dealer said it was inop but I notice it just barely comes up while in use. I purchased a new thermostat and will replace it and check the connections and see what happens.

Check the gauge, too.

I would have a serious problem with a dealer that told me the temperature gauge was inoperable and didn't try to repair it, BECAUSE IT'S FREAKING IMPORTANT!!!!!!!!!!!!

jeffw
05-06-2012, 11:05 AM
Well I replaced the gage and thermostat and all is good now. The "rich" smell has dissipated and the boat is running better then ever.

mikeg205
05-06-2012, 11:08 AM
Glad you got it fixed... so much for getting advice from the dealer.....

JimN
05-06-2012, 11:16 AM
Well I replaced the gage and thermostat and all is good now. The "rich" smell has dissipated and the boat is running better then ever.

Did you change the thermostat first and check the gauge before changing the gauge? If not, you may not have needed the gauge at all because the problem seems to have been caused by the thermostat- it would indicate low temperature if the t-stat was stuck open and it would run rich for the same reason.

jeffw
06-13-2012, 03:13 PM
Well, the boat is not running rich but it does this...starts/idles great but during the initial run at 2-3k rpm the engine looses power with sometimes a faint backfire. After a few run ups, everything is normal and the boat runs like new. I replaced the fuel filter at the tank but also noticed one prior to the manifold. ill change that next week.

JimN
06-13-2012, 08:34 PM
Well, the boat is not running rich but it does this...starts/idles great but during the initial run at 2-3k rpm the engine looses power with sometimes a faint backfire. After a few run ups, everything is normal and the boat runs like new. I replaced the fuel filter at the tank but also noticed one prior to the manifold. ill change that next week.

I would check the timing and make sure it's at 10BTDC with the ECM in diagnostic mode. The procedure has been detailed here many times- look for tips for using a paper clip. You can use a scanner, too (or, you should be able to). If you plug the scanner in and the timing light is stable, go ahead and check the timing. If it's not stable, put it in diagnostic mode. This is not optional- it has to be in diagnostic mode when setting the timing.

Look at the pickup coil for the distributor and make sure the distributor's base is grounded well (as in, perfectly). The distributor and IC module both get their ground through the base.

How old did you say the plug wires are? If they're older than 5 years, replace them. You may be experiencing cross-fire.