Tired of restarting

I have a 1995 MC205 with a TBI 350. Been chasing a problem I just can't figure out. With the boat cold it starts and runs fine. After 30 minutes or so of pulling a skier I loose power above around 2500 RPM's but runs just fine below it but not above. If I turn off the engine and restart it immediately it runs like a champ for another 15 - 30 minutes then it happens again and I have to restart. I've put new plugs, new coil, new wires, new cap, and even replaced the ignition module but nothing has effected the problem. Monitored my engine temp and it's not even close to over heating nor do I have transmision problems. I checked the temp overheat sensor and temp guage sensor - both seem to be okay but not really sure how to verify. Oil pressure is also fine. Seems like it's getting into limp home mode but never seeing the overtemp light go on. Any ideas what it could be? Suspecting problem might be in the computer, just guessing now.

[ahhudgins]

Before I started randomly swapping parts out, I would get one of the code readers so you could check the ECM for fault codes. It beats just guessing. Engine coolant temperature sensor (or wiring) could be faulty/intermittent. If I remember correctly, my 95 has 3 sensors: Two on the intake manifold, one for the gauge, one for the idiot light. The sensor for the ECM is in the block under the exhaust manifold.

http://www.michiganmotorz.com/codema...er-p-2459.html

[mikeg205]

Originally Posted by ahhudgins

Before I started randomly swapping parts out, I would get one of the code readers so you could check the ECM for fault codes. It beats just guessing. Engine coolant temperature sensor (or wiring) could be faulty/intermittent. If I remember correctly, my 95 has 3 sensors: Two on the intake manifold, one for the gauge, one for the idiot light. The sensor for the ECM is in the block under the exhaust manifold.

http://www.michiganmotorz.com/codema...er-p-2459.html

+! on this.. you'll drive yourself crazy without it... and $59...is a cheap way to get read out on the engine...

Please keep us posted on the diagnosis and repair...

[thatsmrmastercraft]

I'm not an expert on the newer stuff, but it sounds like a fuel delivery problem to me.

[ahhudgins]

Originally Posted by thatsmrmastercraft

I'm not an expert on the newer stuff, but it sounds like a fuel delivery problem to me.

Hopefully his 205 isn’t like 95 Maristar and has no Schrader valve. Kind of makes it hard to check the fuel pressure. I’m trying to find someone who can fabricate a new fuel line with the valve.

The "newer stuff" is great until it screws up. Discovered that my Maristar will not rev up over about 2200 RPM in neutral. MC has no idea why but I found two other guys on this board with the same boat and theirs does the same thing, so it must be programmed in the ECM. Haven't seen a 95 Prostar with TBI that does this.

[JimN]

Originally Posted by BartVal

I have a 1995 MC205 with a TBI 350. Been chasing a problem I just can't figure out. With the boat cold it starts and runs fine. After 30 minutes or so of pulling a skier I loose power above around 2500 RPM's but runs just fine below it but not above. If I turn off the engine and restart it immediately it runs like a champ for another 15 - 30 minutes then it happens again and I have to restart. I've put new plugs, new coil, new wires, new cap, and even replaced the ignition module but nothing has effected the problem. Monitored my engine temp and it's not even close to over heating nor do I have transmision problems. I checked the temp overheat sensor and temp guage sensor - both seem to be okay but not really sure how to verify. Oil pressure is also fine. Seems like it's getting into limp home mode but never seeing the overtemp light go on. Any ideas what it could be? Suspecting problem might be in the computer, just guessing now.

The temperature sensor you need to check has one yellow wire and a black one. The other sensor(s) would be for the gauge, not reporting to the ECM.

You need to check for codes and you shouldn't just throw parts at it without knowing where the problem lies.

Check your impeller. These don't have a radiator, so they don't have a "limp home mode". If it runs sluggish and lumpy, shut it OFF, don't keep running it. If your impeller is bad, and the fact that it was OK last year or replaced it this spring means absolutely nothing.

[JimN]

Originally Posted by ahhudgins

Hopefully his 205 isn’t like 95 Maristar and has no Schrader valve. Kind of makes it hard to check the fuel pressure. I’m trying to find someone who can fabricate a new fuel line with the valve.

The "newer stuff" is great until it screws up. Discovered that my Maristar will not rev up over about 2200 RPM in neutral. MC has no idea why but I found two other guys on this board with the same boat and theirs does the same thing, so it must be programmed in the ECM. Haven't seen a 95 Prostar with TBI that does this.

OTC has a fitting that can be used for testing fuel pressure on these. It goes where the fuel filter is connected.

[ahhudgins]

Originally Posted by JimN

OTC has a fitting that can be used for testing fuel pressure on these. It goes where the fuel filter is connected.

My local auto mechanic showed me one of those in a catalog but I was hoping for a permanent fitting. You know of any logical reason they didn't put the fitting on the fuel line for a TBI?

[JimN]

Originally Posted by ahhudgins

My local auto mechanic showed me one of those in a catalog but I was hoping for a permanent fitting. You know of any logical reason they didn't put the fitting on the fuel line for a TBI?

I don't think they saw the quality of fuel dropping as far and as fast as it has. Also, the pump was right at the rear of the engine, so I'm not sure they saw much need at the time. "It only has to go 2'- what could go wrong?" may have been asked, somewhere.

OTOH, it could have been a Coast Guard thing- they don't like change or a way for fuel to leak under pressure and they probably assumed someone would damage a valve, causing fatalities.

[ahhudgins]

Originally Posted by BartVal

I have a 1995 MC205 with a TBI 350. Been chasing a problem I just can't figure out. With the boat cold it starts and runs fine. After 30 minutes or so of pulling a skier I loose power above around 2500 RPM's but runs just fine below it but not above. If I turn off the engine and restart it immediately it runs like a champ for another 15 - 30 minutes then it happens again and I have to restart. I've put new plugs, new coil, new wires, new cap, and even replaced the ignition module but nothing has effected the problem. Monitored my engine temp and it's not even close to over heating nor do I have transmision problems. I checked the temp overheat sensor and temp guage sensor - both seem to be okay but not really sure how to verify. Oil pressure is also fine. Seems like it's getting into limp home mode but never seeing the overtemp light go on. Any ideas what it could be? Suspecting problem might be in the computer, just guessing now.

As already stated, check codes and fuel pressure when it messes up to avoid wasting a lot of time and money. A code reader and a pressure gauge are great tools for fuel injection engines. The two sensors on the intake with the brown wire and brown w/black trace are for the gauge and over temp light. The one JimN mentioned is below the exhaust manifold in the block. The plug has the yellow and black wires. You can check the resistance of the sensor by cutting off the engine and removing the plug, then use an ohm meter to check across the sensor. Engine temp between 140 and 176 degrees F should read between 667 and 332 ohms. Resistance goes down the hotter it gets.