View Full Version : '96 Maristar 225 VRS bogging down after warm

08-20-2012, 08:23 AM
I have owned my '96 225 Maristar for 6 years with virtually no problems. Last weekend while pulling a boarder, I noticed I didn't have the power I normally do. We had been driving for a good 1-2 hours with no problems when it started acting different. At idle the boat sounds great, but when I get on the throttle it sounds like it isn't getting enough gas. Sluggish or bogging down. My first thought was my last batch of gas may have been bad. I was worried that some water had mixed in the cans I use to transport it to the dock.

Here are the things I've done to try to fix it.

I have removed the fuel lines, and cleaned out the tank. It had some dirt, and enough debris sitting in the small tank, I thought this might be it. I also inspected the small screen at the end of the line, it was clean. I was able to fix my sending unit while down in this area, I found a small magnet that had separated from the float. Super easy fix for anyone that has a gas gauge that isn't working.

I replaced the fuel filter. I know it is at least 6 years old, maybe older.

I replaced the distribution cap and rotor. This was very corroded, and at least 6 years old. I thought for sure this was it.

I replaced the spark plugs, these didn't look very good either.

After all of this, the boat still had virtually the same problems. After much more testing, I now have more observations. Boat never has any troubles firing up. When cold, I can come out of the hole very well, I get up to about 30mph before I "feel" or hear anything different. Once I've gone about 1 minute, I start to feel sluggishness, or what I would call bogging down. Once it's warm, I can get out of the hole, but it stays sluggish, and the further you put the throttle down, the more you can feel this sluggishness. After the boat has been running for 5 minutes or so, it will now start idling poorly, and generally sounds much worse. By then I have shut it off, and put it back on the lift.

My next thought is the fuel pump. I would love to hear others thoughts. Thanks in advance.

08-20-2012, 10:20 AM
In my experience anytime you're dealing with EFI(I assume it is), always verify fuel pressure is correct before anything else. Sounds to me like the engine temp sensor for the ECM is possible bad. Engine warms up, but sensor tells ECM motor is still cold, so the mixture stays rich(virtual choke) hence the sluggish running condition. You said the spark plugs didn't look good, black and sooty? This would indicate a rich mixture, which shouldn't happen with EFI. Pull the engine oil dipstick. Does it smell and/or taste like fuel? Over rich will quickly contaminate the engine oil, and be an obvious sign as well. I'll stop here before I get too far ahead of myself and give you a chance to respond.

08-20-2012, 10:47 AM
I'm in the zone so I'm gonna keep going on this one for a minute. Once again I'm assuming it's a GM EFI motor. GM calls this sensor a CTS(coolant temperature sensor) they used this same sensor from 1985 damn near up to present day from TBI to port motors, Vortec, etc.... I have seen this same problem more than a few times in the automotive world that I'm willing to bet on it. The best part is it's cheap! GM or NAPA, you shouldn't payIt more than $19.95 for it. Now days in the automotive world, replacing it is part of a regular tuneup. On my PS205, it's located on the drivers side, just under the exhaust manifold, screwed into the block. Brass colored, 3/4 inch six point socket(I think, can't remember for sure) two wire plug. It's a non marinerized part so don't let anyone try and sell you some megga dollar boat version. It's worth the gamble because it's so easy and cheap to try unless anyone else has an idea. Or, I could be wrong. Looking forward to your feedback.

08-20-2012, 10:56 AM
Is it an lt1 engine?

08-20-2012, 11:17 AM
EFI, yes. LT1, no. This is the standard engine of that year, I think it is 350hp.

Thanks for the feedback. I'll be out at the boat this afternoon, I'll check for the gas smell on the oil dipstick. I'll try to locate this CTS sensor.

I say the spark plugs didn't look good...I also don't really know what I'm doing. I know they are least 6 years old, so I figured it wouldn't hurt to get a new set in, for less than $30.

09-03-2012, 08:51 AM
tmony69. Thanks for your time and input I really appreciate it. I'm very thankful to have this forum as a resource.

I've located and replace the CTS. This didn't fix the problem, but it was old, and I don't mind replacing it. Total cost $19.

After driving the boat a few more times for short periods to test it, I have a more observations. It always fires up, right away, and idles fine. When I come out of the hole when the boat is cold, I get up to speed, but I can get it to have the bog problem, but it happens at a higher RPM. It happens at about 3200 RPM. The more you drive it, maybe 2 more minutes, this bog down happens at lower and lower RPM. 3000, then 2800...and it keeps going. But I haven't tried to drive it much more than a few minutes, before shutting it down.

The term "bog down" may not be the best way to describe it. It feels like a suck or a vacuum effect on the gas. You push down further, and it decelerates rather than accelerate.

Any other ideas?

10-04-2012, 02:09 PM
I'm still waiting for my mechanic to come out. He's only put me off for 5 or 6 weeks. Anyone else have any ideas. I've replaced everything I can, and the problem is exactly the same. I'd consider changing out the fuel pump on my own if I could. But do fuel pumps have problems like this? They work fine at 2000 rpm, but struggle at 3000, and then minutes later struggle at 2000?

Any ideas....OR does anyone have a great mechanic in Chattanooga TN? I am certainly willing to pay good money to get this fixed.

04-05-2017, 11:31 PM
Man I know this is digging up bones here, but you're describing my boat to a tee. What was the final outcome?
Thanks, Skye

06-10-2017, 11:20 PM
Yeah my boat too.....I am curious what the mechanic said.

06-21-2017, 09:36 PM
Me too! What did you find out?

07-11-2017, 07:31 PM
I'm having the same problem with the lt1 engine. Any luck on finding out what it is? Been in the shop twice and sensors have been replaced and still nothing has changed. So frustrating

07-12-2017, 05:54 PM
For all of you asking what his problem ended up being, check the fuel pressure. This pump and line setup has a tendency to get plugged up at three points: the screen in the tank, the antisiphon valve on top of the tank, and the fuel pump inlet. This is of course assuming you have already changed the filters. Key to diagnosing these is check the fuel pressure, then go from there. Generally speaking when they sit some of the debris falls off the blockage, then when you restart it runs ok for a little bit until the debris plugs it back up. If that doesn't correct it feel free to post a new thread and there are some great guys on here that can help diagnose it. Good Luck!