TPS issue

[Coastiejoe]

I am posting this on behalf of member Jrosetti. He joined today and is not able to post yet.

I have a 2000 seadoo islandia with a 240 merc. Just replaced the motor and am trying to work all of the bugs out of it. I sent the computer off to have it tested, all is good. just replaced the air temp sensor, checked the head temp sensor, all are good. Problem is I cannot get any adjustment out of my tps. The input voltage to is is 8 volts and the output stays at 3.8-4.2 volts no mater where i turn it. If i remove it and put 12v to the input, the output works like it should. .1 idle to 7.6 wot. Please help, is my tps bad, or do i actually have an input voltage problem. I know the input voltage comes from the computer, but I just had it tested.

 

[Dr Honda]

When you tested the TPS... did you disconnect the port side temp sender??

 

[jrosetti]

Yes I did shoot wires with temp sensor disconnected.

 

[Dr Honda]

At this point... I would say to have a merc dealer check it with the DDT unit. OR... disconnect the TPS, and just check the resistance. But, since you are getting an aftermarket ECU... please give us a little feedback on how well it works out. We all hate how expensive that stupid TPS is, and I've tried to find a replacement for the past 2~3 years.

If possible... let us know who you are buying the ECU from, and how much it is.

 

[jrosetti]

I am getting it from brucato inc. They have a really good website. My stock one I'm selling for 1000. New one is 1150. And no tps sensor. So I am actually only out 150 instead of the 500 for a new tps.

 

[jrosetti]

got the new computer installed tonight. I need to retime it. figured the guy that had it before me used the timing to compensate for the bad tps. what a screwed up motor. I will time it in the morning and head to the lake and test. the new computer is about half the size of the stock one. its really nice. Plug and play. you can remove the cover and have some adjustment of how it performs.

 

[Dr Honda]

Nice.

Post some pics, and give us a ride report when you get back.

 

[jrosetti]

OK, got the new computer installed. Its tiny. looks great, and wow what a difference. you get five different fuel adjustments, etc. It has a lot better whole shot, and the motor sounds great, not only that you do away with the tps and map sensor.

I have one problem left to fix on this boat. Every problem you could have on a motor i have had and have delt with them one at a time. Now is has a new computer and all new sensors. I had this problem from the start. I cannot get it over 5300rpm at full throttle. I am pretty sure it is a mechanical linkage problem. I have linked and synced everything, timing looks good. it scoots right up to 5300, but that is it. on the main throttle arm on the motor it is getting maximum through. I am wondering if it is the linkage arm from the main throttle arm to the cam that is giving me the problem. Im not sure how far the roller is supposed to ride up the cam. Im wondering if its not opening up the second set of butterflies on the injection unit enough. please help. I will try and get some pics of the computer posted. wow what a difference. oh and if you do put one of these computers in, you either have to build a blank off for the old tps sensor hole for just install the old one, but don't hook it up like i did. it ran like crap before i noticed what i did.

 

[Dr Honda]

The butterflies aren't progressive on the 240 engine. They all open together. Each one feeds a cyl.

The 4 basic things that will keep you from reving up are...

1) Butterflies not opening all the way.

2) Low ignition timing.

3) Low compression.


Personally... I'd start with a compression check, just to make sure the engine is healthy. you want to see 125 PSI or better.

 

[jrosetti]

new powerhead, it only has 6 hours on it. i am pretty sure the butterflies are progressive on this one. the primary two at the bottom open first. the linkage to the top two has a slot in it so it has to travel to the end of the slot for the secondaries to start to open. timing was set at 6 btdc at idle and full throttle was set at 26 btdc. that is what the m2 manual said. am i wrong.

 

[Dr Honda]

new powerhead, it only has 6 hours on it. i am pretty sure the butterflies are progressive on this one. the primary two at the bottom open first. the linkage to the top two has a slot in it so it has to travel to the end of the slot for the secondaries to start to open. timing was set at 6 btdc at idle and full throttle was set at 26 btdc. that is what the m2 manual said. am i wrong.

OK... you are right. I had a different engine on my mind. But, the logic is still there. Verify that they all open all the way. I know you were asking about the roller and the cam... but just reach down, and try to open them more.

As far as being new, and low hours... I don't care. Check the compression. I can't tell you how many engines I've seen fail, when new. OR... if the cyl's didn't get chamfered correctly, you could have cracked the rings on a piston or 2. In turn... loosing compression.

Also... if you have a cyl not fireing... it will run well... but won't give full power. It's easy to tell really. Pull the spark plugs, and look at them. If you have one or two that are clean... that's the cyl that's not fireing. The other way is to start it, and let it idle for a few seconds, and shut it off. Then feel the spark plugs. If you have a cold one... that cyl isn't running.