Phazer engine HELP needed, non-sled application.

[Bullnerd]

Need some serious help from someone that really knows there stuff with the phazer engine. You guys are my only hope. I cant figure it out.

I have a 2007 phazer 500 engine that is mounted in a small offroad racecar. Anyone remember the Mickey Thompson stadium races from the early 90s? This is one of them.

Here is a link to the build thread. There are some pics there. http://www.minibuggy.net/forum/projects ... -post.html

So my problem.It will not start without opening the throttle just a small amount. I know thats not good. I've done a lot of reading on this site and know thats not right. It then will not idle. If I keep the throttle open slightly i can keep it running but it takes more and more throttle to keep it idling and eventually just fouls the plugs. The harness has been modded by a guy that knows them pretty good, (K-fab,hes a member here) he's done multiples and mine was tested on a running engine. The engine came from a running sled and a trusted source. The throttle/grip heater switches have been removed so I cannot clear past codes or test the items you need those switches for,coils,injectors,etc. I will be adding those back shortly though. No check engine lights flash or codes on display while engine is running. Everything checks out ok when I run the diagnostics that I can. I had the injectors proffesionally cleaned by a bike shop. The throttle bodies have been taken apart and cleaned. I have 42psi of fuel pressure at the rail. Engine cranks fine(forget the RPM).

When i check code 24 in the self diagnostics it says "throttle open" or "ON" I do not understand this? Where does it read this? I have plenty of throttle free play and the TPS checks out ok (range wise) on the diag.

OK,thats all(HA) that I can think of right now. Sorry for the long read. Hope someone can help.

Mike

Heres a pic of the car

 

[cannondale27]

It reads it at the throttle position sensors. Specs are in manual. Can check it with a OHM meter. Would make sense something in that circuit is the issue.

 

[Bullnerd]

So the TPS can still be bad even if the self diag. shows it reading the proper range.

I guess thats (range) different than reading with a meter?

Is there a way to check it without the fancy adapter Yami sells? Poke the wires?

If the ECM thinks the throttle is "on" (does this mean open?), will it keep it in cold start mode? Because thats exactly what it seems like.

Please tell me its the TPS!

Thanks for the help.

 

[Bullnerd]

It looks like the TPS is bad, providing I'm checking it right.

Whats a good source for Yamaha parts?

 

[cannondale27]

4-6k ohms blue and black wire is what manual says. Normally you would check the range and see that it is progressive but I dont see that test in manual.

 

[cannondale27]

Kind of confusing. Here is from 07 manual for setting it. It is assuming it is good and you would do this test with it plugged in. I would check the range also with it uplugged and using a Ohmmeter between the yellow and blue black pins is sensor itself. They dont go bad very often.

 

[Bullnerd]

Thanks for the help Cannondale.

Yes it is confusing.

I rechecked the TPS I had my meter set on the wrong scale first time around.

I think its bad.If I probe across the pins spec'd in the manual its should max out at 4-6 like I said earlier. Its pinned at 5. Meaning it doesnt go through the range from 0-4,6...its always on 5. I'm guessing that why the self diag. says the throttle is on/open even when its not.

If I probe the other two pins,it cycles fine, 0-5, this is probably feeding the self diag. that shows the "range" is ok.

So, when I try to start it, the ecm sees full throttle but is also in cold start mode. Thats why when I keep it running it smells and runs super rich. I said it was blubbering earlier.

The range scale on the self diag. was really throwing me off, I knew to check the voltage on the TPS but forgot about the resistance!

I think this is the problem and will be looking for a new TPS.

 

[Bullnerd]

So any advice on where to buy from?

 

[rat4020]

Ya Bull I fighured one of the sled gurus would chime in for some assistance .. Cool Oh and welcome to TY4stroke .

 

[cannondale27]

Yamaha dealer. I still am not convinced this is your issue since you are seeing it go through the range. If it helps any the Yellow wire is the one I hooked my PowerCommander to for throttle position.

I am thinking the On you are seeing is the throttle overide circuit. Have you checked that it is working properly.

 

[yamahas]

Yamaha dealer. I still am not convinced this is your issue since you are seeing it go through the range. If it helps any the Yellow wire is the one I hooked my PowerCommander to for throttle position.

I am thinking the On you are seeing is the throttle overide circuit. Have you checked that it is working properly.

This is along the same thoughts I am having.

 

[UP bushman]

Hey guys I have an 07 MTX my reverse won't work sometimes. But when it won't go into reverse I cycle key with throttle open and start then it works. My throttle positioning sensor is in range as well with proper ohm readings. Must be an issue with bad design they changed it on the 08 and up sleds. Still would lean towards that.

 

[Bullnerd]

Yamaha dealer. I still am not convinced this is your issue since you are seeing it go through the range. If it helps any the Yellow wire is the one I hooked my PowerCommander to for throttle position.

I am thinking the On you are seeing is the throttle overide circuit. Have you checked that it is working properly.

Thats the thing,it doesnt go through the range between the wires spec'd in the manual,Its pinned at 5. It does go through the range between the Yellow wire and the black wire.

Is that the TORS? No have not checked anything with the TORS. I am trying to find someone that can check the throttle "on" thing for me.

 

[Bullnerd]

Ok,I had a guy with a similarly modded wire harness check his Diagnostic screen and his says "on" also. So Canondale ,your probably right. I know nothing about the TORS ,but its not an issue on the other buggy as it runs fine.

Any one have a TPS laying around they can put a meter on?

 

[Mooseman]

TORS shouldn't affect it when starting so I also think it's the TPS. I have a couple sleds apart in the garage but kinda late right now to check. I'll try and remember to check it out tomorrow.