98 SRX 700 Servo motor/controll problem

Y

Yuriy

New member
Joined
Nov 6, 2007
Messages
81
Age
42
Location
Illinois
Well this is starting to get challenging. I started the sled reved it down to 900rmps the motor retracted I made my mark and start adjusting the valves. After I was done with adjustment I started the sled and observed the motor (servo) movement as I was accelerating. Everything was cool even the water temperature light came on and blinked 3 times at the start up. Then the things started getting strange, as I was giving the acceleration to the engine the servo was adjusting not as smooth as it did in the beginning and the light was trying to blink somewhere within 3-4K rpms. After running the sled for couple of minutes I noticed that the servo motor was moving less and less with me reving up the engine until it (servo) finally stopped responding to any throttle manipulation. The only way to get the servo to move was to shut the sled off and let it sit for a few minutes than start it. Since I observed the servo motor movement I concluded that this might be not a servo motor problem but a servo motor control problem. I checked the connections between the servo and the computer they were fine. The manual suggested checking the servo motor coil continuity/resistance. Recommended resistance on the magneto side according to the manual is 1.472-1.799 at 68F the reading that I was getting in my cold garage on the warm sled was between 1.8-2.0 and what significant is as the engine was cooling down the reading was getting lower (remember starting the sled wile its cold the servo was working fine, it craps out when the engine has been running for a wile). Another thing that was not clear in the manual is the check of the DC regulator to which the connection (resistance of which I was checking) gets connected to. Basically the other side of the servo motor coil located in the magneto. I didn’t get any reading on checking the connection on the DC regulator side, got open circuit is it normal? To sum this up I think ether the servo coil is out of specification an as the motor gets warm the coil gets more and more out of spec thus preventing the servo from operation, or the DC regulator is toasted (does anyone know how can I check it), or the computer is done. Any ideas?
 

I think the drum that the cables are on will sometimes jump back and forth but when you rev up the engine to 5,6 or 7 thousand rpm you'll see the drum really turn to pull the valve open.
 
The problem is when the engine warms up the servo stops moving completely. As I follow the manual the servo gets its controll signal from computer which in tern reads the engines RPS through the magneto coil and for some reason DC regulator is included in the shcematics. Do you know how I can test the DC regulator? What do you think about the resistance on the magneto (servo coil control) and it's increase with the engine warming up
 
Im sorry Im not very up and all that ohm's stuff.
Let me do a little looking and get right back to you.
Its only 10:30pm where I am.
 
Thanks for the thread, this was the way I read it from the schematics. Sounds like I have one out of 4 failures: 1 magneto coil that send the signal to the CDI, 2 CDI itself, 3 DC regulator, 4 connection. We can rule 4 out since the motro does move there is a really thin chanse of any connection being loose. There is no way for me to check the CDI without having another CDI that I can drop in for testing. There is no clear way that I know of to check the DC regulator (it's involvment in the controll process is questionalbe) The only thing left is the magneto coil is giving me higher reading than the manual calls for specially when the engine is getting warmer which makes sence since hotter the ambient temperature more conductive the coil, so when I start the cold sled servo works fine (the coil is cold and the reading is on its high limits) as the motor heats up the coil it becomes more and more conductive falling beond the top limit of its conductance thus preventing the servo from movment. What sucks the most is that the only real way to check any of these parts is to drop them in one by one.....
 
Hmmmm,does it open when you drop the rpm's below 900?
Do the cables and valves move freely?
I just can't see any wiring going bad on you. When did this start to happen?
 
When the sled is cold the servo works like a champ dorp the RPms below 1000 and it opens all the way up. As soon as the sled warms up dropping the RPMs doesn't help the servo responds weaker and weaker and eventuall stops. I just went down to the garage and measured the resistance on the servo coil the reading is 1.7 within the range. The sled has been sitting for about an hour and I bet if I was to start it the servo would work fine. I have a stron feeling that I damaged the servo coil when I was trying to use "home made" test leads. I connected the two reads to 12V and the black to 0V. GD manual didn't show any other devises being on that test lead. After having this discussion in hear someone said that the leads also include a resistor which limits the current. Wiring the 12 V straight without the resistor might have damaged the coil. Do you have the test leads, have you ever seen them, do they have a resistor anyweare or it's just the wires running stright through? Please let me know.
 
I have always tested my valve bt dropping the RPM's.
If you think you fried the servo look in the used section and see if antone is selling one. I know MRviper thinks in this case your CDI is gone. there is a CDI for sale from a guy in Illinois.
 
Thank you for your help, I'll try to work something out wher I can get the CDI, DC regulator, Servo coil (magneto coil) all at onse, use the parts that I need and return the rest for a refund. Thanks for your time, If you think of something on this subject drop me a line.
 
You must log in or register to reply here.


Back
Top