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Causes and Symptoms

6K views 23 replies 5 participants last post by  dutchturbo 
#1 ·
Hello, I'm a new owner of a 500 Turbo. I admired these from the 1st time I saw it on the cover of Cycle World. Now I finally own one with 19,000 miles.

I was told by the previous owner that the PB sensor was bad. He also said it had the stator replaced but I am getting one from Custom Rewind now. Some people....

I have learned a lot from this forum but do have some questions for the more technically savvy members. I never got the fuel system warning light on my bike and never checked the LEDs for a code because the dash never gave a warning. With the engine out to replace the stator I can see how much corrosion there is around the speed sensors. I plan to check the resistance on them today.

My bike doesn't run great below 3500 rpm and seems to load up while idling. It ran ok on the highway until the stator quit on the way home after I just bought it. Some people....

Isn't there supposed to be a warning from the Fuel System light if a sensor(s) is bad? I am hoping that a new charging system and battery will correct some of the issues before I have to start sourcing Suzuki electronic parts.

Thanks
 
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#3 ·
Not running good below 3500 rpm, is likely the PB sensor. You can replace with a used one or do the upgrade to the suzuki sensor described in this forum.

The speed sensors is your call. the corrosion is caused by a leaky mechanical seal which should be replaced if it has not been already. Then the sensors themselves, you will have to decide if you want to clean them up and reuse them or do an upgrade to the speed sensor to the LX579 as explained in this forum.

Personally, on one bike I reused them (if its not broke dont fix it approach) bike is still running fine. I am doing a second one now and I did replace them with the LX579. still in the middle of that one so cant report on results but others have had good results.

I have tagged many posts, so if you look for tags containing "johnste" it should help you find what you are looking for. other than that, the search feature is pretty good. if you have trouble let us know and we can help you find what you need.

good luck
john:cool:
 
#4 · (Edited)
I am not 100%, but I do not believe you will get a warning light on dash for everything.

When something is not running right, do not shut off bike, remove seat, and observe the LED codes. If you shut off the bike, the fault might clear and the LEDs will not display. I know this sucks, but it was the technology at the time.


Running bad below 3500 and perfect above that RPM describes to a T a bad PB sensor, so I would start with that. that is exactly what mine did. I replaced the PB sensor with a used one and bike works perfectly.

ALso, I think the PB and P1 sensors are the same, so you can look into this. I think nowadays most people are doing the suzuki sensors, unless they are looking for originality.


Sounds like you were fed crap on the STATOR. I bought two of these, ne with 19000, and one with 19500. Drove one 100 miles and the stator popped. drove the other 150 miles and that stator popped. They blow by 20000 pretty much like clock work.

I put a greg goss stator in one, and a custom rewindes in the other (not done yet) Personally, because of the failure mode I really like the custom rewinds stator. I think most have had good luck, but with the low miles put on, the world may never know. Always a big debate on the form as to wether potting is a good approach. Custom Rewind gets my vote, LOL I did a root cause on one of my failed ones and saw exactly where and how the short occurred due to a corroding insulating layer on the winding.
john
 
#5 ·
Thanks. I hope to have the mechanical seal and gaskets this coming week. I have access to a press so hopefully that will make quick work of the mechanical seal. It always seems to take longer to put things back together than to take them apart. I will post again when it is running and charging.

I will have some questions on how to fix the trip meter reset knob and clock set knob.
 
#7 ·
Got the engine back in and shifting. Don't think the mechanical seal liked being disturbed, even though it only was together for about 10 minutes of running. It started leaking on the reassembly as soon as the thermostat opened. It seems to have stopped now after a few heat cycles.

This bike is really testing me. It doesn't like to run when it is low on fuel. Before the reserve light comes on it will behave like it is almost empty. I pulled the strainer out of the tank, cleaned and back flushed the fuel filter. Strainer did clean up and it did seem to take a long time to drain the tank from the petcock. Very little dirt came out of the filter. Put it back together and all the symptoms the bike had of a bad PB sensor were gone? The poor running under 3000, feathering the throttle to get it to take gas, it almost idled? BUT it seems to only run on one cylinder now. Checked spark and it is good. Plugs are heavily sooted so I'm going to try new ones. The Suzuki sensor showed up yesterday. Hope to get it wired in this weekend.
 
#9 ·
BUT it seems to only run on one cylinder now. Checked spark and it is good. Plugs are heavily sooted so I'm going to try new ones. The Suzuki sensor showed up yesterday. Hope to get it wired in this weekend.
After new plug are in and you have tested the NE sensors, check that you do not have a plugged or non functioning injector.
 
#10 ·
Thanks for the advice. I put in some new plugs and it ran better. Long enough for the fuel pump to quit! A couple of blows with a hammer and it started pumping again. I guess the pump is on it's way out. I never did look to see how well the fuel flowed out of the petcock after cleaning the strainer. As weak as it was coming out I could see how the bike behaved like it was already out of fuel even though there was over a gallon still in the tank. Does anyone know how much gravity plays a part in the fuel system? Since the pump isn't in the tank it seems to be highly dependant on a strong flow past the filter.
Still haven't done the Suzuki sensor swap. Did my taxes instead. Not sure which task would have been more fun.
 
#12 ·
I checked the resistance of the speed sensors and got 151 / 153 ohms. Guessing that is good. There was quite a bit of rust on the little sliver of metal that I guess is the pick up. Guess that is bad.

When you have acces to the Ne-sensors and they are the original ones from 1982 always!!!! replace them for new ones (LX579) Saves you work again when they fail and they will!!
If there was a leak from the mechanical seal they get very hot and will crack sooner or later.

The Pb-sensor should also be replaced. These are also 36 years old and don`t give the right output anymore. Replace it with the Suz.

Good luck
 
#13 ·
Thank you Dutch, I will have to double check that. I never noticed the color of the tap on the petcock. I only drained the tank using the outer most fitting. The other hose was still connected. There wasn't any room to get a funnel under the tank. Isn't the return pipe inside the strainer only open at the top? Fuel can't flow out below a certain point?
 
#14 ·
The return pipe is only open at the top. Check if the strainer and return pipe is loose from the tap.
If the strainer and pipe are loose the return fuel is mixed directly with the fuel going to the pump and will create gas bubbles.
The benefit of the return pipe is to prevent irregular fuel current flows.
The possibility exist the fuel pump gets fuel mixed with gas bubbles so the pressure will go down.
 
#15 ·
Hope I have some simple fix for this. Ever since I pulled the fuel strainer out of the tank and cleaned it the pump has had an issue of not running. Sometimes it is at start up sometimes after the bike has been going down the road. The last couple have been while riding the bike. I tap on the pump with the largest allen wrench in the tool kit and the bike eventually starts. I noticed that my clock goes back to 1:00 am this last time, like the battery has been disconnected.

Still need to put in the Suzuki PB sensor and the bike is dying while I am coming to a stop. Then won't restart. May be 2 problems.

Any ideas?
 
#17 ·
One day I will have some good news to report. The new Denso pump fixed one problem. The bike starts every time now. I wired in the Suzuki sensor 2 days ago and put about 70 miles on the bike. The bike came to a rough idle initially. I does run better below 3500 rpms as long as you man the throttle. It does not want to idle. The plugs are still black. You can hear and feel the engine stumble at about anything under 2500 rpms. Yesterday at a stoplight I thought I noticed puffs of smoke blow past me each time the engine stumbled. Fuel mileage at yesterday's fill up worked out to 32 mpg. Can the fuel pressure regulator be adjusted manually or is it based strictly off manifold pressure/vacuum? Bike runs well over 4000 and pulls hard on boost.
 
#18 ·
Maybe you need to have the injectors cleaned? - They have very fine filters in them which could easily be clogged and not letting enough fuel to flow.. It's simple to take them out and have them serviced.
It could eliminate another problem. Can you dial the idle up a little bit ? What RPM is it idling at after the bike is warm??
 
#19 ·
I was wondering if an injector can get stuck open? That would explain the black spark plugs. Since I have had the bike I haven't trusted it to set the idle. It idles so poorly below 2000 I just don't risk it dying at every stop. The bike seemed to be a little more cold natured once on the move with the Suzuki sensor. I don't dismiss any problem at this point but if the injectors are plugged up then shouldn't the bike be leaned out instead of running so rich it is sooting the plugs?
 
#20 ·
Yes, injectors can get stuck in the open position or be so gunked that they stay open too long.
Until you have them cleaned and tested you will still have idle issues.
 
#21 ·
Ok, makes some sense. Just seems to me that if there is that much trash it would be plugged up before the trash got to the point that the injector gets stuck open. I have seen what ethanol can do to little filters on my SeaDoo carburetor's. Those filters are about the size of a pencil eraser and were packed solid.

The fresh oil in the bike turned black pretty fast and smells a bit like gas.

I contacted one of the shops recommend here for injector service. Hope to have them out and in the mail this weekend. Not looking forward to getting the mounting screws out.
 
#22 ·
I got word that my injectors have been cleaned. They won't be back until sometime next week. The results didn't show any obvious problems. I was worried when I noticed that only one cyl had the JIS screws still holding things together. Someone has removed the injectors before.

Before I sent the injectors off, I put 2 brand new plugs in and ran the bike. After 10 minutes the plugs were black. I did notice the occasional puff of smoke while I stood next to it each time it stuttered/stumbled.
 
#24 ·
Don't know if the problem has been solved? If so share your experience, maybe someone will benefit from.
I asume you have measured the fuel pressure and the compression? Also check the Ne-sensors. If one is broken the the ECU is going in fail safe and the engine consumes more petrol.
 
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