Been a while since I updated this thread. Have had a power issue with the '85 LTD and took it off the road and into the garage in early July. Thankfully I have my 1800 to ride as well.
One of the troubleshooting issues is that there are no error codes on the ECU that makes identification of the issue that much more difficult. I do prefer fuel injection over carbs, but this is befuddling me.
I replaced the fuel pump and injectors as I mentioned earlier and possibly in another thread. The fuel pump was an Airtex E8312 - an in tank pump. When I started to have power issues again, I thought this might be the problem. I replaced it with a Spectra SP1186 - external fuel pump. This did not fix the problem, but the banjo bolt fitting is better for the application.
I have checked the fuel pressure in the system, 38 PSI with key on, 36 PSI with the engine at idle. Tested the fuel pressure up to 4000 RPM - steady at 36 PSI. No issues with the fuel delivery or the fuel pressure regulator.
I went back to Ontario in July and took the PB (MAP sensors), Gr/Gl (camshaft sensor for injector timing), and TPS off the bike I have there. When I got back, I replaced each sensor one at a time to determine the issue, but again no joy. The only sensor I left in place was the TPS.
I did not do the Ns (crankshaft sensor for engine timing) because I would have to take the front off the bike. I did do the continuity and resistance checks and found this sensor to be out of spec. I replaced it with a new PG sensor harness for an '85 ASPY/Interstate. The engine blocks are the same so I was able to install the sensors over/under the crankshaft wheel. The mounting arrangement is such that the air gap is predetermined and within spec. Here is the PG sensors installed:
I will only be using one of the sensors as the Ns sensor, and have the other as a spare so that if I need it I can just change the connector under the shelter and will not have to take off the front of the bike. Having done this, I have not fixed the issue.
I found a thread over on the CX500-650 forum about the PB sensor. Here is the thread:https://cx500forum.com/forum/cx500-cx650-turbo-forum/17499-pb-sensor-replacement-11.html.
The information is excellent and pertinent to what I am experiencing. The Reader's Digest version is that the PB sensor affects the operation of the engine up to 3000 RPM. After which it is no longer in play. I tested this and found that up to 3000 RPM, there is an increase in manifold vacuum of 10 to 12 inches. After 3000 RPM there is no increase in manifold vacuum so the PB sensors are maxed out and as I mentioned, no longer in play.
The fellows over on the CX forum have sourced a replacement MAP sensor and it is a:
Brand: Denso.
Type number: 100798-5630. Suzuki orderingnumber: 15620-35F00.
Suzuki description: Sensor Boost, IAP (Inlet Air Pressure) sensor.
They have found it to be an almost exact replacement sensor and many have installed this sensor to rectify the issue that I am experiencing. When I read this I sourced two and purchased them. One of the fellows took a faulty OEM PB sensor apart and found the internal connections to be less than stellar and problematic. It was also mentioned that the difference in technology between the modern MAP sensor and older ones is significant.
Here are some pictures of the sensor and my mods to the connector(s):
Since I have tried, within reason, everything else, I am going to install the Suzuki MAP sensors tomorrow and hopefully will see a significant improvement such that the issue I am having is fixed.
A lot of issues in play with a fuel injected bike. Learning a lot and will be able to update one of my other threads with a synopsis of what I now know about the '85 LTD Fuel injection system.
More to follow - good news I hope.
One of the troubleshooting issues is that there are no error codes on the ECU that makes identification of the issue that much more difficult. I do prefer fuel injection over carbs, but this is befuddling me.
I replaced the fuel pump and injectors as I mentioned earlier and possibly in another thread. The fuel pump was an Airtex E8312 - an in tank pump. When I started to have power issues again, I thought this might be the problem. I replaced it with a Spectra SP1186 - external fuel pump. This did not fix the problem, but the banjo bolt fitting is better for the application.
I have checked the fuel pressure in the system, 38 PSI with key on, 36 PSI with the engine at idle. Tested the fuel pressure up to 4000 RPM - steady at 36 PSI. No issues with the fuel delivery or the fuel pressure regulator.
I went back to Ontario in July and took the PB (MAP sensors), Gr/Gl (camshaft sensor for injector timing), and TPS off the bike I have there. When I got back, I replaced each sensor one at a time to determine the issue, but again no joy. The only sensor I left in place was the TPS.
I did not do the Ns (crankshaft sensor for engine timing) because I would have to take the front off the bike. I did do the continuity and resistance checks and found this sensor to be out of spec. I replaced it with a new PG sensor harness for an '85 ASPY/Interstate. The engine blocks are the same so I was able to install the sensors over/under the crankshaft wheel. The mounting arrangement is such that the air gap is predetermined and within spec. Here is the PG sensors installed:
I will only be using one of the sensors as the Ns sensor, and have the other as a spare so that if I need it I can just change the connector under the shelter and will not have to take off the front of the bike. Having done this, I have not fixed the issue.
I found a thread over on the CX500-650 forum about the PB sensor. Here is the thread:https://cx500forum.com/forum/cx500-cx650-turbo-forum/17499-pb-sensor-replacement-11.html.
The information is excellent and pertinent to what I am experiencing. The Reader's Digest version is that the PB sensor affects the operation of the engine up to 3000 RPM. After which it is no longer in play. I tested this and found that up to 3000 RPM, there is an increase in manifold vacuum of 10 to 12 inches. After 3000 RPM there is no increase in manifold vacuum so the PB sensors are maxed out and as I mentioned, no longer in play.
The fellows over on the CX forum have sourced a replacement MAP sensor and it is a:
Brand: Denso.
Type number: 100798-5630. Suzuki orderingnumber: 15620-35F00.
Suzuki description: Sensor Boost, IAP (Inlet Air Pressure) sensor.
They have found it to be an almost exact replacement sensor and many have installed this sensor to rectify the issue that I am experiencing. When I read this I sourced two and purchased them. One of the fellows took a faulty OEM PB sensor apart and found the internal connections to be less than stellar and problematic. It was also mentioned that the difference in technology between the modern MAP sensor and older ones is significant.
Here are some pictures of the sensor and my mods to the connector(s):
Since I have tried, within reason, everything else, I am going to install the Suzuki MAP sensors tomorrow and hopefully will see a significant improvement such that the issue I am having is fixed.
A lot of issues in play with a fuel injected bike. Learning a lot and will be able to update one of my other threads with a synopsis of what I now know about the '85 LTD Fuel injection system.
More to follow - good news I hope.