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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: EspressoForyoU on November 11, 2018, 07:50:47 PM
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I rode my new to me 1987 k75s today for around 50 miles. It ran great except for two instances. While rolling to a stop just above idle the engine “hiccuped” for about 1/2 a second. I guess stumbled might be a better description. Then about 20 minutes later at 1/2 throttle it stumbled again for a 1/2 second.
The PO said he replaced the fuel pump, fuel filter and injectors.
Any idea what could be causing two split second stumbles over a 50 mile ride?
At the end of the ride I added some “Heat” brand water dissipater to the tank but did not ride but a couple miles after that.
Thanks for your help.
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I rode my new to me 1987 k75s today for around 50 miles. It ran great except for two instances. While rolling to a stop just above idle the engine “hiccuped” for about 1/2 a second the engine stumbled. Then about 20 minutes later at 1/2 throttle it stumbled again for a 1/2 second.
The PO said he replaced the fuel pump, fuel filter and injectors.
Any idea what could be causing two split second stumbles over a 50 mile ride?
At the end of the ride I added some “Heat” brand water di
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greetings...
need more miles... back to back to back tanks of no corn ethyl and techron... lotts of techron...
j o
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I tend to think that random intermittent problems are electrical and on a bike as complicated as a brick usually are in a connection. A connection can be in a connector or a switch, any place where two parts touch each other to let electrical current through.
The worst thing about intermittent stuff is that you never really know if you fixed the problem. All you can do is check and correct all the things that might cause your problem and hope for the best.
I would start by cleaning and making sure the four pin tank connector is tight and making good connection. You could try to test it by wiggling it when the engine is running. That connector is famous for causing problems, especially on bikes that show signs of neglect or have been kept outside for long periods.
Beyond that, you need to go through every connection on the bike cleaning and making sure it's tight.
If the problem persists, it is possible you have an electronic component that is beginning to fail. Normally, electronics that have not completely failed will start to give problems when they get hot, and stop acting up when they cool down. The best example of this is the Hall Effect Sensors on the front of the engine that trigger the ignition. The best way to check that type of problem is to warm up the bike with a ride, and when the problem appears use a freeze spray on the suspect part to see if the problem then goes away.
I doubt your problem is a failing part, those usually result in a shut down that lasts a ot longer than what you are seeing.
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Agree 100% with Gryph.
A can of DeOxIt and some time cleaning the fuel pump tank, ECU connector and any others will go a long way towards solving or diagnosing your problem(s).
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Is there any debris in the fuel tank? Have you verified that the fuel pump connections with in the tank are tight, the hose connections within the tank are tight and the hoses themselves are in good shape?
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I'd suggest some electrical contact cleaner and then dielectric grease on electrical connections:
Hall sensors, jet-tronic, fuel tank, coils, plug-in relays in the relay box.....
Cleaner obviously to clean oxidation, then the grease to keep out moisture and air that causes oxidation.
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Pour water in the gas tank and hold it upside down for a couple minutes.
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Ride it until it stops doing whatever you don't want it to do. That works for me every time (so far).