87 k75s CONSTANTLY (every ride) cleaning the injectors - HELP

[jimnto]

Two years ago I picked up this 87 that sat for 10 or 20 years. I replaced the fuel pump, cleaned the tank. replaced all submersible fuel lines in the tank to the rail, cleaned the injectors and got it stumbling along. After buying Mostplus ( https://www.amazon.com/MOSTPLUS-0250.../dp/B07PMVW9L8) injectors on AMAZON it fired up and ran like stink the remainder of that season and last.

This year I can't make it three blocks before it feels like it is running out of gas and if I don't turn around - it gets worse and worse until it hardly pulls my weight. Once home I have to pull the injectors. clean the injector filters in acetone and reassemble. It runs well until I hop on and drive three blocks.

Do you think maybe the return line from the rail and the pressure regulator should have been replaced too? Do you think skungey gunk is finally breaking loose and filtering back through the rail? It seems weird because gas should be going away from the rail and the new filter should not be letting skunge into the rail.
It always seems to be just one injector and it isn't flakes, usually just on injector screen is just dark - can't see light through them.

I need ideas men! Why do i get it clean and it clogs soon after?

[98lee]

Is the tank venting properly? Does popping the gas cap change anything?

Have you replaced the filter again? Or you can check it by removing it, draining it, and letting it dry out overnite. Blow LIGHTLY through it with your mouth. Any resistance more than blowing through a large diameter milkshake type straw suggests changing the filter.

Did you clean the well below the fuel pump pickup?

Reclean the fuel rail and tank. EVERYTHING needs to be clean! Removing, inspecting, cleaning and/or replacing the regulator and both it’s lines would be a good idea.

For a bike that has sat that long, ANYTHING that touches the fuel is suspect.


Let us know what you find.

[PoorUB]

This year I can't make it three blocks before it feels like it is running out of gas and if I don't turn around - it gets worse and worse until it hardly pulls my weight. Once home I have to pull the injectors. clean the injector filters in acetone and reassemble. It runs well until I hop on and drive three blocks.

Are the filters visibly dirt when you clean them?

I find it hard to believe the filters clog up solid in just a few minutes running time. My guess is you have some other issue that "cures" itself while you are tinkering with the injectors, just to pop up again in the three block ride.

[GTRider]

When you cleaned the tank were you able to remove all the black spooge that used to be the fuel pump isolator? That rubber socket turns into a black tar-like spooge when left soaking in old gas. That might be what you are seeing at the injectors.

On the last neglected k-bike I resurrected I had to use a steam cleaner to remove the spooge.

Best,
DeVern

[jimnto]

Are the filters visibly dirt when you clean them?

I find it hard to believe the filters clog up solid in just a few minutes running time. My guess is you have some other issue that "cures" itself while you are tinkering with the injectors, just to pop up again in the three block ride.

Nope - the injectors. Usually one can't see through it with a light. The other two are clean. Today will be the fourth time i have taken them out. I kept thinking it was the last time. Now, since it is always one that is noticeably dirty - i am going to try and figure out which one and if it is always the same one. The fuel rail looks clean but I am going to try some pipe cleaners. I also took out the regulator and flushed it with some acetone. It is hard to see down one little tube but I don't think it looked clean. What works against that theory is why would fuel back up from the regulator (if that is the source) and why only one injector.
O what fun it is.

[jimnto]

When you cleaned the tank were you able to remove all the black spooge that used to be the fuel pump isolator? That rubber socket turns into a black tar-like spooge when left soaking in old gas. That might be what you are seeing at the injectors.

On the last neglected k-bike I resurrected I had to use a steam cleaner to remove the spooge.

Best,
DeVern

True the fuel pump mounting plate was a ness and I didn't use a steam cleaner. Do you think the spooge is getting through the fuel pump and the fuel filter? I haven't taken out the fuel filter yet - but if it has to come out 0-it has to. Thanks for the reply

[GTRider]

True the fuel pump mounting plate was a ness and I didn't use a steam cleaner. Do you think the spooge is getting through the fuel pump and the fuel filter? I haven't taken out the fuel filter yet - but if it has to come out 0-it has to. Thanks for the reply

I had assumed you replaced the filter same time as pump. The black spooge really needs to be completely cleaned out of the tank, and that’s usually a tough job. One wouldn’t think it could get through a screen, pump, and filter but remember—it became spooge by dissolving in old gasoline so if any of it is left in the tank it’s possible.

Best,
DeVern

[parked2long]

You need to remove the pump and filter
Remove the tank and clean the inside of the tank until it is super duper clean
New hoses and filter, then reinstall I would put new hoses from the tank to the fuel rail too.

If you have the original injectors I would send them out to be cleaned and flow tested.

That's what I think