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Author Topic: Not Running - HELP Please. Suspect fuel issue?  (Read 1542 times)
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« on: August 15, 2019, 11:08:29 AM »

wondering if anyone can help me or give me any advice regarding my Honda CB-1
Was riding down the dual carriageway doing around 40, biked seemed to be running fine at this point, as I pulled out to over take it suddenly lost power. It continued on for about 200-300m sounding a little rough then cut out completely.

I was able to start it around an hour afterwards and attempted to move it closer to home, it again ran for a short distance sounding a bit suspect then cut out once more.
Have checked all the plugs/leads and they seem to be functioning properly. Just changed the plugs and fuel filter as a matter of course but wondering if there's something else obvious I should be looking for.

I have a suspicion it is a fueling problem/not getting enough fuel, i did notice whilst it was spinning over there was alot of fuel being passed out of what seemed to be the carb leak off/breather pipe.

I have taken the tank off, drained it and checked for any impurities in the tank, also tried firing it with a bit of easy start sprayed into the carbs but no luck.
The fuel pump seems to be 'knocking' on and off whilst turning over so that would suggest its operating as it should.
Not sure if there is any tests that can be carried out on the pump or the wiring system as a place to start?

Any advice appreciated!
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« Reply #1 on: August 16, 2019, 12:59:23 PM »

I think you're right that it sounds like a fuel problem, so I would check that fuel level is high enough that the petcock does not need to be on Reserve or that the nylon filter screen inside the tank is not clogged. Do those by pulling the fuel line off the petcock, adding a spare piece of fuel line into a container then opening the petcock to ON and Reserve watching for good flow. If flow is very slow, open the tank cap to eliminate the possibility of a clogged air vent.

There are also individual small filter screens attached to the float valve seats, so if the above tests check out try opening the float bowl drain screws 1 turn one at a time (with a catch can under each drain spigot) and watch for continuous flow. NOTE: The fuel pump is not needed if the tank level is 1/2 or higher, so this test can be done with the key off/full tank. If your fuel pump were to be bad and tank level was very low you would get fuel starvation. Of course you can test the pump by putting a spare hose and catch can on the pump outlet and cranking the engine.

The strange symptom is the fuel leakage out of the carb vents. I can't think why that would happen. Let us know what you fine, and good luck.

« Last Edit: August 16, 2019, 01:02:21 PM by Spurlock » Logged

1975 Honda CB125S2, 1989 Honda NX250, 1989 Honda GB500, 1989 Honda CB-1, 1997 Honda CB50V
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« Reply #2 on: August 17, 2019, 02:31:26 PM »

You'd have to elaborate in exactly where fuel is coming out. That'll be your problem for sure. Can only imagine a float has got stuck shut? More usually they would fail open though.

Typically if it runs only a short while it's often due to the vent getting blocked. Try again with the fuel cap open.

Edit: would fuel come out the vent if the filter screen in the carb were blocked?
« Last Edit: August 17, 2019, 02:34:21 PM by a_morti » Logged
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