On and off zoom

TheJimGuy · Oct 2, 2016

Having an intermittent problem that is now beyond my troubleshooting, please jump in.
3 y/o motor (Grubee 5), 3,000 miles. Strong performance.
Two weeks past I changed out the gas tank for a 2.5L.
This week I had several seconds of no power (no bang). I double checked the gas shut offs (one on tank, one on carburetor). Inline fuel filter (glass) full of fuel. Played with the tickler on the carburetor float. Bike started back up and had only one quick hiccup the rest of the way home (1/2 mile). Next day out, reoccurred, but for longer time. Got home and changed the carburetor, problem persisted. (Removed the bowl and verified it was full of fuel). Reinstalled original carb.
Next areas I was going to attack would be the magneto and CDI.

Suggestions?

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bairdco · Oct 3, 2016

Before you start messing with everything else, use common sense troubleshooting procedures.

If the bike ran fine before you installed the new tank, put the old tank back on and see if the problem goes away.

If it does, the problem is with the new tank.

Messing with multiple things like magnetos, carbs, etc, will just compound your problems.

Take things one at a time and eliminate them step by step.

My "guess" is the new tank isn't venting properly, or has some crap in it that's interfering with fuel flow.

Also, check your plug. Make sure it's not wet. Did you mix your fuel right when you went to the bigger tank?

Never overlook the simple things.

KCvale · Oct 3, 2016

Good advice baird, start with what was changed.

2door · Oct 3, 2016

Great advice! The fuel tanks come with dirt, rust scale and lots of other stuff that won't do your engine any good. And they don't even charge you for it.

If you're using the in-tank fuel strainer there's a good chance it is clogged, or partially clogged with debris from your new tank. There is a lot of good suggestions on the forum for dealing with a new fuel tank and their associated problems.

Tom

ZipTie · Oct 4, 2016

Besides the tank advice it could be a short where kill wires touched or cdi wires are not connected tight enough. When you put the new tank on you may of bumped wires causing a intermittent short. This is based on the fact you did say fuel was in the line. Also a big bubble burp from tank change may of happened causing your float bowl to be almost empty for a brief time. May never happen again hopefully.

TheJimGuy · Oct 5, 2016

Thank you for all the feedback. Here is where I stand at this moment:
CDI and kill wires zip tied to the front tube and not near the tank or fuel line, but rechecked anyway, all good. Thank you for that line of thinking.
Found the spark to still be present when motor cut off. Still leaning to fuel issue.
The tank did not come with a shutoff or filter.
Prior to installing, the tank was rinsed with gas to remove any debris from the manufacturing process. Shutoff installed and a bran new inline glass filter put in place.
Noted that my shut off valve did not fully shut off. Changed it out.

Now the "Ah Ha".
***** However, The inline filter was the problem. Assembled wrong from the factory. compared it to another bike that I have. Gasket holding the filter element in place was the wrong size. When secured at the factory, it expanded to touch the wall of the glass, effectively cutting off almost all the gas (pictures to follow). Put proper gasket in place, took on a 5 mile test run, all is right with the world. *****

KCvale · Oct 5, 2016

TheJimGuy said:
Thank you for all the feedback.
Put proper gasket in place, took on a 5 mile test run, all is right with the world. *****

Cool, glad we could help ;-}

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ZipTie · Oct 5, 2016

Thanks for following up and sharing your found and fixed fuel filter gremlin story.

bairdco · Oct 5, 2016

There ya go. Much better than changing cdi's, magnetos, and whatever else only to find out it was a simple problem after all.

2door · Oct 5, 2016

Thank you for the follow up report.
It's always appreciated when members let us know if the advice given helped them.

Glad you're back in the saddle.

Tom

KCvale · Oct 6, 2016

2door said:
Thank you for the follow up report.
It's always appreciated when members let us know if the advice given helped them.

Tom

Ditto.
I take an hour or two most every day to come in and help, it's nice to hear back with thanks for the help and it worked as that is we get for taking the time to help.

TheJimGuy · Oct 16, 2016

Attached (if I did this correctly) is a JPEG of the filter this the overly compressed white gasket, and another with the correctly sized/compressed black gasket. Simple fix, bugger to isolate.
Jim

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