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Fuel In Remote Vac Line

Old 04-25-2019, 06:58 PM
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Fuel In Remote Vac Line

Recently did the valve clearances and a few other minor jobs.

one was to replace the remote vacuuam lines that I use when syncing the carbs.

when I removed the front line it had some fuel in it.

what would cause this?

The carbs are seated correctly, the intake rubbers are all but new as well as the clamps, the Air filter is new, the TPS is set at 500, and the carbs are synced.

Could it be float height ? Needle and seat valve , emulsion tube ?

occasionally when I start it it backfires.

I think the two are linked

Any ideas ?

Last edited by kenmoore; 04-25-2019 at 07:05 PM.
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Old 04-26-2019, 05:59 AM
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Originally Posted by kenmoore View Post
Recently did the valve clearances and a few other minor jobs.

one was to replace the remote vacuuam lines that I use when syncing the carbs.

when I removed the front line it had some fuel in it.

what would cause this?

The carbs are seated correctly, the intake rubbers are all but new as well as the clamps, the Air filter is new, the TPS is set at 500, and the carbs are synced.

Could it be float height ? Needle and seat valve , emulsion tube ?

occasionally when I start it it backfires.

I think the two are linked

Any ideas ?
I may be misunderstanding the question or situation but...

The front vac line is not connected to anything when not in use for carb syncing ...so Im assuming you mean rear line?

And the rear line stock is feeding the fuel petcock vacuum, and commonly Y'ed off to a line for carb syncing...so if you have fuel in the rear vacuum line Id say it came from the fuel petcock.

If you mean the front vac line I have no idea how raw fuel could collect in that.
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Old 04-26-2019, 09:05 PM
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Originally Posted by E.Marquez View Post
I may be misunderstanding the question or situation but...

The front vac line is not connected to anything when not in use for carb syncing ...so Im assuming you mean rear line?

And the rear line stock is feeding the fuel petcock vacuum, and commonly Y'ed off to a line for carb syncing...so if you have fuel in the rear vacuum line Id say it came from the fuel petcock.

If you mean the front vac line I have no idea how raw fuel could collect in that.
Is it possible, if the front carb float valve is leaking, that fuel could running down into the boost joint screw?
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Old 04-27-2019, 04:12 AM
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Thanks for the replies.

The hose I am referring to comes of the base of the front cylinder and is independent to any of the vac lines for the petcock.

i replaced the bolt and fitted a nipple that the vac line attaches to in the vac port at the back of the front cylinder.

I am thinking that it is the needle and seat or too high a float level that is causing it.

The fuel does not appear to be making it into the sump as the oil level is consistent and does not smell strongly of fuel.

i thought that someone on here may have remote vac lines for syncing carbs ad experienced the same situation.
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