[RocksBlues]

my 83 vt750 hasn't been running quite right lately. The other day while working on it I noticed air in the inline fuel filter and when I rev the throttle air bubbles are being forced up to the carbs. The fuel filter always seems to be only about half full of fuel and the rest is air. I bypassed the petcock thinking it was sucking air and it didn't help. I have looked and can't find any fuel leaks so I am not sure how the air is getting in the lines. Any ideas?

 

[dgraves49]

It is possible that you have a crack in the fuel line between the tank and filter, especially if they are original. It wouldn't necessarily leak but could allow air in when the fuel pump is sucking. There could also be a hair line crack in the fuel filter letting air in. Neither are very expensive to replace.

 

[tobimaru]

Agreed, bypass the filter and use a new line, see if the bike runs any differently. If the plastic on the fuel filter is dark brown or tarnished looking it probably is time to replace it anyways. They're white when they are new.

 

[RocksBlues]

The filter was replaced before winter and most of the fuel line is new, the only old fuel line is between the reserve tank and where the petcock was. I'm going to replace that section today.

 

[cshaw07]

I replaced all of my fuel line minus a tiny piece... yep. it split open on me next ride. Lesson learned.

 

[gat803]

It's normal to see air in the filter/filter only half full.

 

[Eagle7840]

my 83 vt750 hasn't been running quite right lately. The other day while working on it I noticed air in the inline fuel filter and when I rev the throttle air bubbles are being forced up to the carbs. The fuel filter always seems to be only about half full of fuel and the rest is air. I bypassed the petcock thinking it was sucking air and it didn't help. I have looked and can't find any fuel leaks so I am not sure how the air is getting in the lines. Any ideas?

Normal for the fuel filter as you described. If your 750 has sat a bit over the winter months you may have some varnish or gumming in the carbs. Add some B12 per instructions on the can to clean that crud out when riding.