bigfitz52--frustration in GA. Petcock and fuel mystery!

85 xj700n Maxim--did the basic rebuild of the petcock and followed bigfitz52's instructions. It poured gas. Pulled apart and did it again and it seemed to work. Installed clear fuel line and 90 degree filter from Chacal. After running the bike about 10 miles I checked everything and noticed no gas in the fuel line on the carb side of the filter. took the bike out again and it seemed to be starving for gas. Took off the petcock and filter and both seem to be clear with no restrictions. In fact, the petcock again seems to be supplying gas in any position when the engine is off. Manually filled the fuel line and filter and rode it again--about 5 miles. Fuel line empty again.

What's happening to the gas in the fuel line and where is the air coming from and why isn't the fuel line staying full of gas?? I'm stumped. Also, what should I look for that might be causing the petcock problem?

 

You specify that the fuel line between the filter and carb is empty--does that mean you can see fuel between the tank and the filter?

 

Couple questions:

is the fuel filter on backwards?

open up the oil plug and see if you smell gas?

is the fuel line kinked or too long?

does the petcock seem to be working on prime?

 

I can see the fuel line from the tank petcock to the filter and also from the filter to the carb inlet. the fuel line is new, the clamps are tight, and I manually filled the fuel line. Don't know where the air is coming from.

 

Fuel filter is on correctly--according the flow arrow on it.

No gas in the oil, and no overflow from the overflow tubes.

No kink in the fuel line, but it is a little long on purpose.

Darn petcock pours gas in any position--that's another rebuild problem I've had.

 

What I'm trying to get at--if there is fuel from tank to filter but only air after the filter, I would suspect the filter.

 

The filter seems fine, I removed it and blew throught it very easily. Sitting the line from the tank to the filter fills, but not from the filter to the carb. Running, both lines are empty, although I can see gas running down the inside.

 

Vacuum problem? It's vacuum operated, are you getting vacuum? Otherwise you'll just be emptying it and then no more will flow. It would have worked before because it was just leaking without vacuum, now it works properly and gas won't flow without vacuum.

One theory from a novice, anyways.

 

How's your vaccuum line?

 

Fix the petcock problem first! Apparently the rebuild kits suck big time and need some tweaking. I haven't had to rebuild any so I can't help you there.
I do not use a gas line filter because it restricts my gas flow to much. And no I do NOT have any vacuum or petcock issues. I just installed a NOS one. If the filter on the petcock is good and has no holes in it there is no need for the inline filter.

 

just thinking some more... pull your fuel line off your carb rail, set the petcock to prime, and see if you are getting good fuel flow

 

I will pull the petcock again tonight, re-clean and police everything, and re-install. I'll check for fuel flow from the petcock nipple, then attach the filter and check again and post the results. In reading bitfitz52's instructions again I noticed that he mentioned a check valve in the vacuum nipple which I will recheck, although I don't see how that would put air in the fuel line. This bike is fast becoming a hobby rather than a ride. Glad I have my Honda.

 

Once you get this "restoration" business out of the way, you'll enjoy it! Or like me, the wrenching is most of the fun!

 

Sometimes you have to be stupid to become smart. Removed tank to remove petcock and decided to go ahead and sync the carbs. Hooked up aux tank and the air was gone. Then it dawned on me, my tank was almost empty and I guess air was being pulled in through the main stack since I was operating on reserve or primary.

Removed the petcock, bought a polishing bit for my Dremel, and some wet sand paper. Took it completely apart and polished the seat, all inside surfaces I could get to, wet sanded all flat surfaces to a high gloss, and even removed and cleaned the vacuum check valve disk. Put a light coat of silicone grease on all flat surfaces and put it all back together. Works perfectly. Moral of the story: follow bigfitz52's instructions to the letter if you want to be sure it works the first time.

 

:lol: :lol: :lol: :lol: :lol: :lol: :lol:

 

For those inclined to to rebuild a Vacuum Petcock; the process cannot be more comprehensively detailed than BigFitz's How-to.

But, even the greatest "Do-it-yourself" illustrated presentation, meticulously followed step-by-step, won't result in success if the aftermarket parts don't fit.

Despite how carefully you attend to the details of rebuilding a Petcock; if it leaks when you get done you're out for the time and cost of the kit.

Your labor ( 2.0 Hrs X $25 = $50 )
50-Bucks + Kit ( Kit $34.00 ) ...

$85.00 in Virtual expense. vs. $79.95 ~ $95.00 NEW Part.

It's so much easier to open a box, install your New Petcock and save getting disappointed by rebuilding a Petcock and getting burned by parts that might not fit.

 

...unless the closest petcock available doesn't quite fit. My daily driver 750 Seca has the replacement that Chacal recommends as the best fit available. The location of the fuel outlet requires a sharper bend in the fuel line than I really like. The routing of the one on my parts bike is much better--I will likely use that one on the 'good' bike even if I need to rebuild it first.

 

Go ahead and rebuild it.
Have fun.
And, ... Good luck; too.

I just want the membership to know that rebuilding a Petcock with an aftermarket Kit; does NOT always culminate in success.

It's a crapshoot.