Thread: fuel line bleeding
04-02-2010, 01:18 PM #1
fuel line bleeding
i have done searched on how too and read up on it and what not, but im having a hell of a time.
there are three lines from the fuel sender.. one vent two fuel.. well one fuel line has gas and air bubbles and the other has nothing... and im 99% sure they are hooked up right... but i cant tell.. the air vent is all the way too the right next too the wires for the gas level... does this sound right?
04-02-2010, 01:36 PM #2
- Join Date
- Jul 2007
- near Toronto, Canada
The fuel tank nipples are marked. Small, but there are markings. Look closely around the fuel sender for markings.
The Vent nipple simply opens into the inside top of the tank.
The fuel Return nipple also is open at the top of the tank.
Only the Main fuel supply connection actually reaches down deep in the tank, to pick up fuel from the bottom of the tank.
If you blow air into the fuel supply fitting, you should hear the air bubbling up from the fuel intake at the bottom of the tank.
If you blow air into the fuel supply fitting and you don't hear the bubbles, then you may not have the correct fuel supply nipple.
95' Polaris 750sl Fuel Sending
04-02-2010, 01:51 PM #3
ok cool i will go and look now for the mrv.. i thought two lines where suppose too fill with gas from the tank.. but i am looking at a diagram now and the one thats empty is the line that comes from the center carb.. i assume this is the return line..
04-02-2010, 02:00 PM #4
i just went and checked.. weird my fuel sender has return main vent and reserve.. but only three nipples.... and the line that has vet has teh gas coming out of it.. and the other says main and return... im lost.. whats confusing me is i made sure i had them alll in the spots i took them off..
could the markings be wrong? and all the senders are the same but some where put on with three nipples and others with four
04-02-2010, 02:08 PM #5
- Join Date
- Jul 2007
- near Toronto, Canada
From the fuel tank fuel pickup at the bottom of the tank, it goes through the tank sender supply connection at the top of the tank.
Then the fuel gets sucked under negative pressure to the fuel pump, going through the fuel filter and shut off valve along the way.
From the fuel pump, the fuel goes under pressure into the carbs. The carbs dump the excess flow into the fuel return hose.
The fuel return hose then goes back to the tank, dumping the returned fuel back into the tank.
Note: There is a restriction (small hole) that the fuel must flow through to get from the carb into the return line. That restriction is what allows the fuel pump to develop fuel pressure inside the carbs.Since the fuel supply all the way from the tank pickup to the fuel pump is actually under suction, any air leaks will create bubbles inside the fuel. If you constantly see air bubbles inside the fuel supply hoses, then you have an air leak somewhere, and it needs to be fixed.
One the early Fuji engines, the actual restriction was a small metal slug with a tiny hole through it. That restrictor was inserted inside the fuel return hose, a couple of inches down from the carbs.
On later models, the restriction is located inside the carb return fitting, not inside the actual hose.
When properly sealed up, there should be very little air in the fuel supply hose, once the engine has had a chance to pump some fuel volume through.
Places where air leaks often occur include;
the fuel selector valve (it has an O-ring inside that can age and leak air),
the fuel/water separator,
poorly clamped hose ends,
and on the early model years, old and cracked fuel lines inside the fuel tank.
04-02-2010, 02:21 PM #6
ok well i think its hooked up fine.. i just got to run the air bubbles out of it... the "main" line is full of gas except for the air bubbles.. i can get it too start a bit with full choke, then it dies.. so im going too bring it over too the boat launch and get her running in the water on the trailer first...
04-02-2010, 04:41 PM #7
at one time polaris had four lines attached to the pickup.
vent,return,main,reserve.then polaris decided to to drop the reserve feature and had a warning on the mfd to alert you the tank was getting low.the main line went to within about 3 inches of the bottom the reserve goes to the bottom,so polaris dropped the main line and uses the reserve as the main feed.so we have the vent which connects to the check valves,return which returns fuel from the carbs on the domestics it attaches to the mag carb on twins and the center carb on triples.the res (reserve) is the feed line and connects to the shutoff or f/w seperator then to the tee on triple carbs or the pto carb on twins
04-02-2010, 04:46 PM #8
- Join Date
- Sep 2006
i used a primer bulb , this air in the fuel line issue shouldnt be that big of a problem its not a diesel i wonder why its giving you so much crap
04-02-2010, 07:31 PM #9
i tried too get it going at the ramp and couldn't get it started unless i dropped some gas down the carbs and it ran for a bit then shut off, then the battery died...
i am going to charge the battery and try it again tomorrow.. i triple checked the fuel routing.. and im positive its right..
04-02-2010, 07:33 PM #10
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