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Help Suzuki Across Fuel Line Air Lock

Discussion in 'Suzuki 250cc In-line 4's' started by Jethalter, Feb 17, 2019.

  1. Jethalter

    Jethalter Active Member Premium Member

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    Hey Guys,

    I've got a problem thats driving me nuts. If i leave the across sitting for say 3 days untouched (fuel tap off or on doesn't matter), when i go to start the bike it won't fire at all because of no fuel.
    You hear the pump prime for a say 2 or 3 pumps then it stops, but still no fuel in the carbies.

    The only reason i know its an air lock is i used to have an inline filter after the pump going to the carbs and i could see it empty and the pump wouldn't prime anymore.

    Anyway i found today that after a few turns of prime pump, key off wait 2-3 mins, then repeat. After about 10 mins i managed to just have enough fuel in the bowls to start. Once started and i could rev it, it cleared up and the bike is fine.

    I've tried 3 different fuel pumps, the carbies have been cleaned and have got new pilot jets and clear main jets, the diaphragms are good as well as the sliders.
    I haven't changed the needles and seats yet.

    Any ideas ????
     
  2. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    do you have a spare fuel pump relay ? the bigger question is why are your bowls emptying ? can post a pic of your float needles
     
  3. Jethalter

    Jethalter Active Member Premium Member

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    I do have a spare relay i can try that but the relay never seemed to be an issue or cause of concern.
    I dont have pics of the needles, i'd have to tear into the across to get some at which point i think i'd just replace the needles.
    But im thinking this is the only other main thing left that could cause it ??
     
  4. Cbuzz

    Cbuzz Well-Known Member Dirty Wheel Club

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    Your bowls are not empty. 2 or 3 pumps is not enough to fill both bowls.

    Your bowls are already full if it's only doing a couple of pumps. If your bowls are really empty the pump pumps for 10-15 secs non stop before it auto cuts out.
     
  5. Jethalter

    Jethalter Active Member Premium Member

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    Its taking a lot more prime cycles to get it to the point of starting, i have to turn the key on, prime gets about 3 clicks and stops, wait say about 2-3 mins for the air pressure in the line to go down, repeat this cycle about 5 times. then once it has done about 15-20 prime ticks on the pump. it usually has enough in the bowls to just start, then once started you hear the pump tick like crazy and then go to say 1 tick every 10 secs or so.

    Again the only reason i know its an air lock, is when i had the inline filter just before the carbs, i can see with the couple of initial prime ticks, that the filter was still empty.

    Am i getting something weird like the full bowls are evaporating the fuel over a couple of days(via the vent tube) and that possibly the needle and seats are sticking with the floats uptop ???
     
    Last edited: Feb 18, 2019
  6. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Two problems here.
    1 fuel not in bowls, where is it going?
    Are there any leaks around the bowl drain screws? Are the seals good? Is the engine cylinders full of fuel?
    2 pump not running long enough to fill bowls.
    Does the bike have a fuel pump cutout (as in pump will only run for two seconds without engine running or if bike fallen over) that may be causing pump to stop. Is pump getting full 12 volts? Any restriction in fuel flow?
    Suggest that you run a tempory wire from battery through a push button switch to fuel pump to make pump work to prime carbs. This will get you going, but you need to find out why fuel bowls empty.
     
  7. Jethalter

    Jethalter Active Member Premium Member

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    Fuel in the bowls over a couple of days in guessing is evaporating via the vent tubes.
    There is no leaks from the bowl gaskets or the drain tubes.
    No indication of the engine being flooded with fuel. When its hard to start the engine cranks fine and doesn't have a hint of firing.

    The pump doesn't run long enough to fill the bowls with fuel, the auto cut off in the pump stops it (resistance from the air lock in the lines).

    I have checked voltages at both the pump and relay (with bike off) at a healthy 12.5v. Also have tried powering the pump of a separate 12v battery to no effect. The auto cut off in the pump stops it.

    I've also changed the line from the pump to carbies just in case it had a blockage. No difference.
     
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Use some hoses and containers and connect the inlet of the fuel pump to an open container of fuel and the outlet to an open container. Then go through that starting sequence again. Note how much fuel it pumps before switching off.

    If it works then do the same thing again but this time connect the inlet of the pump to the fuel tank. Again, note how much fuel it pumps before switching off.

    Let us know what happens.
     
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  9. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Don't know where you are located but here in Tamworth it has been over 35c most days for the last three months and I can leave my bikes for a month in a tin shed and still have enough fuel in carbs to start them. Do your bowl vents have any sort of filter on them?
     
  10. Cbuzz

    Cbuzz Well-Known Member Dirty Wheel Club

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    Not sure where you are getting "Air lock" word from, do you mean air pocket ?

    With the GSX250F the pump automatically cuts out at a certain pressure. If you pull the fuel line off & direct it into a container it will pump for 10-15secs & automatically cut out. There is no cut out switch as such. It's pressure related inside the actual pump. There is only two wires going to the pump, positive & negative.

    2-3 pumps indicates your bowls are already full. The pump or fuel line itself may have a blockage but I doubt it as you said you've already changed it a few times. Could be the line ? Pull the line gonig to the carby & pump it into a container. Check it's flowing freely.

    I've got at least 10 GSX250F pumps here here & this is how they behave.
     
  11. Jethalter

    Jethalter Active Member Premium Member

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    Maelstrom - Its gonna be a few days at least before i can do so, when i get the chance i will let you know.

    Murdo - I'm just thinking outside the box here, i'm not sure whats exactly causing it but can only go from what i've seen so far.

    Cbuzz - The only reason i'm saying Air Lock / Air pocket in the line is due to when i used to run a filter in line from the pump to the carbs (i don't no more), that after a few days when i went to start the bike that filter was bone dry of fuel, the pump would prime and then stop, and the filter was still empty of fuel (its clear see through).

    So example i had it running yesterday and went for a good ride. Today i started it up no worries. But if i leave it say from now till Sat, when Sat comes around its a major pita to start, to the point you will crank and it wont fire but crank it enough times that the battery will start to go flat. (I have a charge plug on the bike so i make sure its properly charged also).
     
  12. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Making assumptions when troubleshooting a problem is the best way to get grey hairs.

    Start with basics... what fuel are you using? If it's E10 then burn it up and replace it with regular 91.

    Check the fuel cap... is the breather working? A rush of air as you open the cap indicates that it may not be working.

    How do the spark plugs look?
     
  13. Jethalter

    Jethalter Active Member Premium Member

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    Probably explains why i have a shaved head then.

    Fuel is 91, no E10 or such.

    Checked the fuel cap, when you open it no rush of air or anything.

    Plugs not sure at the moment, I'm hoping to do a service on it this weekend including plugs, oil and filter. So see if that resolves any issues.
     
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  14. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    I would suggest draining the bowls when the fuel pump cuts out early to see if they are full or empty.
     
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  15. Jethalter

    Jethalter Active Member Premium Member

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    Will do that with the service on the weekend
     
  16. Andych

    Andych Well-Known Member Premium Member

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    I am trying to remember but does the Across have the high and low strainer on the petcock? Maybe try switching the petcock to reserve rather than run and see what happens..
    Could also be an issue with the petcock...
    I had a similar issue with my fuel pump when I had the Across and it was a dud fuel pump.. bought one from @kiffsta and it fired straight up..
    If your bowls are draining in that short period of time.. it isnt evaporation.. it is a leak of some sort.. its just a matter of finding it..
     
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  17. Jethalter

    Jethalter Active Member Premium Member

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    Def no fuel leaks of any kind, Could be possible dud pump, but i've got 3 across pumps and all do the same thing. I'm tempted to get a xvs650 pump asi know they are solid as.
    but im thinking its possible my problem lies elsewhere
     
  18. Jethalter

    Jethalter Active Member Premium Member

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    So i think i sourced the issue. Weak spark caused by a iffy battery.
    I tried to start it today without being started for 3-4 days, started then died, wouldn't start no matter how much cranking after that, took the seat off, plugged in my charge on the charge plug, and bam crank later after one minute on charge and it runs.
     
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  19. Andych

    Andych Well-Known Member Premium Member

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    Does it have the correct battery? The Across needs a battery with plenty of grunt. Don’t use anything smaller than is specified as you will have issues.
    Check to see if it is charging properly while running too.
    Plenty of bikes that age have reg/rec issues including burned or compromised wiring connectors, earth connections etc.


    Sent from my iPhone using Tapatalk Pro
     
  20. Jethalter

    Jethalter Active Member Premium Member

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    its going to be the next thing im going into, atm i'm just checking over front sprocket and doing the service, once thats done i gotta finish the twin disc front on it.

    edit : the battery is a motobatt MBTZ10S 8.6AH, a quick check on the multimeter with min v selected showed 11.6v cranking. if i get the chance later today i'll do the stator/rec reg tests.
     
    Last edited: Feb 23, 2019

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