CX fuel problem
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Thread: CX fuel problem

  1. #1
    Tadpole
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    Default CX fuel problem

    I did post in the WTB section re. fuel pump for a CX 2400. However, thought I would post here to capture the brains trust further.
    Trying to get a 2400 Pallas ready for sale.
    Unfortunately there is no fuel being pulled up from the tank.
    Pretty sure its the fuel pump.
    Putting out feelers for anyone with a spare pump laying around.
    However I have also noted:

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    Did the fuel in the carb trick to begin with as it hadn't been run in quite awhile.
    Pump wouldn't prime. Filter was not filling. The line from the tank to the pump is dry.
    Put an extension onto this line so I could suck the fuel up. No luck and a head ache.
    Could be blocked down the tank end?
    When sucking on the line you can hear it bubbling.
    Forgot to mention the pump is delivering a pulse to the carby side line. Not sure how strong this should be though.
    Also the intake side hose seems to be cracked a little on the end, could it be sucking air. hmmmm.

    Any help is greatly appreciated.
    Wish to sell this car soonish.
    It is a an '82 Pallas 5 Speed which is in good nick.

  2. #2
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    My mate had a similar problem in his GS. Try running a line from a bottle of fuel straight into the fuel pump and then cranking, that way you will determine whether it's a problem with the lines or with the pump.

    Wishing you all the best in getting the CX going.
    79 cx2400 pallas c-matic

  3. #3
    1000+ Posts gerrypro's Avatar
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    Pull out the tank and drain it until it is clean. Then check the fuel pick up in the sender unit. It has a very fine screen and will clog easily if there is foreign matter in the fuel. ( Three hours waiting for a tow on the Eastern freeway is how I learned about this problem). Remove the pump and test its valves by the suck and blow method. Pressurise the inlet with the pump immersed in petrol and see whether there are bubbles coming from the shaft, if so the diaphragm is perforated and the unit will need replacing.
    Cheers Gerry

  4. #4
    Too many posts! JohnW's Avatar
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    I fitted an electric fuel pump on the inside RH mudguard (actually skp fitted that one). Wonderful as you use the pump not the starter motor to fill the carbie.

    Not arguing with any of Gerrypro's advice, I'd add - pipes and filters are critical too. But for a car used less than daily, an electric pump is cheap and effective.

    Good luck with the sale. CXs should be worth more than you'll get, but that is a separate discussion....

    Cheers
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  5. #5
    Tadpole
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    Thanks for the replies fellas,
    I fitted a siphon pump to the line running to the tank to see if I could draw fuel up. No luck.
    I have added around 10l of fresh fuel so the pick up must be submerged now.
    I reversed the pump and blew down to see if I can hear it bubbling in the tank.
    But there is more a loud hiss coming from the left hand side rear. Shes up against the garage tight so hard to get there.
    I assume its a hard line from engine bay to tank. But it sounds like a perforated hose hissing at the back.
    Any diagrams would help if available.
    gerrypro the car has a tow bar fitted so it will be a SOB to pull the tank out whilst grounded.
    I pulled the pump off but I think its ok. Pulling it off was difficult, reinstalling is impossible without a 13mm ratchet ring spanner it seems. Tomorrow to the tool shop at lunch time.
    Then i can get it up and put some jack stands underneath to find the source of the apparent hissing.

  6. #6
    1000+ Posts gerrypro's Avatar
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    Quote Originally Posted by PROJET_L View Post
    Thanks for the replies fellas,
    I fitted a siphon pump to the line running to the tank to see if I could draw fuel up. No luck.
    I have added around 10l of fresh fuel so the pick up must be submerged now.
    I reversed the pump and blew down to see if I can hear it bubbling in the tank.
    But there is more a loud hiss coming from the left hand side rear. Shes up against the garage tight so hard to get there.
    I assume its a hard line from engine bay to tank. But it sounds like a perforated hose hissing at the back.
    Any diagrams would help if available.
    gerrypro the car has a tow bar fitted so it will be a SOB to pull the tank out whilst grounded.
    I pulled the pump off but I think its ok. Pulling it off was difficult, reinstalling is impossible without a 13mm ratchet ring spanner it seems. Tomorrow to the tool shop at lunch time.
    Then i can get it up and put some jack stands underneath to find the source of the apparent hissing.
    One needs universally jointed wrists and elbows. You cannot clean the fuel pick up without removing the tank. What year is the car? Mine is 1978!
    PROJET_L likes this.
    Cheers Gerry

  7. #7
    Tadpole
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    My 2 cents:
    Simplest way to get it started to be able to move it, access tank etc (in my opinion) would be to run a fuel line from a jerry can to either the pump input (simplest, if you think the pump itself might be serviceable enough), or straight to the carb using a temporary electric pump. You could even just set up a siphon with the jerry can on the roof (obviously all normal safety considerations for working with fuel / electrics etc must apply!). Ideally you also run the return line to the jerry can, or block it off (if you just set up a siphon), but to run it long enough just to move it you would just be pumping excess to the tank if you leave the return line as it is.
    My 78 2400 Super (import) has an electric fuel pump somewhere down the back, both my 1980 2400s just have the mechanical pump (I think). Obviously you don't want an electric pump to suddenly activate with the outlet disconnected! And I would think that even if it's not pressurized it would be safest to block off the line from the tank while doing any of the above.
    I have a cheapy elec fuel pump I bought a while back from the eBay, and along with a few metres of fuel line it's helped start and move many a carbed vehicle, as well as draining stinky stale fuel. However I wouldn't install it as a permanent pump as last time I used it, it was starting to weep fuel from the pump body. So - might be time to bin that one :/
    Good luck with it
    PROJET_L likes this.

  8. #8
    Too many posts! JohnW's Avatar
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    This way you put fresh fuel in the carbie too. Good idea I reckon, done with due care of course....
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  9. #9
    Tadpole
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    OK investigation complete.
    Did the Jerry can into the pump with a little fuel in the carb.
    Once I had reinstalled the pump that is. What a SOB of job. I came to the realisation that the CX engine
    bay is designed on a principle that mimics a teenagers bedroom. Sh*t everywhere.
    Ran well, seeing not started properly for a few years.
    She jumped up straight away. Set it to high and placed axle stands under the two points at the rear.
    So pump is good. It must be the hissing sound I get when pumping air back to the tank.
    Got the missus to do the siphon pump to try to locate the sound. Must be the hose that joins the line
    to the tank. Am I correct in assuming there is a rubber line as a vibration isolation between the tank and
    the hard line that runs the length of the car?
    Am I also correct that rectification will require dropping the tank?

  10. #10
    1000+ Posts gerrypro's Avatar
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    Yes! Rubber fuel hose from sender to plastic line. Yes! You will have to drop the tank.
    Cheers Gerry

  11. #11
    Tadpole
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    Thanks GerryI thought you would say that.Drain point is at the front of the tank?How are the straps released?

  12. #12
    Tadpole
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    All done,
    rubber hose to the tank had the consistency of putty.
    Car is running now, however the fans don't seem to want to play.
    Turned it off before it got hot.
    Next thing to sort urggggg.
    CXVingtCinq and JohnW like this.

  13. #13
    Fellow Frogger
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    A common no fan culprit will be the little button sensor on a bracket behind the radiator. If you short the terminals and the fans run, it may be dodgy. If you switch the A/C on, the fans should run at high speed, which will tell you the relays (most likely near the battery dog's breakfast) are working.

  14. #14
    Too many posts! JohnW's Avatar
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    They have a curious system, running fans in series for low speed and in parallel for high speed, with a wee bunch of relays here and there around the battery and under the LH headlamp. I've replaced both the button sensor that works off air temperature AND the one that screws into the radiator. All works well, at present.....
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  15. #15
    Real cars have hydraulics DoubleChevron's Avatar
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    Before you go to all of this effort. There is a fuel filter hidden down infront of the petrol tank. You will need stands to get safely under there. Change this before going any further.

    seeya,
    shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/citro%EBn-forum/90325-best-project-car-you-have-ever-seen.html
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  16. #16
    Tadpole
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    Quote Originally Posted by DoubleChevron View Post
    Before you go to all of this effort. There is a fuel filter hidden down infront of the petrol tank. You will need stands to get safely under there. Change this before going any further.

    seeya,
    shane L.
    Hi Shane,
    already done this. No filter between hard line and tank.

  17. #17
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by PROJET_L View Post
    Hi Shane,
    already done this. No filter between hard line and tank.
    Has it been removed? There should be one hidden behind a shield. It is a standard plastic crappy type filter that is probably 40years old! It is underneath the car, just in front of the fuel tank.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  18. #18
    1000+ Posts gerrypro's Avatar
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    Quote Originally Posted by DoubleChevron View Post
    Has it been removed? There should be one hidden behind a shield. It is a standard plastic crappy type filter that is probably 40years old! It is underneath the car, just in front of the fuel tank.
    Probably removed Shane! Mine does not have one at this position! If there is a bad load of fuel the gauze on the pick up is so fine that it will block long before the muck even gets to the in line filter.
    Cheers Gerry

  19. #19
    Tadpole
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    Well all seems to be going well.... I said to myself last night, time to move her out and give it a wash. Has been in dry storage for 8 years.
    Starts on the button and runs for approx 20sec and dies. F*ck it I said, time for a red.
    Tonight I went back to her and she does start and run on full choke, revs rise to 1500 and then dies.
    First two attempts she back fired on me too.
    Help!
    Carb issue maybe?

  20. #20
    Fellow Frogger
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    Carby is likely. Is the idle solenoid connected? It's a single spade connector at the back of the carby. It won't idle without it working.

  21. #21
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by David S View Post
    Carby is likely. Is the idle solenoid connected? It's a single spade connector at the back of the carby. It won't idle without it working.
    I have never seen an idle cuttoff solenoid that works. Most have had the idle adjusted so it idle poorly at higher revs and runs on when you switch it off. The fix is to pull the plunger out of the solenoid. That doesn't fix the running on though

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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