question about fuel filters

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  • #233660
    Marc Lipsius
    Participant

    @mrlmd

    My car now has 2 filters, one in the line before the fuel pump to catch any
    crap that might be in the tank, and one in the line to the carb after
    the fuel pump. I originally had a metal can fuel filter in the line before the fuel
    pump, but I put another one of those see-through plastic ones in the line from
    fuel pump to carb because I kept getting tiny bits of either rubber or
    plastic into my carb that would plug up the jet and starve my engine for
    fuel and cause it to stall while driving on the road. I put the second filter in so that I might see if any more debris gets caught before it enters the carb..  Even though the lines were new when the engine was rebuilt, I replaced them again, and the
    fuel pump is new and the carb was thoroughly cleaned before putting it
    on the car. I haven’t seen any more bits of debris in the filters, yet,
    and I have no other ideas where it came from. 
    For those of you with one or more inline fuel filters, I have a question about those see-through plastic ones (or any of then actually, just that you can see into the plastic ones, not the metal ones). Do they typically run with an air space in them or do they usually run totally full of fuel? My VW with the inline filters seems to run OK,  but looking at the filters, each is only maybe 1/4 or less full of fuel. Fuel gets through them, even in the upright position, and seems to supply the engine OK, but it looks strange, like they should be totally full of fuel, or at least with less of an air space inside. Has anyone looked at theirs to see if this is the way it is, or should I bother to try and get the air out of the line? And I have no idea how to do that aside from running the engine and pumping it through, which should blow out the air anyway.

    #246226
    Paul Mossberg
    Keymaster

    @pmossberg

    I have a clear plastic one, and there is always air in it.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #246227
    Dennis Brock
    Participant

    @dbrock

    Mine too.  I worried about it when I first got the car, but it never caused a problem.

    #246228
    Paul Allain
    Participant

    @pga64

    I also have a clear plastic filter and it always had air in it. I also gets a white substance that settles at the bottom of the filter. The last time I change the filter, I cut open the old one and found that the white substance was soft and putty like but not sticky. I don’t know if this is a coating from inside the gas tank starting to break up? Anyone have any idea of what this substance could be. It seems to passes through the fuel pump without any problem. I just have a filter on the outgoing side of the fuel pump.

    #246229
    Marc Lipsius
    Participant

    @mrlmd

    Anybody know what temp range those plastic filters can take before they melt?

    #246230
    Bill Gould
    Participant

    @texag71

    Geez. Now you guys have given me yet another thing to worry about and obsess over.

    1981 Lafer TI
    1600 cc Type 1 engine

    #246231
    Montie Henderson
    Participant

    @montie

    I had 2 filters on mine.  One in the back close to the tank.  Second one was a clear glass one (you know the ones with the replaceable filter inside, chrome fancy etc) between the fuel pump and the carb.  This one would only last about a month and then start leaking.  According to the mechanic at work, it’s not advisable to have a fuel filter on the high pressure side of the fuel pump.  Now I have relocated the second one just before the fuel pump.   

    #246232
    Dan Rosa
    Participant

    @dan-r

     I to had fuel filter trouble but none after i put a larger in line filter ,clear plastic type , from  walmart  the inside of my tank was oxidising being aluminum and sitting for 20 years i had to reseal it no more trouble but i kept both filters … Dan

    #246233
    Marc Lipsius
    Participant

    @mrlmd

    The ” high pressure” side of the stock VW fuel pump is only about 3-5lbs at max, and with good tight connections, with even spring type hose clamps, shouldn’t be any problem for leaks. I am more concerned with heat in the engine compartment and how much heat those plastic ones can tolerate. l had a metal can type filter in the line but I replaced it as I prefer the see through ones so I can monitor what’s going on in there.

    #246234
    Paul Mossberg
    Keymaster

    @pmossberg

    I know some friends that swear against the plastic VW gas filter. But it has worked for decades on stock VW, which probably have higher engine compartment temperatures than our replicas.

    So, while I don’t have a melting point for you, I continue to trust them in my own TD.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #246235
    Tom Colello
    Participant

    @gunfighter

    The plastic filters are fine in the engine compartment from a heat stand point. Just make sure they aren’t touching anything that might get hot. The necessity for two filters suggests to me that you may have a dirty tank or fuel line problem. One filter should be plenty and yes they never fill up completely.

    There is a lot of talk amoung the VW community about having a fuel filter inside the engine compartment to begin with because of a fire issue which is all to common. Just make sure your connections are tight and that the filter isn’t touching anything hot and you should be good to go. My filter, a metal one, is mounted in a bracket on the upper portion of the fan shroud.

    #246236
    edward ericson
    Participant

    @edsnova

    I had my plastic one between the fuel pump and the carb and it was no trouble, but after reading a lot of scare stories I replaced the rubber lines and moved the filter to the front of the engine (“back” of the fan shroud when you’re looking at it from the back of the car) to get it away from sparks and stuff. Seems to work fine either way.

    Also, always had air in it and at first that worried me. But works fine. Same thing with the same filter on the outboard motor.

    edsnova40793.5398263889

    #246237
    Richard Wobby
    Participant

    @richard-wobby

    you all interested me on this one…

    So two brown bottles and and old filter, I mean why throw them away, I might not be able to find one someday and need it. A lighter and 5 minutes to spare. I held a bic lighter to the plastic and waited for it to cook. Remember this is an old filter. First thing to happen was I encountered a slight jet like burn coming out one end. Nothing explosive but enough to wonder why did I do this again, After I got that settled you can hold an open flame to one for about 30 seconds and it starts to deform at about the minute mark they melt threw. It was actually quite amazing must be made from some heat resistant high grade plastic. To further this thought it appeared to creat a very bloated spot before it let go and then only in a spmallish area. I really thing if your engine is that hot you have other concerns than a melting filter.

    Remember I’m a trained professional I would not recommend this for home expierimentation.

    MRLMD you owe me a used filter. I think it was you who ask what if.

     

    #246238
    newkitman
    Participant

    @newkitman

    The issue with the filters and fires was two problems. First the

    location of most filters being above the distrivutor or below

    the coils. Not the best lcation is either end of the filter leaks.

    Second id that the ends leak. And the #1 cause for the leak is

    a poor connection to the hose. Use proper braided hose and

    the correct size clamp, installed properly and securely and you

    should not have a problem. My .02 cents worth anyway.

    Allen Caron
    VW based 53MGTD - "MoneyPenny"
    "If one thing matters, everything matters" - from the book The Shack

    #246239
    Marc Lipsius
    Participant

    @mrlmd

    I have been having this ridiculous problem with my car that is unpredictable, where I may ride for a mile or 5 miles or 20 miles and it stalls just like it runs out of gas. There are no more pieces of black rubber or plastic threads plugging up my main jet, nothing appearing in the fuel filter between the mechanical VW pump and the carb, but I’m wondering if the fuel pump fills with enough air to stop pumping fuel, from the first filter in line before the fuel pump. Both of these plastic filters have considerable air in them and sometimes you can see air rising into the second filter so it has to come from that contained in the first one. All my lines are clamped and there are no leaks. I don’t know why there should be air in the filters anyway, it would seem like it would be pumped or pushed through and come out in the carb.
    I removed the first filter inline and I will see how this affects the stalling situation. If the car runs OK, then air in the fuel pump could have been the problem. If I see no debris at all in my second plastic filter, I may just replace it with the new metal can one I have, for “safety” sake.
    And RW, if you want, I’ll send you the new slightly used (15 min running time) on the plastic filter I took off.

    #246240
    Scott A Chynoweth
    Participant

    @1oldbuzz

    mrlmd;

    by chance are you running a blended fuel(10% ethenol/alchohol) this stuff causes big broblems in the fuel system in a vehical that is not driven regulary.I had this problem last year,long story but a carb rebuils solved the problem as most of the gaskets inside the carb were eaten away.You may have to bite the bullet and run 100% gas.

    And to pga64 the white stuff in the filter could be the same thing,from blended fuels.Had that on my 55,and the tank and whole fuel system was brand new.

    #246241
    Marc Lipsius
    Participant

    @mrlmd

    The whole engine was totally rebuilt, the Solex 34 PICT carb was cleaned thoroughly and what was plugging up the jet after a ride was a 1/2mm x1/8″ piece of either black plastic or rubber. It had to come either from inside the fuel lines, rubber surrounded by braid, also new, or the fuel pump, also new. I don’t know how old the lines were, hanging around in the shop, before putting them on my car when the engine was reinstalled. What would be like that inside the carb?
    This happened 4 times and has not recurred and I don’t know where it came from. I put in the second plastic filter so I could see if it was coming out of the fuel pump. The stuff did not look like the usual varnish or crud from bad stale fuel, and I do use the car almost daily but it still died like it ran out of fuel when I drove it yesterday. That’s why I thought it was air from inside the first filter filling the fuel pump and not letting it pump, so I took out that one before the fuel pump. I have to take it for another ride to see if that solves the problem. The fuel is also fresh but is that 10% ethanol contaminated crap but it runs fine in my other cars, motorcycles, and lawn mower.
    mrlmd40793.7159722222

    #246242
    Mike
    Participant

    @mike-n-scarlett

    Just thinking here, but could this be an electrical problem rather than a fuel problem? Maybe as some componet heats up from engine heat it stops working. Does it have an old coil or condenser? Or an electronic distributor modual. Does it restart after a five or ten minute cool down? Im not saying its electrical over fuel, but anything is possible. I have a plastic filter and you can see air in it to the point you wonder if there is enough fuel in the thing to keep the carb supplied, but it always has.

    #246243
    Richard Wobby
    Participant

    @richard-wobby

    Have you checked Your lines back to tank, Had a very similar prblem would run fine for a few miles and then stall if I let it sit for a while I could get a few more miles it was a load of st in the tank that continually clogged lines.

     

    #246244
    Marc Lipsius
    Participant

    @mrlmd

    There has been nothing caught in either filter.
    Condenser is new. Have no idea how old the coil is.
    It will restart sometimes immediately, sometimes it takes a 5 min rest.
    I have seen air bubbling up into the post pump filter either with the car running or after you shut it off, that’s why I wondered if the pump was getting too much air into it and would stop pumping fuel.
    I have a free flow of fuel by gravity through the lines from the tank back to the engine compartment so I don’t think there is any obstruction in the lines or inside the tank.

    mrlmd40793.9315046296

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