2008 Hertiage Classic - Spray in Tank

Discussion in 'Engine, Fuel and Exhaust' started by flashinco, Aug 30, 2012.

  1. flashinco

    flashinco New Member


    I've been working on trying to figure out why the bike has been hard to start, and having constant hesitation/back fire issues when practically any amount of throttle is applied. Thanks to the many posts so far, I've started to narrow this down to the spray I've been seeing in the tank.

    After taking the tank apart to inspect the hoses, I found that the bypass value on the fuel filter is spraying. I understand that when the bike is primed, that should be normal (Please correct me if that is not right), however when I start the bike it continues to spray. If I apply throttle, the spray still does not stop.

    I am under the assumption that this shouldn't be happening, and explains why the bike is starving for gas. Is anyone able to confirm if this is the case? I just want to make sure before I head up and start buying parts from the local dealership.

    Many thanks

    BUBBIE Well-Known Member


    When turning ON the ignition, the fuel pump pressures up Once.

    Turn it off Without starting,,,,,, Wait for about 10 seconds and turn it back ON... IF you hear the pump cycle again It is A Leaking Down problem.

    Leaking, the pump Can't keep the pressure needed to operate the volume of fuel needed. YEP that is your problem...:bigsmiley23:

    Spraying in the tank Might be a hole rubbed in the plastic line. A NOT uncommon problem.

  3. flashinco

    flashinco New Member


    Thanks for the reply. Just tried out what you suggested, and the pump did cycle a second time. Last night I did take out all the hoses, inspected everything, and before screwing down the tank cover, I was able to watch fuel spray out of the bypass value on the fuel filter housing. As I started up the bike, spray kept coming out of the bypass value, so I'm suspecting that this is my pressure issue.

    The hoses looked good, the bike has only 3k miles on it, and I've been itching to get some riding in this year.

  4. cool breeze

    cool breeze Active Member

    I'm not sure about the softail but if it has a filter shell like the touring model check the top of the shell and the mount base it may be eggshaped and not sealpng at the o-ring it needs to hold 60 lb of fuel pressure to run right
  5. RibEye

    RibEye Junior Member

    The fuel pressure regulator will bypass fuel back into the tank most of the time the engine is running. The fuel pump is a single speed pump. The pressure regulator will maintain the uniform pressure by bypassing all pressure beyond that. That would be the spraying, while running, from the filter area.

    There is no pressure sensor. It does not turn off the pump when pressure is good. The brief period of pump operation, when first turning on your run switch, is to guarantee required pressure in the fuel rail. The failure to detect engine running (crank position sensor) causes the fuel pump to shut off. It starts back up and runs continuously when the engine is detected to be running. While running, you will always see bypass fuel coming out of the pressure regulator at the end of the filter, except maybe during wide open throttle (doubtful since you want consistent fuel pressure, especially during heavy throttle).

    The ECM apparently has a delay period between priming pump operations, so you do not see a repriming until a period of time has passed since the last priming operation. This is not due to pressure leak-down. Again, there is no pressure sensor. It would be nice to actually have a pressure sensor, because pin-holes in tank lines, clogged filters, pump fails, etc., could all be detected.

    This information is based on my knowledge of the 2003 EFI systems. It is possible that a pressure sensor has been added for newer vintages. Someone else can chime in with that info.

    Good luck,
    Rich P
  6. tourbox

    tourbox Senior Member

    I agree with cool breeze with the mounting problem.A friend with a '07 Dresser had the same problem. It turned out to be the mounting/holding bracket for the filter/reg. assy.. It was a plastic set up that held it together. 2 of the legs of it were cracked causing everything to be offset and leaking into the tank. The soft tail pump is different but I would look at what and how the reg/filter assy. is held in place.What RibEye says could also be true. I have never watched for bypass spray while running.Excess pressure has to go somewhere,just never thought about it.