Engine cranks over but won't run when hot

Discussion in 'Engine, Fuel and Exhaust' started by sledbum, Feb 9, 2013.

  1. sledbum

    sledbum Member

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    Used 07 Road Glide 30K milesRinehart out, stage 1 in, race tuner, battery less than 1 yo, no codes or CEL, fuel pump and light come on then a few seconds later turn off consistently. Daily driver starts/runs fine going to work and at end of day going home, cold start. Recently after good warm up ride 20- 30 minutes short quick stop and go for gas, groceries etc. Bike won't run. Cranks ok, cycle main and ignition switch no joy. Try several times over 15 minute period and cranks fine just won't fire. Wait 2-3 hours it cools down and runs ok.

    I can repeat problem and here is some of the things I tried. Used a multi meter that has an amp clamp and put it around the spark plug wire. Running it reads 27 hz, when it's hot and cranking it reads 20 to 27 hz but won't run also the tach is showing rpm. Also sprayed a little starting fluid and the bike ran for the few seconds but would not run on it's own. I'm assuming spark is ok at this point.
    Removed air cleaner, cleaned and inspected IAC, it moves with switching ign. on and off both cold(when bike starts ok) and hot when problem occurs. Looking in intake and revving throttle I can see fuel vapor. While trying it during no start I don't see fuel but the engine is not turning over as fast as it is during normal revving. I'm assuming no fuel.

    So, leaning toward fuel side for problem. Could injectors not be working electrically and not throw a code? Could injectors or any part of fuel system not flow fuel when hot? How can I test injectors pulse width, or duty cycle electrics both when it's running and when the problem happens? How can I check injectors mechanically of they are working? Looking into getting fuel pressure test gage but it does make noise whether hot or cold, don't think that's an issue. Is there anyway of checking ECM for ignition/injector signals that I can compare when running ok and when it fails hot?

    Any suggestions, comments greatly appreciated and I hope I didn't put you to sleep after rereading this long winded story.

    Thanks in advance

    sledbum
     
  2. Jack Klarich

    Jack Klarich Expert Member

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  3. Hoople

    Hoople Account Removed

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    I would confirm that if you spray fuel in throttle body it will start the engine each and every time. Once you know that, it will make it alot easier to nail the problem down. Use gasoline and not starting fluid for this test. A hot piston and compression is all that is needed to ignite ether which can lead to misleading results.

    The amp clamp test is erroneous because that reading your seeing is in cycles per second, not cycles per minute. So 20 X 60 = 1200 X 2 is 2400. The engine isn't going 2400 rpm during cranking. I don't know what the meter is seeing, but it can't be actual secondary output.

    To answer your question about injectors.,,, Injectors can fail to open and it still will not throw a code. DTC software will only catch open or shorted injector drive lines. .You can read pulse width of the injectors using a Super Tuner dongle w/ SE software or by using a break-out box and scope directly at the ECM. But that only tells you that the signal was sent to the injector. Seeing the electrical pulse does not mean fuel actually was injected into the cylinder.

    Pump noise doesn't tell you much about fuel pump pressure. Pin hole leaks in the lines on the output side of the pump (within tank) would kill your pump pressure and you would still hear the pump cycle..

    Check the chrome fuel quick disconnect at the tank. There are two built in safety check vales that may not be releasing. Disconnect and re-connect the chrome connector at the tank when the engine fails to start, not before you go out on your ride. Using your hand,, press in on the male portion while cranking to force fuel release.

    First step for me would be to confirm with certainty, that adding fuel starts the bike each and every time. You can check for spark, but you must leave the spark plugs installed in the engine. Use an extra 3rd plug and connect the coil wire to it. Place the plug body against the engine and crank engine. Gap this test plug to .050".

    BTW, nice job on giving complete details of your problem.
     
  4. sledbum

    sledbum Member

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    hoop
    thanks for the suggestions, before i took off i replace all the right side fuses and checked the ecm plug all ok. installed a timing lite andchecked both pluq wires, i'd be curious if there is a non messy timing mark but i was just checking for fire ok.
    road test, let it sit for few and tried tostart no joy, installed timing light worked both front and rear, sprayed gas while cranking and it ran till i stopped spraying. kinda verifies spark ok fuel not ok. reread your post went back out to garage and pushed in male portion and hit start button fired right up. going to get fuel test gage set...................woohoo you are my new favorite hero! just went out and hit starter button and it would not run, then i pushed in quick connect on tank after starter was engaged and motor fired and stayed running.

    now do i still need to check fuel pressure? whether hot or cold fuel pump will run and shut off after a few seconds. or just replace the fuel tank valve assy?

    thanks hoople the hero

    s
     
  5. Hoople

    Hoople Account Removed

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    I think the 10% alky in the fuel swells the o-rings in the HD adapter and it causes the quick disconnect to choke off the fuel.
    Low or high pressure won't throw a code. Low pressure can eat you up by running lean across the entire RPM band. The gauge also allows you to check for bleed down pressure. The pre-made adapters by Mac Tools & Jim's Tools are crazy expensive, but you can make your own for about $60. With the tool you can check fuel pressure in 5 minutes. It's something I check every so often even if the bike is running ok because it's just too risky not to know.
     
  6. sledbum

    sledbum Member

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    installed gage will pump up to 56 psi and fall down to nothing right away. new one going in this week

    thanks again hoople

    later
    s
     
  7. Hoople

    Hoople Account Removed

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    "New one" meaning what? Hope you don't mean a pump. If you have a good pressure value, it may just be a pin hole leak in the discharge tube. Could also be the pressure regulator O ring leaking. The few psi your short just may be from a leak.
     
  8. sledbum

    sledbum Member

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    with 30k going to change filter kit and hoses and seals and regulator, if pump is making pressure shouldn't it be ok?
    thanks
    s
     
  9. Dr. Dolittle

    Dr. Dolittle Experienced Member Staff Member Moderator Contributor

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    Agree with Hoople - doesn't sound like you need to jump the gun and get a new pump yet. If it builds up to proper pressure AND THEN leaks down, this implies a leak somewhere downstream of the pump.
     
  10. Jack Klarich

    Jack Klarich Expert Member

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    Agree with Hoople here, if the pump was at fault it surely would not create this kind of pressure, I too would be looking at pin holes in the lines and the regulator JMO