08 Mastiff Need some help.

[Joe Gunn]

First off this is my first BIG DOG, so far a love this bike, always wanted one. Had a deal fall in my lap I could not pass up, also have a 14 Street Glide . Well I picked it up last week, had to fix air ride, changed all fluids out, replaced plugs. Was ready for the first ride. I went to top off tank first, then headed to show her off at first watering hole, all was good. After leaving first stop, half way down the road the bike just dies, would not restart, just turning over like it had no fire, or fuel. The fuel lever was towards the rear of the bike, not really looking at it I just moved it back towards the front, bike started right up. Made it home as I was opening door it died. Tried to restart, same thing as earlier. I let the bike sit about a hour went out and it started right up. They did not have the plug I wanted at Auto Zone, so I put the cheap Champion plug in it until I could replace later. Question is could the cheap plugs be a issue? Thought maybe it was vapor locked, tank was very full, but why would it start right up after I moved fuel valve? Any help would be appreciated. Buying a Manuel next...

 

[Th3InfamousI]

Does it die like the power is off? Or are the lights still on?

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[BigDogBro1]

Maybe the gas tank cap vent is not open or plugged. Could be the petcock has some blockage in the RUN position. Do a search on the subject. You may also want to do an introduction if you want any help.

 

[cdogg556]

Mine did the same thing when I first got it, rode about 5 mi and it just died, waited about 10 min and it fired right up, got home and it died, checked the battery and found that it was bad and not holding a charge, these bikes run directly off the battery so as soon as you drop below 12.6 volts or so it will die, I replaced it, bought a Multi Meter and checked the voltage regulator/stator to make sure they were good and I was good to go until the voltage regulator burned up on me recently, I would change the VR also since Big Dog used a cheap chinese one, Curtis at WSW will have everything you need!

Also, do an intro or you'll get crap for not doing one!

 

[BWG56]

Maybe the gas tank cap vent is not open or plugged. Could be the petcock has some blockage in the RUN position. Do a search on the subject. You may also want to do an introduction if you want any help.

X2
Also, do an intro or you'll get crap for not doing one!

 

[Joe Gunn]

Forgot to mention I did put a new battery in, Thanks for the advice so far. Will do a intro. Thanks guys.

 

[bearman]

I doubt cheap plugs could be the issue, but that's easy to check, and you already know how.

If it acts like its running out of gas then I would first pull the fuel line from the carb to see if you are actually getting gas out of the petcock in both the run position and the reserve position. If it is getting fuel to carb then check for venting by opening the cap next time it dies.

If it dies like you flipped a switch then it is probably not fuel related. Since it is turning over but no fire, my guess would be that it is NOT the key switch. My guess as to what it COULD be is the crank sensor. They seem to quit intermittent at first (when hot) then quit altogether. To check the crank sensor check if the yellow and blue LED's are blinking on the ignition module. The red one should be on after you hit the run button, then the yellow and blue should blink when the motor is turning over. If they don't blink the crank sensor is bad.

 

[pauldeepsea]

I doubt cheap plugs could be the issue, but that's easy to check, and you already know how.

If it acts like its running out of gas then I would first pull the fuel line from the carb to see if you are actually getting gas out of the petcock in both the run position and the reserve position. If it is getting fuel to carb then check for venting by opening the cap next time it dies.

If it dies like you flipped a switch then it is probably not fuel related. Since it is turning over but no fire, my guess would be that it is NOT the key switch. My guess as to what it COULD be is the crank sensor. They seem to quit intermittent at first (when hot) then quit altogether. To check the crank sensor check if the yellow and blue LED's are blinking on the ignition module. The red one should be on after you hit the run button, then the yellow and blue should blink when the motor is turning over. If they don't blink the crank sensor is bad.

Agree could be crank sensor or may want to drop the carb bowl to make sure it's not clogged?

 

[Th3InfamousI]

He never answered my first question wether the bike dies like the power goes off headlights etc or just dies like it's starving for fuel

Could be a number of things but that info would help. As one would be purely electrical issue and the other is fuel/spark related.

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[Joe Gunn]

Thanks for the reply, will check tonight. As far as the light still on, did not check. Speedo light was on I remember seeing neutral light. I was on a narrow road when it died. Since gas was the last thing I put in, I just flipped switch and it started right up. Thanks for help guys...

 

[Joe Gunn]

really acted like it was vapor locking, will check vent and petcock first...easiest place to start, since bike has been sitting a while could be the issue.

 

[ground pounder]

If your cap still has the white check valve screwed into the cap at the bottom. Take it out as they were notorious for causing vapor lock!!! It just unscrews.

 

[francoblay1]

Well????????????????

 

[Joe Gunn]

Looks like it was just the cap,(Vapor Lock) rode all wkd with no issues. Checked the crank sensor it was good,but I did buy a spare. Appreciate all the advice. Ride Safe.

 

[Dragonslave]

Good to see you found the problem. It sounded like vapor lock to me. I was going to recommend removing your gas cap when it occurred again. If it fired, then that was your problem.

Its always best to start with fuel when problems start as it seems to be the most common & easiest to diagnose issue.

 

[cdogg556]

You ever pull your fuel line off to drain the tank and watch the flow coming out of the line? It's amazing how much more volume you get when you remove the gas cap! That's what sold me on the vapor lock thing, I removed the white plastic thing from the gas cap and now no more restriction!

 

[BWG56]

With that check valve removed I had vapors from the vent hole, now that the check valve was removed, escaping from under the cap and it got under my paint saver and bubbled the paint. I had the tank replaced and painted under warranty and it did it to the second tank also. Without getting into it, that's where I picked up the name "Hammer and chisel" cause they epoxy'd the paint savor in. I had the tank fixed and I am running right know and have been for over a year with the check valve still on the new cap without problems and I have never seen vapors or gas on the paint savor when I take the cap off. Bottom line, watch to see if you have vapors on the paint savor when you remove the cap to fill up.