My WAG is a defective fuel pump or fuel pressure regulator. After turning off an EFId engine, the fuel system should retain highfuel pressure for 30+ minutes and fuel under high pressure will not boil easily. However, if the pressure immediately drops when turned offdue to the fuel pump's check valve or the fuel pressure regualtor leaking down the pressure, the fuel in the hot injectors and housing will easilyboil. The next time you go to start the engine, the air pocket created from the boil has to be purged out before the fuel willflow thru the injectorscausing a hard start.I think a fuel pressure check is in order, especially your bike's ability to retain pressure after engine shut down. I run apermanent fuel pressure guage on our bike which really helps to narrow down the possibilities in case of engine problems.

 

I am beginning to understand all the symptoms and causes of a vapor lock and I don't believe that that is what is going on here. It is fuel injected and has always run as good as any stock bike should run. I don't think I have a fuel pressure problem because it always performs well (as good as any stock bike should). It is just an odd and very rare situation. Easy to get running but it just shouldn't happen. I will have tools with me if I make any overnight runs.

I will soon be taking it to my mechanic for the 20K tune up and I'll bounce it off of him. I will post anything he has to offer.

Thanks.

e¿e

 

Well, it's fixed. Although it seemed to be a heat related problem, it turns out that it was the cam position sensor. It got to the point that I had to take it into the shop when we were in Sturgis 2010. I took it to Dakota V-twin. I lost 1 day of riding but it was worth it. So now, a year and a half later, it hasn't had any problems. Looking forward to riding to Sturgis again this year.

Thanks for all the input.

 

I know vapor lock, I have panheads with steel fuelines which run close between the cylinders.
The fix while riding is to open the throttle all the way and go full choke, the vacuum will pull anything through the lines and into the float bowl ( which is vented) if parked, crack the gas cap and blow into the tank.

What is done above is to push the vapor though the lines--- which is what a fue pump does on an efi system.

Those techs failed the test, you can exclude them from ever touching your bike--- all they can do is swap parts until something works ( and charge you for parts you may not need).

The fuel delivery system may need to be serviced. clean filters, check injectors and seals and check that fuel pump is making and holding pressure in the lines.
Crank-sensor...

Mike

 

Thanks for the follow up. I, for one, appreciates it when someone puts an end to the story. This way, if someone else has the problem and does the search they also find the solution.

Give this man an "Atta boy!".

 

You can still get vapor lock with EFI systems. Winter grade fuel on a hot day can vapor lock even at 40psi of fuel pressure, the fuel is too volatile. It just happens far less often on EFI since it is harder for the fuel to vaporize at higher pressures.

 

Even so, if vapor is trapped in the lines, as the motor cranks and the pintles open, the vapor should be pushed through the lines quickly by the pressure of the fuel pump
It shouldn't lead to a "no-start"condition

Living in PHX I see hot days- our summer grade is up to 10% ethanol, winter is up to 15%.
higher percentages than much of the country, higher temps too.



Mike

 

It can definitely lead to starts/stalls and hard cranking until the temp in the rail & injectors is brought down low enough to where the fuel is in liquid form again and it's not boiling anymore. I don't think it happens on Harleys too much, but it definitely occurs in cars. It also wasn't the OP's problem.

The fuel you get in Phoenix has much lower RVP values than fuel that I get in Michigan, as an example, regardless of ethanol content. It's done so it doesn't evaporate as quickly when sitting in the fuel tank for extended periods of time. It's actually more of an issue in the midwest where the temp swings are more substantial between winter and summer, and the higher RVP fuel is required for cold starts.

 

It usually happens during intercourse when you call her Betty, and her name is Sandra. Sorry could not resist.

It is always a vent issue, not enough air going into or out of the tank.