My 07 Dyna has developed an intermittent hot starting problem. The symptoms are as follows:

1) Cold start - never a problem

2) Semi hot starts (after 5-10 mins of easy riding) - not usually a problem

But

3) After a hard run and with the engine fully up to temperature if I shut it down and the bike has sat for more than 5 minutes then when trying to restart, the fuel pump will make this unusual noise while priming and the engine will crank but not fire. The noise can be best described as a short and quite loud 'oink'. It makes this noise once when priming and again a second or two after switching the run / ignition off. If it make this noise when priming then it won't fire - as if there is no fuel getting to the injectors. It only ever does it when the engine if hot and the bike has been sitting, switched off for 5 mins +.

4) If I walk away and get a coffee to let the engine cool down and come back 20 - 30 mins later - it will prime with no unusual noise and fire up immediately.

5) If the engine is hot and I switch off and start immediately, it usually fires with no problem. Its the 'heat sink' of sitting for a while that seems to induce the problem.

It seems to be temperature related and sounds mechanical within the fuel pump assembly. The noise is quite a dry / harsh sound like something binding and is definitely within the tank. Again cold or cool - all is normal.

Has anybody come across this before and what was the fix?

Thanks in advance

 

scot
try pushing up on the petcock(where it use to be)/90 degree fuel fitting under left side gas tank while starting. if it runs . even when hot, its the fuel line inside the tank leaking btw how many miles?
s

 

Thanks Sled.

I'm on 35K at the moment.

 

Scot
Did that work? Mine recently did the same thing. Putting it back together now with a few mods.
Take care
S

 

Sled

Thanks

I've haven't had the chance to try it out properly yet. But will as soon as I have a repeat of the hot start issue I'll try rotating the 'petcock' as you suggest and let you know.

In the meantime - did you have the unusual noise from the fuel pump accompanied with the hot start problem, and what mods have you being doing to sort it?

Coming to the winter in the Scotland now and the bike will be off the road by November. My plan would be to strip things out and do a proper fix over the winter months.

S

 

The noise you describe could be a holed fuel line, but I never heard of one that oinks. Wonder if that could be the pump. A line with a hole usually makes a pissing sound inside the tank if it's not too full. The hole comes from the line rubbing inside the tank so if you replace it make sure it's routed better.
Maybe this will help: https://www.hdforums.com/forum/dyna-...fuel-line.html

 

Thanks Nevil

Yes - I suspected that it might be the pump failing mechanically. But then you would think that if that is the case, that it would be causing problems at other times as well (not just hot starts after sitting for a while).

I was wondering whether it might be vapour building up in the lines while sitting hot and then the pump failing to prime properly as a result - inducing the unusual noise in the process. This might be being caused by a leak in the line as suggested. Thanks for the link.

If anyone else has come across similar symptoms and traced the root problem - any advice would be appreciated.

 

scot
push up the fitting at the fuel tank its a check valve that doesn't allow the fuel to drain out of the tank while shut off. that way you'll overcome the resistance of the spring and vlv and gas will free flow to throttle body. I'm replacing entire fuel pump filter regulator and hoses while I have it apart also lowering kit front forks, new hndle bars, tires brakes, broken speaker, oil temp gage . say hi to all my McKenzie family! sledbum

 

I had the same problem. i would push up on the quick disconnect while cranking and it would start. Disconnected the fuel line at the quick disconnect and sprayed WD40 in the line side of the connector and worked the plunger up and down a few times. No problems since.

Does your noise sound like this? https://dl.dropboxusercontent.com/u/57323637/creak.mp3

For me, one has nothing to do with the other and I haven't found the source of this noise yet. This was recorded over the open fuel filler neck. If anyone can identify it, please let me know!

 

Thanks for the replies.

Ironically, it hasn't done it since I posted this thread - but it will again for sure.

The replies are really helpful. I didn't realise that there was a check valve in the fitting. The valve sticking intermittently would make sense. Heat build up might make it more prone to sticking and if the pump is trying to prime the fuel system against a stuck valve, this may be causing it to make the unusual noise.

Next time it happens I'll try pushing on the fitting as suggested, If this works then I have it nailed thanks to your input.

I couldn't play the audio file - but thanks for sending anyway.

I'll post back if this is the fix.

Thanks all