Experienced the "hard starting" today

[Jack_Shaft]

Since reading up on this topic here on TY, I had to check out this claim for myself at the local dealer. Sure enough, even after allowing the fuel pump to run up to provide fuel pressure, we had to crank the thing for about 8s before it caught and then ran. That was divided into two periods of 4s each in an effort to not damage the starter. My RX-1 takes about 2-3s to start, anytime (other than after storage) unless I was a moron and flooded it.

After speaking to the mechanics at the dealership, I have my theories on this one. I would imagine that this engine has a decompression system and if it does, it is quite possible that the engine requires a few cranks before the engine is adequately decompressed. At that point, the engine can crank over faster and is more likely to catch. It is also feasible that only at the point that the engine is spinning at this decompressed (and thus, higher) rpm will the EFI allow fuel to enter the combustion chamber and then ignite.

That's my theory. I have no idea about whether this engine has decompression or not, perhaps I'll ask at this weekend's show.

 

[ZAKSTANG]

so u got it started after the second 4 second try??? not sure that is a problem at all or can be considered "hard starting" im a huge yami fan and dont think thats a problem at all...shouldnt hurt the starter at all to turn over for even 10 seocnds but i could be way off...enjoy your seld, hope to have one soon....

 

[BV1]

Break it in, mine is easier to start now then when I first got it.

-Steve

 

[phaz4]

mine is 4-5 sec cold. it cranks for 3 seconds then starts to fire. you have to continue to crank another 1-2 sec to keep it running.

 

[NH Rider]

The engines will not run until there is sufficient oil pressure. That's why cold starting takes much longer than hot starts.

 

[actionjack]

The engines will not run until there is sufficient oil pressure. That's why cold starting takes much longer than hot starts.

This is exactly what the dealer told me when I was there checking out a Phazer. The first time it took about 10s to start, then we started 4 or 5 times quickly. Nothing to worry about.

 

[redsnake3]

jackshaft, i think a big part of the problem with the sled on the showroom floor is that starting it up for 20 seconds at a time we are starting to fowl or load the plugs. i am sure if the sled had a chance to have the throttle opened up for a little this would cure it. the 700 grizzly we have was doin the same thing until we took it for a little ride, then it cleared right up.

 

[MrSled]

well, I guess I will have to take it for a ride snow or not

 

[barnstormer]

When I picked up my phazer FX the dealer had just gotten back from the tech school and he warned me about this "hard start". The fuel pump thing does nothing according to him from a cold start. The Phazer is the first sled to have a new engine protection system. It will not fire an injector till it reaches a certain oil pressure. Once it warms up it starts quick because the oil is warm.

 

[Mikey]

Remember that A fuel injected sled will run upside down so thats for sure the reason for the oil psi switch. No float bowls to drain or keep filled. Myself I would rather have A hard start condition than A run upside down engine that ran outa oil...Can you say complete bearing replacement!

 

[FastEH!]

91 Oct feul..right! The wrong feul may result in hard starting?

 

[Jack_Shaft]

When I picked up my phazer FX the dealer had just gotten back from the tech school and he warned me about this "hard start". The fuel pump thing does nothing according to him from a cold start. The Phazer is the first sled to have a new engine protection system. It will not fire an injector till it reaches a certain oil pressure. Once it warms up it starts quick because the oil is warm.

If this is the case then my theory is correct, but instead of the deciding factor being the engine RPM, it's oil pressure, which also takes a few cranks before it's at an acceptable level when the sled has sat for a while.

Interesting. Thanks for the post.

 

[Jack_Shaft]

I am waiting for the Yamaha Tech school to verify this...

 

[Thrusted Vector]

The decomp is run off the exhaust camshaft and is activated by a pin opening the exhaust valve below 700 rpm,The camchain tensioner is activated by the oil preassure.

 

[Srxspec]

The engine cranking for 6 to 7 seconds before firing is normal at this time. It is due to the oil pressure being built up.