Long crank time on cold start

[WR450rider]

Looking for some help/advice: My 87 GN w/47,000 miles that I bought new has a problem w/long crank time on cold start. Over the past year I have replaced the injectors w/green stripes, fuel pump, plugs, etc. This seemed to start when I replaced the leaky stock injectors w/the new ones. Before the car would fire off quick if it had sat for more than a week. If less it would be a dirty start with black smoke. Now it just turns over for what seems like a long time when cold. Hot starts are quick and clean. Any advice would sure be appreciated.

 

[ijames]

Watch the oil light and see if it fires off right after that goes off - if so, your fuel pump relay is bad.

 

[seeyabye]

I agree, if you turn the key to the run position and don't here the fuel pump come on for two seconds, replace the fuel pump relay.

 

[WR450rider]

Fuel pump relay is working fine. I have fuel pressure at the rail as soon as I turn the key on.

 

[ijames]

How fast does the fuel pressure drop after you shut off the engine? It should fall maybe 5 psi in a couple of hours, or much slower. Could be pump check valve (but yours is pretty new), leaky injectors (but again, yours are new), or fuel pressure regulator not sealing off. In my limited experience big differences between cold and hot starting are fuel related. However, it can take the cam sensor up to two full engine revolutions to sync up so the engine can fire, so on average it will take one revolution. Don't laugh, but how is your battery and starter? The starter slows down a little each day but it happens so gradually I hadn't realized how slow it had gotten until I replaced my starter the last time and I thought the car woud flip over the motor was cranking so fast . Maybe yours is dragging some, especially when the motor is cold?