92 240sx cold start injector fail?

[alexh]

Starting as long as 5 years ago, my 240sx would be very hard to start when completely cold. It might take a few minutes to start and then ran rough for a few minutes. As I crank it, you can hear it just barely firing and it slowly gets closer to firing with additional cranking until it finally sputters to life.

This only happened a few times in several years but it's been happening almost every week now. When it does not start, I have verified that there is a spark and there is a faint smell of gas at the tailpipe. Once it's running all is fine.

I have always suspected the cold start injector (could be wiring also of course) but since the injector appears to be a dealer only item and I can't even see it I like to get some other opinions. I suppose I could pull it out when it fails to start and verify operation but it's not really practical.

Thanks

[alexh]

Well, this is embarrassing. I just checked the FSM and apparently there is no cold start injector on this car. I'm going to attempt to go through the diags in the FSM under hard to start when cold but any other suggestions in the mean time?

For cold start, the engine either needs more fuel or less air. How does the 240 do this?
Modified by alexh at 9:17 PM 11/8/2007

[vancouverbc]

there is an air regulator that supplies extra air until car warms up. i forget how it knows it is cold. it might be the temp sensor that feeds temp data to car computer. squeeze the hose branch that supplies air to air reg when it is cold. if it makes no difference to idle, you know it has failed to open.

http://img265.imageshack.us/my...9.jpg

[alexh]

Thanks,

I did some more reading of the FSM and although it does not really say much specifically about cold start apparantly more air is provided by the air reg as you said and the injectors all fire simultaneously as opposed to multiport mode when the engine is cold to provide more fuel.

I'll also check the resistance of the coolant temp sensor. Odd that they don't have the coolant temp sensor as part of the cold start diag procedure but I don't think I have ever found any problem by using the FSM diagnostic procedures. And I have had quite a few odd problems on this car

[vancouverbc]

make sure you test the right sensor. there are two.

zerothread?id=254375

i have had problems with trouble shooting guides in fsm, too. they do have some basic procedures you go through first before doing the main trouble shootin.

Thanks,

I did some more reading of the FSM and although it does not really say much specifically about cold start apparantly more air is provided by the air reg as you said and the injectors all fire simultaneously as opposed to multiport mode when the engine is cold to provide more fuel.

I'll also check the resistance of the coolant temp sensor. Odd that they don't have the coolant temp sensor as part of the cold start diag procedure but I don't think I have ever found any problem by using the FSM diagnostic procedures. And I have had quite a few odd problems on this car

est

[driftingmy240sx]

you may want to check your fuel pressure also. i recently worked on a maxima with the same problem and found that the fuel pump was unable to build enough fuel pressure to statrt the car easily.

[alexh]

Drifiting or others,

Saw your post but I was busy replacing my IACV

As far as the fuel pump goes I need to rule this out or in because the last time this happened I could not start the car at all. Funny thing is, the next morning I put the key in the and it started right up! As I said I verified spark was present.

The manual says to squeeze the fuel pressure line to feel if it's pressurized. I'll give that a try but it seems like something a little more scientific might be better.

I also noticed that there is a relay for the fuel pump - I'm wondering if this migt be more likely the problem since it seems to be an all or nothing failure. Also, it's only a $12 part.

Thanks for the reply.