Won't start cold--Ideas?

[mikec03]

I have a 95 subaru, 2.2 engine, 198K. The engine will crank but won't fire as temperatures drop below 25 degF. No Cels. This has been going on a couple of years. I've change the temp sensor, plugs, coil and wires. I've checked for vacuum leaks. The acceleration and driveabilty is fine so I think that the electrical must be OK. I've tried priming the gas rail, by repeatedly turning the key on/off, before trying to start thinking that the back pressure regulator is leaking.

 

I suspect that it's not rich enough fuel/air ratio at cold temperatures, so that's why I changed the temp sensor. Maybe the wiring from the TS is bad, but the connector looks good. The only clue is that even in warm weather, I need to depress the accelerator on starting. On my other two subarus, I can just turn the key and they start.

 

I don't what to check now? I could pull the plugs and look at them for clues? I don't smell gas so it doesn't seem too rich is the problem.

 

Give me an idea.

[Legacy777]

It could be your fuel pump or fuel pump wiring. I'd suggest putting a gauge on the fuel system by the fuel filter and see what your pressure is like.

[Fuzpile]

After the various things it should've lit a CEL. There is a thing about this ECM, a section which is a "learning control" area. This effects the bypass air control valve throttle valve and sensor. if I read this right it's a loop which on the other side passes thru the igniter to the coil. So theoretically anyone of these disturb the loop. A scan tool proper for a Subaru OBD2 should pick up codes associated with one or more of these problems. That's all fine except most likely you can disconnect the battery for 15-60 mins and some will reset and it may start. It's important to see what they are before clearing them because it will likely return.

Edited December 13, 2010 by Fuzpile

[mikec03]

Update:

 

I started the car this morning on the third crank [about 3 sec/crank] by pressing the accerator most of the way down. It's 6 degf here. What am I doing when I press on the accerator other then opening the throttle?

 

I have been looking at pressure gauges for the gas. Unfortunately, that year, Subaru didn't have a pressure tap on the rail so its a pita.

 

I should have said in my original post that the car fires weakly below 25 degf. And the lower the temperature, the weaker it is. Sometime it starts after 10 or so tries but by then the battery is run down and a jump is needed.

[naru]

Update:

 

I started the car this morning on the third crank [about 3 sec/crank] by pressing the accerator most of the way down. It's 6 degf here. What am I doing when I press on the accerator other then opening the throttle?

 

I have been looking at pressure gauges for the gas. Unfortunately, that year, Subaru didn't have a pressure tap on the rail so its a pita.

 

I should have said in my original post that the car fires weakly below 25 degf. And the lower the temperature, the weaker it is. Sometime it starts after 10 or so tries but by then the battery is run down and a jump is needed.

 

You are cutting off the fuel supply by cranking w/the throttle floored.

Your symptoms fit those of a leaky injector.Usually worse warm,but,anything is possible.

 

Might want to check the TPS too.

 

Try disconnecting the CTS as well.

Edited December 13, 2010 by naru

[firstsubi]

What ever happened with your problem? Get it figured out?