Noob here needing some help...

Hello all...

I have a 96 T-10 with the W code 4.3 and Im getting code P0446. The truck has been running fine with the light on until about a week ago. It did not want to start after sitting overnight or at work all day. Once I do get it started, it runs fine and restarts are normal.

Doing some checking on the code, it comes up as "EVAP Emmision control system Vent Circuit malfunction"

I have read that there is some sort of valve that gets clogged but I cannot get anything more specific

Can someone shed a little light on this for me please? It would be greatly appreciated...

P0446

Purge Selenoid Valve, Located on the middle right side of the rear axle, Drop the spare tire down and you will have a clear view. Very easy to change out.
Also don't forget to replace your gas cap with a new one. Clear the code's when finished replaceing everything...
Good luck.

P0446

Purge Selenoid Valve, Located on the middle right side of the rear axle, Drop the spare tire down and you will have a clear view. Very easy to change out.
Also don't forget to replace your gas cap with a new one. Clear the code's when finished replaceing everything...
Good luck.

Thanks DINO...

Would the failure of this cause the hard, cold starts?

No, it would not cause starting problems, When was the last time the truck had a COMPLETE TUNE UP?

No, it would not cause starting problems, When was the last time the truck had a COMPLETE TUNE UP?

This past summer...

AC Delco everything. Plugs, cap and rotor.

The truck has 174K (mostly highway miles) and runs great. Gets about 21-22 mpg consistently and uses very little oil. Been and damn good truck :smile:

This hard starting has me baffled...:screwy:

Have the battery checked with a load type tester. AutoZone will do it for ya. When a battery gets a little weak the starter takes all the current and there is not enough current left to get the fuel pump up to max pressure for cold starts. (i.e. after sitting all night or all day)

Also, check and clean the battery cables and check max fuel pressure.

Let us know what you find.

I own the same year/model and now have about 185,000 on it. I had to replace the start switch a couple of years ago, heard it was a common problem. I've seen the same issue on other strings in this forum. Good luck.

Most often the cause will be overfilling the tank.

Only top off to the nearest dollar after it kicks off.

P0446

Purge Selenoid Valve, Located on the middle right side of the rear axle, Drop the spare tire down and you will have a clear view. Very easy to change out.
Also don't forget to replace your gas cap with a new one. Clear the code's when finished replaceing everything...
Good luck.

DINO,

According to the dealer, the purge solenoid valve is up on the intake. Are you sure on the description of this?

TIA!

Have you replaced your fuel filter lately?
Has the fuel pump ever been replaced?

Fuel filter was done last summer and I've never changed the fuel pump.

When you start the truck, turn the lock cylinder to RUN and wait to hear the fuel pump before cranking the starter. That may either help the situation or at least help diagnose it.

If you get into a routine on start up - Turn the key to RUN, watch the MIL for the "bounce", wait for the pump to cycle and build pressure, and then crank to start - you may have a better handle on what's happening.

Fuel filter was done last summer and I've never changed the fuel pump.
If you have changed your filter regularly your pump is probably fine.

As far as the code, it could be many things. The best suggestion that I can make at this time is to check out any and all hoses that connect to anything in the EGR department.

I tried searching my documentation for my 1995 but cant find anything specific. Most of what I find on the net says that it means there is a leak in your EVAP system somewhere.

Hopefully its just a cracked or damaged line.

When you start the truck, turn the lock cylinder to RUN and wait to hear the fuel pump before cranking the starter. That may either help the situation or at least help diagnose it.

If you get into a routine on start up - Turn the key to RUN, watch the MIL for the "bounce", wait for the pump to cycle and build pressure, and then crank to start - you may have a better handle on what's happening.

Already do that. I listen for the fuel pump relay to click when it cycles off. If it's warm out, it's starts with just a bump of the starter. It started the hard cold starts soon after it got cold. A couples weeks back, it was in the 50's and it did fine. It starts fine also after driving it as long as the engine is at least warm.

I honestly think the CEL and hard starting are two different issues. I put a new AC Delco gas cap on it today at lunch and cleared the CEL. We'll see if that cures the CEL issue.

Thanks for the input guys. You've been a big help. :smile:

Oh, I didnt realize that the Check Engine Light was already addressed.

I wonder if the Intake Air Temperature sensor has anything to do with it.

****UPDATE****

Well, looks like the CEL iss ue is cured with the new gas cap. :grinyes:

This morning it was around 12 degrees out. Needless to say, I was dreading trying to get it started because of all the problems it has when it's cold. Anyway, I hit the key to the "run" position and low and behold, the fuel pump sounds normal. Relay kicks off, I hit the key, and fired right up. Previously, I noticed that it had begun clicking instead. So, I think a fuel pressure test will reveal a failing pump. :banghead: Not bad I suppose for 175K :grinyes:

Thoughts?