2 wire connector coming from under kelsey hayes electrical loom

[alvaroemg]

P0440 is a "large" EVAP system leak. Which is kind of good news, should make it easier to find than a P0442 (small leak).

Any suggestions where to start or what to look for?

 

[df2x4]

Any suggestions where to start or what to look for?

A smoke test of the EVAP system would be the best diagnostic approach IMO, but it wouldn't hurt to give all the EVAP solenoid connections under the hood a check just to make sure everything is connected properly. I had an issue in my red '97 where it threw an EVAP code intermittently and it turned out to be one of those connections not being fully seated. The line would bounce up and down slightly while driving and create the leak.

If all of that looks good and you want to try a cheap parts cannon attempt, you could replace the gas cap with a new one. I've fixed a couple of EVAP issues on different vehicles over the years like this.

 

[east302]

Here’s the diagnostic from a 1998 manual. It’s probably close enough (if not the same) for a 99, but the 99 manual has been uploaded to this link under post #77 if you want to check:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[alvaroemg]

Thank you guys for the prompt replies.

The following day after encountering that P0440 code, prior to taking off to work, I cleared the CEL and took off. Code never came up again. I've been driving my truck locally and it drives fine. I hear the air pump running when I turn on the truck. Must of been pumping dirt and moisture sitting in the pipes and hoses prior plugging it back in. Who knows how long it was unplugged for.

Only code I'm getting is a Cyl 2 misfire. Sometimes it turns to a multiple cyl. misfires. I'm 100% cyl 2 is the root cause.

I'm still on the factory injectors. Been looking at upgrading to the new model but I would hate to dump $370 and for my misfire to still be present.

I'm getting a test fuel pressure gauge on Friday, starting with that. I've read pressure should be 60psi with the key to on position.

 

[someotherguy]

Thank you guys for the prompt replies.

The following day after encountering that P0440 code, prior to taking off to work, I cleared the CEL and took off. Code never came up again. I've been driving my truck locally and it drives fine. I hear the air pump running when I turn on the truck. Must of been pumping dirt and moisture sitting in the pipes and hoses prior plugging it back in. Who knows how long it was unplugged for.

Only code I'm getting is a Cyl 2 misfire. Sometimes it turns to a multiple cyl. misfires. I'm 100% cyl 2 is the root cause.

I'm still on the factory injectors. Been looking at upgrading to the new model but I would hate to dump $370 and for my misfire to still be present.

I'm getting a test fuel pressure gauge on Friday, starting with that. I've read pressure should be 60psi with the key to on position.

Spec is 60-66 psi; if it's a little bit low you can get intermittent no-starts or possibly random/multiple misfire codes. If you upgrade to the MPFI (8 individual injector) setup it seems like the operating pressure is a bit lower. Fuel pressure seems to be less critical at this point because you're not depending on the 60-66 psi that the central injector setup requires to force open the poppet valve junk.

Richard