Emissions Problems with my 94 ZR2

[Trucks!]

OK guys, ive been reading some pasts posts and you all seem to know what you are doing. I have a 1994 S-10 standard cab, ZR2, type. With 31' Bf Goodrich AT's. Its in near perfect condition no rust ect, ect. My problem begins when i when it takes a long time sometimes to start the motor, or when im at a stop and go light, or jsut in park, and it idles sometimes very rough. It has a new fuel pump, new fuel filter, new EGR valve, new cap and rotor, and plug wires all within the last couple months. I plugged it into the computer and there are no trouble codes of anykind. I have the 4.3L "W" model engine, supposedly high output or something, beats me. So i went to emmisions and it passed everything but the HC which means that there is too much fuel coming out the exhaust. I checked the fuel pressure when its running, im pushing just about 50 to 55psi of fuel pressure, and all the vacuum hoses seem to be fine too. The problem comes when the fuel pressure sames the same throughout the whole rpm range. I found that a little weird. Im getting ok gas milage, but i need to fix this problem soon, because it has to pass emissions, BTW, i live in Wisconsin. I'm leaning towards the fuel pressure regulator. If anyone has any suggestions or input id really appreciate it. Thanks! ALSO does anyone know what the normal fuel pressure shoudl be at idle, and at open throttle? thanks.

[jackass#1]

your fuel pressure should be between 54 and 62psi. 50 to 55 is low. this info is from haynes manual. the regulator keeps too much fuel from going to the injectors. it is to send exessive fuel to the return line.
youre suppose to do the pressure check with key to on possiyion without the engine running. ie you did it with engine on you might be good with 50 to 55. try to check it with engine oee and see what you get. if its still the same its not your regulator.

[Trucks!]

OK, well thats what it is when its just key on also do you have any other ideas?

[jackass#1]

if thats all the pressure you have something is wrong. that is what is causing rough idle, not enough pressure. and if you already changed filter than the pump is next.

[Trucks!]

Thanks for all yoru input, hopefully i can get it fixed.

[Fireplug]

Low fuel pressure will cause a drivabilty problem BUT it will NOT cause a failed emission test due to high HC. HC = unburnt fuel in the exhaust system.
Spark plugs, wires , cap and rotor, dripping or clogged injector , wrong timing will cause a high HC reading not low fuel pressure. If the low pressure was a problem he would be running lean not rich

[jackass#1]

he has a driving problem. i was trying to help with that. i never once said anything about it causing him to fail the test. it is causing the rough idle. many things that could cause or give faulty lean or rich readings.
try to help out and get thrown down for it. people here are really making this place unworthy of those just trying to help. im done with this sight.

[Fireplug]

JA
I did not mean to sound like I was Blasting you because I would not do that.
As a GM Master Tech with 15 years of service I have seen a lot of strange things happen with our Autos. The Failed emission problem is most likly the the outcome of the rough idle. A rough idle in most cases is a type of miss-fire (lean vacuum leak etc or rich dripping injector bad plugs etc.) He just might have more then 1 problem and low fuel pressure is a problem. I was just saying that low fuel pressure will not cause a high HC reading on the emission test.
I hope we are ok with each other

[jackass#1]

were cool. sorry for going on like that , bad day. took it all the wrong way, sorry. and youre right, emissions!
im a s10 AF addict, ill never stop.