Hard starting and rough idle

[mrl390]

Sometimes when I go to start my car it will take a few tries for it to start. Then it will idle rough until I drive it once, then the idle smooths out. It seems to do it the most when the car has been sitting. It will also blow some oil out the exhaust when I start it after it sits for more than a day or two. I think that is the valve seals leaking tho. It doesnt seem like Im losing any power because once it warms up, it has plenty of pep. Any ideas on what I should check? Its not much of a problem if I drive the car everyday, but I carpool up at school so the car sometimes sits for a few days.

[mrl390]

Could this be a fuel pressure regulator problem maybe? I just read a post on w-body.com about a guy that had almost the exact problem. Hard starting, rough idle and black smoke out the exhaust. Maybe I am mistaking black smoke for burning oil? I did notice a few times that it smelled real bad like gas for a few seconds after startup. I thought it was just flooded from not starting right away. Maybe I am getting black smoke and burning oil. My luck could just be that bad, lol.

[mrl390]

Thoughts anyone?

[Rhedalert]

Could be a case of getting a little bit too much fuel on startup. Start with the easy things: Clean your MAF sensor, idle control valve, and throttle plate. Then reset the PCM, let it relearn (~150 miles of driving) then see how it is.

Another option is if you have access to a scantool, check out the fuel trim readings and see if the PCM is "pulling" fuel.

[stoneymonk]

How do you reset the pcm and were is it located on a 95 lumina

[GTP091]

How do you reset the pcm and were is it located on a 95 lumina

unplug the battery and let it sit for a bit. The ECM/PCM should be on the paseenger side in front of the strut tower. Black rectangular box.

[robertisaar]

unplug the battery and let it sit for a bit. The ECM/PCM should be on the paseenger side in front of the strut tower. Black rectangular box.

black? if its a 3.4, then yes black, if not its a silver box with 3 plugs coming out of it, 1 black, 1 blue, and 1 clear.

[GTP091]

You won't need to touch the ECM to reset it anyway. Do a search on idle relearn in the threads of the DOHC section you will find the info there. I would suspect the fuel pressure regulator; your problem seems to be with the ca r running rich. wipe some of the black stuff off the exhaust tips it probably smells like gas. Does the car smoke black when doing this?? When was the last time the fuel filter was replaced?? and the PCV valve??

[mrl390]

I believe the PCV valve and fuel filter are original but the filter may have been replaced once. Im assuming the fuel pressure regulator is just under the black plastic engine cover. The thing that gets me is that the car only blows black smoke after it sits. Thats why I thought valve seals were the culprit. Ill try and clean the MAF this weekend but I dont think that is the problem. 43000 miles and that thing is spottless inside. What do you mean by throttle plate? Do you mean the butterfly in the throttle body? Ill check that out too. Im going to go ahead and just replace the FPR to be safe. Im tired of this thing not wanting to start. Thanks for the replies guys.

[mrl390]

I forgot to ask, how exactly do I replace the regulator. I cant tell if I can just replace the diaphram or the whole regulator needs replaced. I can see where the diaphram fits into the regulator, but there is a hard black "sealant" around it, almost like a solder. Also, do I need to depressurize the rails or do they depressurize when the car is shut off? Thanks

[walterdude]

I agree that it sounds like the FPR.... You need to make sure though... I don't know how the 95s are but, on a 93 it's buried under the plenum, (not too big of a job, just be aware of it), and they are not real cheap. Find out where the vac line for the FPR is, if there is gas or a strong gas smell in that line it means bad diaphragm in the FPR... Also a fuel pressure test is called for. There is a Schrader type valve for this... You SHOULD search!!! There are a few recent threads dealing with just this problem.... I've posted details on the tests you need to do... Also other members gave good input... Check it out!!!!
Actually here's a link that sounds like you but, a bit more extreme!!

http://60degreev6.com/forum/f100/95-3-4-dohc-flooding-like-noahs-ark-t41950

Do a search for more FPR threads...
It could be other things---do some tests to verify the culprit to possiby save time and $$$!!!
Good luck,,,
Tom...

[walterdude]

I agree that it sounds like the FPR.... You need to make sure though... I don't know how the 95s are but, on a 93 it's buried under the plenum, (not too big of a job, just be aware of it), and they are not real cheap. Find out where the vac line for the FPR is, if there is gas or a strong gas smell in that line it means bad diaphragm in the FPR... Also a fuel pressure test is called for. There is a Schrader type valve for this... You SHOULD search!!! There are a few recent threads dealing with just this problem.... I've posted details on the tests you need to do... Also other members gave good input... Check it out!!!!
Actually here's a link that sounds like you but, a bit more extreme!!

http://60degreev6.com/forum/f100/95-3-4-dohc-flooding-like-noahs-ark-t41950

Do a search for more FPR threads...
It could be other things---do some tests to verify the culprit to possiby save time and $$$!!!
Good luck,,,
Tom...

[mrl390]

I have a 97 not a 95. I think they are different. The regulator is actually right beside the engine cover, not under it. The vacuum line on it should go right to the throttle body, correct? I pulled that line at the regulator and no gas came out, no trace of gas, not even a smell of gas. I think next I am going to clean the IAC because when my car idles (all the time) it kind of hunts for an RPM. Only time it doesnt do it is if Im in drive with my foot on the brake.

[95SleeperAcheiva]

Funny that this should come up.
I got a '94 GP with the 3100.

Hard start, will fire if i prime the pump a few times, then crank.
I changed fuel pump and filter, I bought the car as a no run.
I too suspected an FPR, changed it, same thing.
Since my FPR was used, I changed it again, same thing.

I'm suspecting leaky injectors.

BTW, when I pulled the old pump out of the tank, the gas smelled funny, like thinner, and all the rubber pieces around the pump were like play dough. I never seen that before, oh and the car had been sitting for 3 years. No the gas wasn't just old, I know old gas smell, this was really funky!

[GTP091]

Have you tried any heavy top engine cleaner?? Might be worth a shot. seafoam is what guys on here recommend. To the best of my knowledge the valves don't have seals but rather seats; metal on metal and you can test them by doing a compression check. I wouldn't think bad seals won't cause black sooty exhaust.