Rough idle - wants to die - only on hills? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Gibson · 08-14-2009, 05:15 PM

My '78 Silverado just got back from the tranny shop (rebuild and shift kit) and I noticed it was acting up on the way there (running rough and sputtering a bit). So I had them check the timing and give it a tune up. They said it had been way retarded, and advanced it to smooth it out @2500 RPM.

Nice guys, and I trust them. I'm sure it was running great there at the shop. But on the way home, I went up a hill and it started acting up again. My driveway is a hill as well, and when I let it idle in the driveway it starts to get really rough and want to die.

I have not tested it again on level ground in case this was a sign of something more severe.

Could this be fuel pump? Or am I imagining the hill thing and this sound like timing? Is there anything that would make it run this way that you guys can think of?

So frustrating! All I'm wanting to do is

**old Rusty C10** · 08-14-2009, 06:27 PM

junk in the tank or the fuel filter? I have a clear one on mine before the carb just to make sure

Gibson · 08-14-2009, 06:28 PM

Hmm... Tank could be a possibility - the filter is brand new though. It doesn't look gunked up at all yet.

**old Rusty C10** · 08-14-2009, 06:35 PM

then its a goof possibility there is junk in the tank...If you try to get on it on the hill do you get backfire or pre ignition>?

Gibson · 08-14-2009, 06:41 PM

If I gas it, it starts to act REALLY rough. Shakes a whole lot. But it doesn't really sound like it is knocking.

**old Rusty C10** · 08-14-2009, 10:16 PM

thats fuel related then

karl · 08-15-2009, 03:10 PM

Sounds like fuel problem

Dave Kay · 08-15-2009, 05:30 PM

Have you checked for vacuum leak? Since the trans install maybe the vac line from intake manifold to trans came loose?

Good luck

Gibson · 08-15-2009, 08:43 PM

I checked the vacuum line, and it was still hooked up. Also it was doing the same thing right before I went in.

But I think it is fixed now! I replaced the cheap in line filter (which was new, but on the small side) with a larger canister type. I also replaced the fuel pump, which needed to be done anyway.

Started it up - and it sounds way way better. Once or twice maybe in my 30 minute test drive it might of hesitated a little bit - but that could have been my sticky pedal. I took it out on all the hills that were giving me issues and it did great!

Thanks everyone! It WAS a fuel problem. Whew! Glad I didn't have to mess with the carb....

08-14-2009, 05:15 PM	#1
Gibson Registered User Join Date: Jul 2009 Location: Maryville, TN Posts: 132	Rough idle - wants to die - only on hills? My '78 Silverado just got back from the tranny shop (rebuild and shift kit) and I noticed it was acting up on the way there (running rough and sputtering a bit). So I had them check the timing and give it a tune up. They said it had been way retarded, and advanced it to smooth it out @2500 RPM. Nice guys, and I trust them. I'm sure it was running great there at the shop. But on the way home, I went up a hill and it started acting up again. My driveway is a hill as well, and when I let it idle in the driveway it starts to get really rough and want to die. I have not tested it again on level ground in case this was a sign of something more severe. Could this be fuel pump? Or am I imagining the hill thing and this sound like timing? Is there anything that would make it run this way that you guys can think of? So frustrating! All I'm wanting to do is

08-14-2009, 06:27 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,297	Re: Rough idle - wants to die - only on hills? junk in the tank or the fuel filter? I have a clear one on mine before the carb just to make sure __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

08-14-2009, 06:28 PM	#3
Gibson Registered User Join Date: Jul 2009 Location: Maryville, TN Posts: 132	Re: Rough idle - wants to die - only on hills? Hmm... Tank could be a possibility - the filter is brand new though. It doesn't look gunked up at all yet.

08-14-2009, 06:35 PM	#4
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,297	Re: Rough idle - wants to die - only on hills? then its a goof possibility there is junk in the tank...If you try to get on it on the hill do you get backfire or pre ignition>? __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

08-14-2009, 06:41 PM	#5
Gibson Registered User Join Date: Jul 2009 Location: Maryville, TN Posts: 132	Re: Rough idle - wants to die - only on hills? If I gas it, it starts to act REALLY rough. Shakes a whole lot. But it doesn't really sound like it is knocking.

08-14-2009, 10:16 PM	#6
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,297	Re: Rough idle - wants to die - only on hills? thats fuel related then __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

08-15-2009, 03:10 PM	#7
karl Registered User Join Date: Dec 2004 Location: grand terrace , caifornia Posts: 338	Re: Rough idle - wants to die - only on hills? Sounds like fuel problem

08-15-2009, 05:30 PM	#8
Dave Kay Registered User Join Date: Dec 2006 Location: Victorville, CA Posts: 68	Re: Rough idle - wants to die - only on hills? Have you checked for vacuum leak? Since the trans install maybe the vac line from intake manifold to trans came loose? Good luck __________________

08-15-2009, 08:43 PM	#9
Gibson Registered User Join Date: Jul 2009 Location: Maryville, TN Posts: 132	Re: Rough idle - wants to die - only on hills? I checked the vacuum line, and it was still hooked up. Also it was doing the same thing right before I went in. But I think it is fixed now! I replaced the cheap in line filter (which was new, but on the small side) with a larger canister type. I also replaced the fuel pump, which needed to be done anyway. Started it up - and it sounds way way better. Once or twice maybe in my 30 minute test drive it might of hesitated a little bit - but that could have been my sticky pedal. I took it out on all the hills that were giving me issues and it did great! Thanks everyone! It WAS a fuel problem. Whew! Glad I didn't have to mess with the carb....



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