Truck won't idle! help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BossHogg69 · 04-24-2009, 06:52 PM

My truck started idling like pooh yesterday, the brake booster is messed up (have one on order) and I can hear it sucking air inside the cab. The booster has been acting up since monday, but the truck really started running crappy yesterday. Is the booster not letting the motor idle correctly, or am I off base here? I recently put a cap and rotor in the distributor and everything has been fine. Thanks in advance for any help.

**Boog** · 04-24-2009, 08:07 PM

Yessir. When the booster diaphram goes bad it allows the engine to loose vacumn and run rough. You will hear it sucking down by the brake pedal.

BossHogg69 · 04-24-2009, 08:10 PM

Thanks Boog, you're just right up the rode from me!

PanelDeland · 04-24-2009, 09:16 PM

Don't run it much with the massive vacuum leak.It will cause a lean condition and may break your engine and bank,in that order.I think LHM has had this problem before.

BossHogg69 · 04-24-2009, 11:33 PM

Well, i plugged off the vaccuum line to the brake booster and guess what... She still wouldn't idle. So, i took off the air cleaner, put my hand over the choke horn and she idled up, nice and smooth, which means, I still had a vaccuum leak somewhere. Turns out, the vaccuum line from the intake going to what used to be the modulator valve on the TH400 wasn't removed and plugged off when the Tremec 5 speed was swapped in. Duh....

**Boog** · 04-25-2009, 06:31 PM

Well that'll sure do it. Glad you found it.

04-24-2009, 06:52 PM	#1
BossHogg69 motor exploder Join Date: Mar 2009 Location: Pittsburgh, PA Posts: 2,346	Truck won't idle! help! My truck started idling like pooh yesterday, the brake booster is messed up (have one on order) and I can hear it sucking air inside the cab. The booster has been acting up since monday, but the truck really started running crappy yesterday. Is the booster not letting the motor idle correctly, or am I off base here? I recently put a cap and rotor in the distributor and everything has been fine. Thanks in advance for any help. __________________ Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac Use the SEARCH function on this forum - it is your friend!!

04-24-2009, 08:07 PM	#2
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,459	Re: Truck won't idle! help! Yessir. When the booster diaphram goes bad it allows the engine to loose vacumn and run rough. You will hear it sucking down by the brake pedal. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

04-24-2009, 08:10 PM	#3
BossHogg69 motor exploder Join Date: Mar 2009 Location: Pittsburgh, PA Posts: 2,346	Re: Truck won't idle! help! Thanks Boog, you're just right up the rode from me! __________________ Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac Use the SEARCH function on this forum - it is your friend!!

04-24-2009, 09:16 PM	#4
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Truck won't idle! help! Don't run it much with the massive vacuum leak.It will cause a lean condition and may break your engine and bank,in that order.I think LHM has had this problem before. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

04-24-2009, 11:33 PM	#5
BossHogg69 motor exploder Join Date: Mar 2009 Location: Pittsburgh, PA Posts: 2,346	Re: Truck won't idle! help! Well, i plugged off the vaccuum line to the brake booster and guess what... She still wouldn't idle. So, i took off the air cleaner, put my hand over the choke horn and she idled up, nice and smooth, which means, I still had a vaccuum leak somewhere. Turns out, the vaccuum line from the intake going to what used to be the modulator valve on the TH400 wasn't removed and plugged off when the Tremec 5 speed was swapped in. Duh.... __________________ Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac Use the SEARCH function on this forum - it is your friend!!

04-25-2009, 06:31 PM	#6
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,459	Re: Truck won't idle! help! Well that'll sure do it. Glad you found it. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross



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