L6 250 Bogs When Starting from Stop - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bluec10 · 08-27-2009, 04:07 PM

My saga continues. I just finished installing a new air cleaner and power brake booster. The brakes seem to be working fine, but after I installed all this stuff the performance of the truck took a hit. Before I started working on it the engine was as smooth as could be - very easy to start and very smooth acceleration from stop to highway speed. Now when I step on the gas it bogs and I have to rev it way up to get it to keep from stalling when I start from a stop. I put in a new fuel filter a month ago. The air filter is new. All the vacuum lines are new. New points, condenser, rotor, cap, and plug wires.

What should I look at first?

mclairmo · 08-27-2009, 04:11 PM

Usually, the culprit is whatever you last installed. Try pluggin the brake booster vacuum line where you have taken it off the carb or intake and see if that cures it. if it does, then maybe the booster diaphram is bad and is causing a vacuum leak? Also, did you set the dwell properly on the new points? Is the condesor good? I had one not hooked up properly (wire jiggled loose) and acted like your truck. Are all the plug wires at the correct location and nice and tight? Double check everything you did to find the problem.

69GMCLonghorn · 08-27-2009, 04:48 PM

yeah what he said... Check the last thing you did. It sounds like a classic sign of running lean, which means it's probably due to the brake booster situation.

cdowns · 08-27-2009, 05:14 PM

did you set the timing after changing the points?// did you set points with a dwell gauge or just a feeler gauge?

mclairmo · 08-27-2009, 05:17 PM

Quote:

Originally Posted by cdowns

did you set the timing after changing the points?// did you set points with a dwell gauge or just a feeler gauge?

I always use my little analog dwell meter as it is much more accurate than feeler gauges. Also, a good digital multimeter should have a dwell function.

bluec10 · 08-27-2009, 05:21 PM

A leaky booster is a possibility. I didn't use a dwell meter but a feeler gauge. But, the fact that the truck was running perfectly after I put in the new ignition parts should indicate that it is set right. I'm going to plug the booster line and see if that is the problem.

mclairmo · 08-27-2009, 05:33 PM

If the truck started to run like crap only after the booster install, then that must be the culprit. You can get a rebuilt booster from Autozone for $100. Not sure if you have Autozone up in Canada. Don't you have socialized auto repair up there? The government should subsidize that repair, right? J/K. I have an aunt that lives in Edmonton Alberta and I've been there once. Beautiful place and really nice folks.

08-27-2009, 04:07 PM	#1
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	L6 250 Bogs When Starting from Stop My saga continues. I just finished installing a new air cleaner and power brake booster. The brakes seem to be working fine, but after I installed all this stuff the performance of the truck took a hit. Before I started working on it the engine was as smooth as could be - very easy to start and very smooth acceleration from stop to highway speed. Now when I step on the gas it bogs and I have to rev it way up to get it to keep from stalling when I start from a stop. I put in a new fuel filter a month ago. The air filter is new. All the vacuum lines are new. New points, condenser, rotor, cap, and plug wires. What should I look at first? __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.

08-27-2009, 04:11 PM	#2
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: L6 250 Bogs When Starting from Stop Usually, the culprit is whatever you last installed. Try pluggin the brake booster vacuum line where you have taken it off the carb or intake and see if that cures it. if it does, then maybe the booster diaphram is bad and is causing a vacuum leak? Also, did you set the dwell properly on the new points? Is the condesor good? I had one not hooked up properly (wire jiggled loose) and acted like your truck. Are all the plug wires at the correct location and nice and tight? Double check everything you did to find the problem.

08-27-2009, 04:48 PM	#3
69GMCLonghorn Registered User Join Date: Dec 2006 Location: Porter Ranch, CA Posts: 978	Re: L6 250 Bogs When Starting from Stop yeah what he said... Check the last thing you did. It sounds like a classic sign of running lean, which means it's probably due to the brake booster situation.

08-27-2009, 05:14 PM	#4
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: L6 250 Bogs When Starting from Stop did you set the timing after changing the points?// did you set points with a dwell gauge or just a feeler gauge? __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY Last edited by cdowns; 08-27-2009 at 05:15 PM.

08-27-2009, 05:21 PM	#6
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	Re: L6 250 Bogs When Starting from Stop A leaky booster is a possibility. I didn't use a dwell meter but a feeler gauge. But, the fact that the truck was running perfectly after I put in the new ignition parts should indicate that it is set right. I'm going to plug the booster line and see if that is the problem. __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.

08-27-2009, 05:33 PM	#7
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: L6 250 Bogs When Starting from Stop If the truck started to run like crap only after the booster install, then that must be the culprit. You can get a rebuilt booster from Autozone for $100. Not sure if you have Autozone up in Canada. Don't you have socialized auto repair up there? The government should subsidize that repair, right? J/K. I have an aunt that lives in Edmonton Alberta and I've been there once. Beautiful place and really nice folks. Last edited by mclairmo; 08-27-2009 at 05:33 PM.

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