bad stumbling/stalling

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bad stumbling/stalling - 6/24/2008 3:20:17 PM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline This problem as not much of a problem during the winter, but was still apparent. It only occured after a TB rebuild. 2.8 86 S10. Tune up about 2k miles old. Ill be driving down the road, and all of a sudden the gas pedal loses ALL effectiveness and it idles at about 10 RPM before it dies. Yes, TEN. Just enough to keep running. If i floor it while it does this, i get the throaty wide open sound but not nearly as loud as it should be, and it continues to slow down, even while its in gear. If i shut off the motor or let it die, then crank it again, it will run normally until a few minutes later and it repeats. Three things im guessing. 1. The fuel pump. When i replaced the filter about four months ago, i had a small amount of black carbon in it. I didnt think anything of it. 2. Some kind of engine cut-off related to oil pressure that kicks in after a few of the closed cycle loops? I just got to my girlfriends house and this happened about ten times. I wa at normal temps the whole time, good voltage, only the oil pressure was a bit low. (possibly due to high ambient temps and the normal temp of the engine. 3. TPS/IAC WAYYY out of adjustment? Sorry i typed so much, i just wanted to give as much info as possible. This is my only means of transportation and its not like i beat this truck up by any means. Help please? _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... Post #: 1

RE: bad stumbling/stalling - 6/26/2008 7:55:25 AM    Sunshine Coaster Posts: 65 Joined: 9/22/2007 From: Sunshine Coast, B.C. Canada Status: offline Sounds like a fuel delivery problem to me..is it the original fuel pump or have you replaced it? Ideally if you could tee into your fuel line to the TB with a pressure gauge you could monitor the pressure. Has it thrown any codes?...if it was the IAC or another sensor there should be a code in there. You say it started to happened right after the TB rebuild..did you do anything to the injectors other than change the screens? Did you tear it right down to the base plate and change that big thick gasket? Any chance it''s sucking air from anywhere? While it''s running with the air cleaner off take a propane bottle and open the nozzle just a tad...minimum flow, and run it around the base gasket, if the engine speeds up you''ve got a leak.  Good luck. _____________________________ 1986 Blazer 4x4...2.8 liter 4 speed. 63k original miles 2001 Neon R/T..210 HP. with mods 1978 Chevy 1/2T truck..380 HP. 350...almost an antique (in reply to 86S10) Post #: 2

RE: bad stumbling/stalling - 6/26/2008 3:38:28 PM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline No codes, i pride myself on having a CEL-free truck. Original fuel pump as far as i know. I stripped the TB all the way down and replaced all the gaskets and screens, but didnt change anything. I cant get to a propane torch but will a butane cigarette lighter thats been adjusted to the max work? Ill get a pressure gauge from advance or something and post it up. < Message edited by 86S10 -- 6/26/2008 3:48:03 PM > _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... (in reply to Sunshine Coaster) Post #: 3

RE: bad stumbling/stalling - 6/27/2008 8:19:21 PM    DC_X   Posts: 3 Joined: 6/14/2008 Status: offline Sounds exactly like when my MAP sensor failed this winter, oil pressure dropped very low. Disconnecting the MAP while the engine is idling should give you a similar experience. I could get about 10-15 miles away just fine, but anywhere after that and it would just lose all power, had to floor it to maintain speed on the highway, then it''d come back for another 5-10 miles. Each cutout lost all oil pressure. (in reply to 86S10) Post #: 4

RE: bad stumbling/stalling - 6/29/2008 4:43:37 PM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline I havent had a single problem out of it since then, except for what feels like a low idle occasionally. I ran it up to the very top of second today with no hesitation, so im wondering what else it could be. Air filter is good, spray pattern in the TB is picture perfect. However, it does seem like i have about an eighth inch of pedal travel on the accelerator before any difference in idle speed is apparent. One time, i had it in first and was taking off, and it seemed like the engine was charging up or something. Its the only was i know how to explain it. I had the clutch out, was on the gas about a fifth of the way down with nothing happening. Then it just took off like i had brought the revs up but it was at a steady RPM. This only happened once. _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... (in reply to DC_X) Post #: 5

RE: bad stumbling/stalling - 6/30/2008 6:08:06 PM    BobbyC.   Posts: 5 Joined: 6/30/2008 Status: offline did this fix it? (in reply to 86S10) Post #: 6

RE: bad stumbling/stalling - 9/21/2008 1:46:12 PM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline fuel pressure is fine, cleaned the egr valve and replaced the gasket, checked the gap on all the plugs and replaced the pcv valve. It runs amazingly, it just wont idle right and EVERYTIME i take off in first it bucks and hesitates unless i launch from like 3k rpm. i either look like an idiot in traffic or im burning up the clutch. A buddy of mine said distributor, and i need a second opinion from you guys. *EDIT* I just checked the ohms on the TPS...it works up until about one eighth of the travel and then goes back to baseline. < Message edited by 86S10 -- 9/21/2008 3:25:20 PM > _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... (in reply to BobbyC.) Post #: 7

RE: bad stumbling/stalling - 9/22/2008 2:05:12 PM    dlboyd   Posts: 10 Joined: 9/22/2008 Status: offline had the same problem took a hammer and pounded on the catalytic converter all is fine now (in reply to 86S10) Post #: 8

RE: bad stumbling/stalling - 9/28/2008 7:03:26 PM    dlboyd   Posts: 10 Joined: 9/22/2008 Status: offline spoke to soon, still have problem (in reply to dlboyd) Post #: 9

RE: bad stumbling/stalling - 9/30/2008 6:26:51 PM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline im about to get out here and change the TPS. I shall update with results sometime tomorrow. _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... (in reply to dlboyd) Post #: 10

RE: bad stumbling/stalling - 10/1/2008 9:47:29 AM    86S10 Posts: 60 Joined: 12/8/2007 Status: offline So i got the part in, and i installed it so that its as low as possible at idle. Its now throwing code 22 (low signal voltage) at idle, but when i drive it around it disappears. Im gonna get to a multimeter sometime soon and get the volts right. btw, this made me laugh. If i tap the gas to about 1/3 travel very quickly while decelerating in gear, it tries to drive itself. _____________________________ *1986 S10 Blazer 2.8 TBI* Taymacjack: No i would rather just blame bush...its easier and requires less thought... (in reply to 86S10) Post #: 11

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