| Non GMC... but still GM [message #213937] |
Wed, 10 July 2013 15:37  |
petemosss
Messages: 221
Registered: August 2008
Location: Jacksonville, Florida
Karma: 0
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94 Chevy c2500 V6 4.3L Auto 4sp.
Symptoms- stalls, hesitates off idle. If I let it idle out a few feet then apply throttle it's ok. Apply throttle from a dead stop and stalls instantly. Cold or Hot. Also has a periodic hesitation at any speed or rpm @ once a minute. Other than that runs great!
Cannot get codes via check engine light or obd 1 reader from computer but everything works
No apparent air leaks TBI wise
Head gaskets replaced w. good compression on all. Heads, Intake free of carbon
Timing dead on
All pertinent electrical connections checked and cleaned.
New- Cap, Rotor (MSD) plugs (AC Delco) Wires (Lifetime NAPA) EGR valve, EGR solenoid, all vacuum lines, air and fuel filter.
What next, I'm baffled!
Another ecm or hei dist. pick up?
Pete
74 Canyon Lands 26' "Emery"
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| Re: [GMCnet] Non GMC... but still GM [message #213939 is a reply to message #213937] |
Wed, 10 July 2013 15:42  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I'd look closely at the TPS.
--johnny
From: pete <petemossss@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Wednesday, July 10, 2013 4:37 PM
Subject: [GMCnet] Non GMC... but still GM
94 Chevy c2500 V6 4.3L Auto 4sp.
Symptoms- stalls, hesitates off idle. If I let it idle out a few feet then apply throttle it's ok. Apply throttle from a dead stop and stalls instantly. Cold or Hot. Also has a periodic hesitation at any speed or rpm @ once a minute. Other than that runs great!
Cannot get codes via check engine light or obd 1 reader from computer but everything works
No apparent air leaks TBI wise
Head gaskets replaced w. good compression on all. Heads, Intake free of carbon
Timing dead on
All pertinent electrical connections checked and cleaned.
New- Cap, Rotor (MSD) plugs (AC Delco) Wires (Lifetime NAPA) EGR valve, EGR solenoid, all vacuum lines, air and fuel filter.
What next, I'm baffled!
Another ecm or hei dist. pick up?
--
Pete
74 Canyon Lands 26' "Emery"
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Non GMC... but still GM [message #213943 is a reply to message #213937] |
Wed, 10 July 2013 15:56 |
chasingsummer
Messages: 434
Registered: May 2011
Location: asheboro, nc
Karma: 0
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if this was my old porsche with primative fuel injection then i would think i had an injector that was clogged, but that was before there were oxygen sensor. I assume they add to the mix, but not sure how.
if it was on my harley, i would wonder if carb float had and issue.
is there a tps (throttle position sensor), i am still thinking old porsche. being dirty on its contacts i would expect it to do similiar.
sounds to me like something is dirty
keep in mind my knowledge may be equal to the man who has no clue. if it was my car, i would put either sea foam or mmo in gas in a slightly heavy concentration and hope issue went away.
i would also list here and hope to hear from some others , because i agree with you that this forum has many brilliant people on it.
brian
asheboro, nc
75 eleganza, 74 build
119k miles and counting,
DOG HOUSE
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| Re: Non GMC... but still GM [message #213944 is a reply to message #213937] |
Wed, 10 July 2013 15:56 |
petemosss
Messages: 221
Registered: August 2008
Location: Jacksonville, Florida
Karma: 0
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Johnny, just bought truck. It looks like there is a nice shiney tps in there replaced by po. Will look into.
Steve, it shifts very smoothly from 1st to second @ 15-18 mph.
Pete
74 Canyon Lands 26' "Emery"
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| Re: [GMCnet] Non GMC... but still GM [message #213949 is a reply to message #213937] |
Wed, 10 July 2013 16:39 |
storm'n
Messages: 492
Registered: April 2007
Location: Ont. Can
Karma: 0
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Sounds like a flat spot just off idle in the TPS [throttle position switch]. My 93 5.7 did the same thing. It can be checked with an ohm meter. Easy to change if it's similar to a 5.7.
Norm
From: pete <petemossss@gmail.com>
>To: gmclist@temp.gmcnet.org
>Sent: Wednesday, July 10, 2013 4:37:52 PM
>Subject: [GMCnet] Non GMC... but still GM
>
>
>
>
>94 Chevy c2500 V6 4.3L Auto 4sp.
>
>Symptoms- stalls, hesitates off idle. If I let it idle out a few feet then apply throttle it's ok. Apply throttle from a dead stop and stalls instantly. Cold or Hot. Also has a periodic hesitation at any speed or rpm @ once a minute. Other than that runs great!
>
>Cannot get codes via check engine light or obd 1 reader from computer but everything works
>
>No apparent air leaks TBI wise
>
>Head gaskets replaced w. good compression on all. Heads, Intake free of carbon
>
>Timing dead on
>
>All pertinent electrical connections checked and cleaned.
>
>New- Cap, Rotor (MSD) plugs (AC Delco) Wires (Lifetime NAPA) EGR valve, EGR solenoid, all vacuum lines, air and fuel filter.
>
>What next, I'm baffled!
>
>Another ecm or hei dist. pick up?
>--
>Pete
>74 Canyon Lands 26' "Emery"
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
>
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| Re: Non GMC... but still GM [message #213971 is a reply to message #213937] |
Wed, 10 July 2013 20:57 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Check fuel pressure to rule that out. They took the TPS right out of my mouth. Dead spot on the pot is possible. Also initial setting could be out of range. i know on a Regal LC2 it's .45V at idle and about 4.5 at WOT. Might be same for Chevy. Back probe or use scan tool to read. Also reset base idle air rate. if that is off you can get tip in sag. Remove inspect and replace all your ign wires. My Tahoe HEI vaporized the main lead from the coil to the cap. Ran funny and then totally died. Also on Chevys I've found corrosion on the coil tower and on the 12V feed side. Also, hard plastic vac lines can look good and be cracked. Is the EGR working ok. Early 4.3 Vortecs had big problems with carbon chips shedding and sticking in the EGR pintle. Ask me how I know !
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Non GMC... but still GM [message #213982 is a reply to message #213937] |
Wed, 10 July 2013 22:08 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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My experience with performance problems and no codes on GM 4.3s:
1. Carbon stuck in the EGR valve. Remove it clean in and replace the gasket with one with a built in screen. I have replaced 2.
2. Fuel regulator leaking part of the spider fuel distribution system remove the top intake cover to see it and replace it. I have replaced 2
3. Bad / weak fuel pump. Check it with a fuel pressure tester. Minimum 55 PSI, normal range is up to about 70 PSI. I have replaced 5. I carry a spare fuel pump in both of our Blazers.
4. MAF sensor. Get one from AZ and if it doesn't fix it, just return it. 5 minute install and around $110 (exchange.) I have replaced 3.
5. TPS I have replaced 1
The above replacement numbers are across 4 GM vehicles with year of manufacture between 1991 and 1999 and about 700,000 miles
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Non GMC... but still GM [message #214007 is a reply to message #213940] |
Thu, 11 July 2013 06:08 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I may have misunderstood the symptom(s). I thought the engine was stumbling off idle.
--johnny
________________________________
From: Steve Weinstock <steve.weinstock@cox.net>
To: gmclist@temp.gmcnet.org
Sent: Wednesday, July 10, 2013 4:47 PM
Subject: Re: [GMCnet] Non GMC... but still GM
I have a very very similar issue with my GMC Motorhome.
I haven't chased it down yet - but folks have suggested that my torque converter is shot. Seems to be a bit better when at operating temps...
As I was asked - are you sure that you're starting out in 1st gear ?
Good luck to both of us.
Steve W
1973 23'
Southern California
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Non GMC... but still GM [message #214009 is a reply to message #213944] |
Thu, 11 July 2013 06:17 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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If there is slack in the linkage (throttle butterfly opens before the TPS moves) you'd get a 'stumble' much like a malfunctioning accelersator pump on a carbureted engine. However, a new TPS makes you think that potential problem has been addressed, and you might need to look elsewhere. Or at least the PO also had the problem and was trying to correct it.
For a quick n dirty, take an analog ohmmeter and connect it to two of the pins on the TPS connector, engine and ignition off. As you open the throttle linkage by hand, the resistance should begin to change as soon as the throttle moves, and it should change smoothly - no interruptions - throughout the range of the throttle, no jerks or dropouts.
--johnny
________________________________
From: pete <petemossss@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Wednesday, July 10, 2013 4:56 PM
Subject: Re: [GMCnet] Non GMC... but still GM
Johnny, just bought truck. It looks like there is a nice shiney tps in there replaced by po. Will look into.
Steve, it shifts very smoothly from 1st to second @ 15-18 mph.
--
Pete
74 Canyon Lands 26' "Emery"
_______________________________________________
GMCnet mailing list
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http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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