Home » Public Forums » GMCnet » Stranded at Repair Shop (Carb backfiring, stalling, and loss of power)
| Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102193] |
Thu, 07 October 2010 22:50  |
harborgal
Messages: 19
Registered: October 2010
Location: Winthrop Harbor, IL (NE I...
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We have a 77 GMC Motorhome Palm Beach with an Oldsmobile Toronado 455 engine that was just mechanically restored after being in slumber for 13 years. As part of the mechanical restoraion they rebuilt carburetor, distributor, and fuel pump along with a long laundry list of items. On the way from bringing her back from restoration she stalled about 4 times. Once when accelerating on to the highway when warm, once when warm backing into a parking space (stalled and couldn't get her started for 15 mins), and a few times when idling or driving at slower speeds.
We took her to a local mechanic who did the following...
"roadtested vehicle, hesitates upon acceleration, and back fires out carb at times. Checked timing, checked distributor, checked for vacuum leak, cheched PCV, checked vacuum hose routing, checked idle. Advanced timing 4 degrees, roadtested, ran better, but still not completely correct. May have carburator problem, is lacking fuel. Reset timing, 2 degrees advanced. These changes were made from the ignition system specifications."
After we got her back she seemed better (didn't stall and the exhaust was not as loud), however after about 3 hours of driving without issue she started losing power on slight inclines. We were trying to go 55, but she was barely holding 30. You can hear the engine struggling. These got worse and worse over the course of another hour. She got slower to the point she was not almost making small hills, was stalling, and back firing out of the carburetor along with not holding a constent speed with cruise control.
Please help! We have been camping at the repair shop for 5 days now. They have set the timings back to GMC specs and switched out the fuel pump, and checked the fuel filter. None of these has helped. We have another rebuilt carburetor on the way, but are not sure if that will solve the issue. Your expertise is much appreciated.
[Updated on: Thu, 07 October 2010 22:52] Report message to a moderator |
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| Re: Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102206 is a reply to message #102193] |
Thu, 07 October 2010 23:31  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Well, I wish I knew where you are currently located. This would help in trying to guess if you have a fuel heating (vapor lock) problem. It also might tell us if you got ethanol fuel on your last fill up.
There are many things that could cause this problem. You need to first determine if this is a fuel delivery or an ignition problem.
Then next time it fails and dies, open the hatch and remove the air cleaner. WITHOUT CRANKING the engine, look down the throat of the carburetor and depress the gas pedal all the way to the floor several times. You should see gas squirt into the barrels of the carb on the first and second depression of the pedal. If there is no squirting gas you have run out of gas in the carb and you have a fuel delivery problem. If there is gas then start looking at the ignition system.
A fuel delivery problem could be many things. Here a few that come to mind.
1. Carb filter in backwards.
2. Fuel heating causing vapor lock
3. fuel boiling in the tanks.
4. plugged filters or plugged socks inside the tanks
5. bad fuel lines.
6. electric fuel pump installed without a bypass check valve and the electric fuel pump not turned on or not running
7. bad fuel lines.
8. Vacuum in the tanks caused by a sealed gas cap and the fuel 9. Tank vent system not working
On the ignition side any of these could be failing when they get hot.
1. Failing coil
2. Stuck vacuum advance
3. Stuck vacuum advance
4. Bad ignition module (inside the distributor)
5. Bad pickup coil (inside the distributor)
If you are getting a replacement distributor or carburetor, DO NOT go to the auto parts store. The GMC motorhome distributor and carb are unique to the GMC. Go to Dick Paterson (Springfield Ignition), or Jim Kanomata (Applied GMC), or Jim Bounds (GMC COOP)
Definitely do not return your old core to any but the above 3. The GMC MH core is unique and getting a rebuilt carb without the speciific GMC core is impossible.
Please tell us where you are and maybe someone close by on the Black List can assist you.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102227 is a reply to message #102209] |
Fri, 08 October 2010 07:51 |
robert caudle
Messages: 25
Registered: January 2004
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had similar problem that turned out to be distributor\coil
mechanic in azizona found cracked coil.
another time lost a spring in the distributor, could run slowly up to about
45 and the started spitting and sputtering with occasional backfire....Jim
Bounds discovered problem and fixed.
----- Original Message -----
From: "Heather Taft" <taftheather@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, October 07, 2010 11:49 PM
Subject: Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling,and
loss of power)
>
>
> Thanks so much for the information! I really appreciate it. We are by no
> means experts so we have to rely on a knowledgable mechanic. Currently
> located in Wausaw, WI and were on our way around Lake Michigian back to
> the individuals who originally did the restoration. We have reached out
> to a few individuals on the black list, but I don't think there is anyone
> nearby with the mechanical expertise. The repair shop we are at doesn't
> seem to have the tools to do all the necessary tests so we are pretty much
> shooting into the wind.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102228 is a reply to message #102227] |
Fri, 08 October 2010 07:58 |
chip
Messages: 37
Registered: November 2009
Karma: -2
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Good Morning:
I chased a similar problem with my GMC. Replaced the cap, rotor, coil,
wires, module, fuel pump, all filters, adjusted timing, and it would still
come back... sometimes worse than others - but was always there. Turned out
I had a crack in the intake manifold under the carburetor .... when the
engine warmed up the crack opened up ... and totally threw off the air/fuel
mixture.
Chip
On Fri, Oct 8, 2010 at 7:51 AM, rl caudle <rlcaudle@charter.net> wrote:
> had similar problem that turned out to be distributor\coil
> mechanic in azizona found cracked coil.
>
>
> another time lost a spring in the distributor, could run slowly up to about
> 45 and the started spitting and sputtering with occasional backfire....Jim
> Bounds discovered problem and fixed.
> ----- Original Message -----
> From: "Heather Taft" <taftheather@hotmail.com>
> To: <gmclist@temp.gmcnet.org>
> Sent: Thursday, October 07, 2010 11:49 PM
> Subject: Re: [GMCnet] Stranded at Repair Shop (Carb backfiring,
> stalling,and
> loss of power)
>
>
> >
> >
> > Thanks so much for the information! I really appreciate it. We are by no
> > means experts so we have to rely on a knowledgable mechanic. Currently
> > located in Wausaw, WI and were on our way around Lake Michigian back to
> > the individuals who originally did the restoration. We have reached out
> > to a few individuals on the black list, but I don't think there is anyone
> > nearby with the mechanical expertise. The repair shop we are at doesn't
> > seem to have the tools to do all the necessary tests so we are pretty
> much
> > shooting into the wind.
> > _______________________________________________
> > GMCnet mailing list
> > List Information and Subscription Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
>
> --------------------------------------------------------------------------------
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.862 / Virus Database: 271.1.1/3183 - Release Date: 10/07/10
> 13:34:00
>
> _______________________________________________
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and lose of power) [message #102234 is a reply to message #102193] |
Fri, 08 October 2010 08:34 |
Carleton Douglas[1]
Messages: 174
Registered: March 2006
Karma: 0
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Senior Member |
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WHERE ARE YOU?
On Thu, Oct 7, 2010 at 8:50 PM, Heather Taft <taftheather@hotmail.com> wrote:
>
>
> We have a 77 GMC Motorhome Palm Beach with an Oldsmobile Toronado 455 engine that was just mechanically restored after being in slumber for 13 years. As part of the mechanical restoraion they rebuilt carburetor, distributor, and fuel pump along with a long laundry list of items. On the way from bringing her back from restoration she stalled about 4 times. Once when accelerating on to the highway when warm, once when warm backing into a parking space (stalled and couldn't get her started for 15 mins), and a few times when idling or driving at slower speeds.
>
> We took her to a local mechanic who did the following...
>
> "roadtested vehicle, hesitates upon acceleration, and back fires out carb at times. Checked timing, checked distributor, checked for vacuum leak, cheched PCV, checked vacuum hose routing, checked idle. Advanced timing 4 degrees, roadtested, ran better, but still not completely correct. May have carburator problem, is lacking fuel. Reset timing, 2 degrees advanced. These changes were made from the ignition system specifications."
>
> After we got her back she seemed better (didn't stall and the exhaust was not as loud), however after about 3 hours of driving without issue she started losing power on slight inclines. We were trying to go 55, but she was barely holding 30. You can hear the engine struggling. These got worse and worse over the course of another hour. She got slower to the point she was not almost making small hills, was stalling, and back firing out of the carburetor along with not holding a constent speed with cruise control.
>
> Please help! We have been camping at the repair shop for 5 days now. They have set the timings back to GMC specs and switched out the fuel pump, and checked the fuel filter. None of these has helped. We have another rebuilt carburetor on the way, but are not sure if that will solve the issue. Your expertise is much appreciated.
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Carleton Douglas
73 custom, by myself
Prescott, AZ
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and lose of power) [message #102244 is a reply to message #102234] |
Fri, 08 October 2010 10:08 |
harborgal
Messages: 19
Registered: October 2010
Location: Winthrop Harbor, IL (NE I...
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Some additional information. We are currently in Wausau, WI at the Chevy dealership because we were not sure where else to go and were towed in.
- Our last fill up was with most likely with a gas that contained that contains up to 10% ethanel
- The carb filter has been looked at and doesn't appear to be in backwards or wet from water.
- We have now had two mechanics look at it and they are saying the problem is fuel starvation.
- We were having issues with her stalling in 60 - 70 degree tempatures so not sure that vapor lock is our problem. She is stalling almost constantly at this time when starting up cold and at idle along with stalling when hot.
- We only have a mechanical fuel pump which was just swapped out and that is not the issue. Have looked at the fuel filters and that doesn't appear to be it either.
- We just under went a complete mechanical restoration so more of all the mechanicals are new or rebuilt (rebuilt engine, rebuilt carb, fuel pump, rebuilt distributor, cleaned out gas tanks, etc.)
Another GMC owner last night stopped by when they saw us next to the Walmart and gave us the name of someone locally who works on this type of engine and carb. Waiting for the new carb to arrive today before next plan of action.
[Updated on: Sat, 09 October 2010 12:38] Report message to a moderator |
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and lose of power) [message #102245 is a reply to message #102244] |
Fri, 08 October 2010 10:20 |
chip
Messages: 37
Registered: November 2009
Karma: -2
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Member |
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Heather:
Hoping you saw my e-mail from earlier. When they have the carburetor off
have them look at the intake manifold and see if they can see a crack in the
secondaries .... I had the same issues you are having and it turned out to
be a cracked intake manifold...
Chip
P.S. Another thing you can try is to manually run a rubber fuel line from
the base of the fuel pump into a temporary gas can (1 gallon or 5 gallon)
and go out and drive the coach .... if it runs line then it helps you
isolate the problem backwards...
On Fri, Oct 8, 2010 at 10:08 AM, Heather Taft <taftheather@hotmail.com>wrote:
>
>
> Some additional information. We are currently in Wausaw, WI at the Chevy
> dealership because we were not sure where else to go and were towed in.
> - Our last fill up was with most likely with a gas that contained that
> contains up to 10% ethanel
> - The carb filter has been looked at and doesn't appear to be in backwards
> or wet from water.
> - We have now had two mechanics look at it and they are saying the problem
> is fuel starvation.
> - We were having issues with her stalling in 60 - 70 degree tempatures so
> not sure that vapor lock is our problem. She is stalling almost constantly
> at this time when starting up cold and at idle along with stalling when hot.
> - We only have a mechanical fuel pump which was just swapped out and that
> is not the issue. Have looked at the fuel filters and that doesn't appear
> to be it either.
> - We just under went a complete mechanical restoration so more of all the
> mechanicals are new or rebuilt (rebuilt engine, rebuilt carb, fuel pump,
> rebuilt distributor, cleaned out gas tanks, etc.)
>
> Another GMC owner last night stopped by when they saw us next to the
> Walmart and gave us the name of someone locally who works on this type of
> engine and carb. Waiting for the new carb to arrive today before next plan
> of action.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
. ___________
. /_][__] [ ] [ ]| 1977 Clasco 26'
. *O-------OO-----* aka "Mater"
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and lose of power) [message #102252 is a reply to message #102247] |
Fri, 08 October 2010 11:13 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Heather,
Since Ken Burton has offered to help -- please call him. A voice on the phone can be reassuring. And he knows the people who can help in that area.
He is on the Black List..
Dennis
| harborgal wrote on Fri, 08 October 2010 10:43 |
Day 6 at the repair shop.
Just called the number of the mechanic the local GMC owner provided and the shop was not very helpful. They are too busy to help and perhaps sometime next week they may get around to us if they have time. Does anyone else know someone in the area?? Another week in the Chevy lot will be too much for us.
So disappointed as this vacation is a bust. Just trying to get her repaired enough to get her back to the folks who did the restoration which is still a 12 hr drive to Michigian. So frustrated after dropping all the money that we spent restoring her mechanically.
|
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102255 is a reply to message #102211] |
Fri, 08 October 2010 11:16 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| Ken Burton wrote on Thu, 07 October 2010 23:54 |
I know of one good guy that lives about 120 miles from you. Let me see if he is in town. I know he was on the road a couple of weeks ago.
Ken B.
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I have been unable to locate the person I am looking for. I have to assume he is out of town. I left a message on his home phone for him to call me.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102258 is a reply to message #102255] |
Fri, 08 October 2010 11:33 |
Bill Massey
Messages: 201
Registered: March 2009
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Senior Member |
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I tried him also, Ken.
Reckon any of you in the twin cities could throw in a hand? Grean Bay is
even closer in case any of you have any ideas.
bdub
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Friday, October 08, 2010 11:17 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling,
and loss of power)
Ken Burton wrote on Thu, 07 October 2010 23:54
> I know of one good guy that lives about 120 miles from you. Let me see if
he is in town. I know he was on the road a couple of weeks ago.
>
> Ken B.
I have been unable to locate the person I am looking for. I have to assume
he is out of town. I left a message on his home phone for him to call me.
Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102268 is a reply to message #102193] |
Fri, 08 October 2010 13:02 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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If the coach is having problems running even at idle, as Ken B says it could be fuel or ignition. I'd think about taking the line of the carb or fuel pump and temporarily hook up something to catch fuel while cranking. Disable the ignition by your favourite method and crank the engine for 15 seconds and collect the fuel. If it is starving at idle you won't collect much fuel.
To check the ignition I'd hook the fuel system back up, and put the coil wire near ground and crank the engine without touching the gas pedal. Spark should be bright, possibly blue and should jump at least 1/4 inch, maybe more. The coil wire should make a steady stream of aparks while cranking. If the timing chain has jumped, a good old fashioned mechanic should be able to figure this out from where number 1 cylinder is "firing" vs where the timing mark is(assuming the outer ring on the dampener hasn't moved/slipped). Are you absolutely sure the tanks were really cleaned and the "socks" inspected and cleaned ????????
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102272 is a reply to message #102258] |
Fri, 08 October 2010 13:25 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| Bill Massey wrote on Fri, 08 October 2010 11:33 |
I tried him also, Ken.
Reckon any of you in the twin cities could throw in a hand? Grean Bay is
even closer in case any of you have any ideas.
bdub
|
I made contact with L.W. who just arrived home. He his going to call Bill who is the stranded GMCer.
I also talked to Heather at length on the phone. It turns out Heather has also been talking to Dick Paterson.
Thanks for the help Billy.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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