Home » Public Forums » GMCnet » LarC's power loss/stalling problem
| LarC's power loss/stalling problem [message #55182] |
Tue, 01 September 2009 21:04  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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LarC was working on his HVAC system when:
| Larry C wrote on Tue, 01 September 2009 13:48 |
THANK YOU everyone for your help and ideas.
This project just died as of the moment I tried to drive the GMC home and the problem I tried to solve for the last two years, power loss, this time at 30 mph and now stalling, has returned.
This problem showed its ugly face when the tanks were dropped to replace the rubber hoses. It went away, briefly after replacing the fuel pump, carburetor, distributor to electronic, checking fuel flows, and I forget what else has been done....
This is very discouraging for me and as for my trust in driving her, this has just tanked also.
The project now is to find this problem so I can use the coach someday.
Again, thanks for the ideas, I have saved them. Sorry to have brought up an old topic again. Thank you for entertaining my thoughts.
Gatsbys' CRUISER 
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LarC - this may be somewhat controversial to some but here is how I would pursue this problem if it was mine. I would remove the rubber fuel line from the engine driven fuel pump and plug it. I would then get an appropriate length of fuel line and attach it to the pump running it into the coach. Attach this line so it cannot get burned, move or become entangled in moving parts. Get a tank to mount in the coach interior, an outboard gas tank would be ideal but so would a 5 gal gas can, just don't fill it over 4 gallons, make sure it is well secured and will not move or spill. Go for a run that would normally cause the power problem to rear it's ugly head and see if it occurs, if the problem does not show up the problem is somewhere in the fuel system up to the pump. If the problem does turn up, it is not a fuel delivery problem from the tanks. This will narrow down the areas to search. I'm betting on the tanks because of the number of items you have done so far. My bet, rust in the tanks clogging the pickup screen.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55211 is a reply to message #55182] |
Wed, 02 September 2009 08:11  |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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Good input Steve, similar to what I had told him to do. Since you've had your fuel tanks out you obviously know all of the internal workings of them, you would understand the plugged screen thing more than I would.
I've continued to think it's an electrical or vacuum advance problem, but since the problem started after he dropped the tanks, it would make sense to drop them and check for this.
Ray
Ray & Lisa Erspamer
78 Royale Center Kitchen
The Malosco Cruiser (TZE368V101144)
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/
----- Original Message ----
From: Steve Southworth <midlf@centurytel.net>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, September 1, 2009 9:04:46 PM
Subject: [GMCnet] LarC's power loss/stalling problem
LarC was working on his HVAC system when:
Larry C wrote on Tue, 01 September 2009 13:48
> THANK YOU everyone for your help and ideas.
>
> This project just died as of the moment I tried to drive the GMC home and the problem I tried to solve for the last two years, power loss, this time at 30 mph and now stalling, has returned.
>
> This problem showed its ugly face when the tanks were dropped to replace the rubber hoses. It went away, briefly after replacing the fuel pump, carburetor, distributor to electronic, checking fuel flows, and I forget what else has been done....
>
> This is very discouraging for me and as for my trust in driving her, this has just tanked also.
>
> The project now is to find this problem so I can use the coach someday.
>
> Again, thanks for the ideas, I have saved them. Sorry to have brought up an old topic again. Thank you for entertaining my thoughts.
>
>
>
> Gatsbys' CRUISER :d
LarC - this may be somewhat controversial to some but here is how I would pursue this problem if it was mine. I would remove the rubber fuel line from the engine driven fuel pump and plug it. I would then get an appropriate length of fuel line and attach it to the pump running it into the coach. Attach this line so it cannot get burned, move or become entangled in moving parts. Get a tank to mount in the coach interior, an outboard gas tank would be ideal but so would a 5 gal gas can, just don't fill it over 4 gallons, make sure it is well secured and will not move or spill. Go for a run that would normally cause the power problem to rear it's ugly head and see if it occurs, if the problem does not show up the problem is somewhere in the fuel system up to the pump. If the problem does turn up, it is not a fuel delivery problem from the tanks. This will narrow down the areas to search. I'm betting on the tanks because of the number of items you
have done so far. My be
t, rust in the tanks clogging the pickup screen.
--
Steve Southworth
1974 Glacier TZE064V100150
Palmyra WI
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: LarC's power loss/stalling problem [message #55213 is a reply to message #55182] |
Wed, 02 September 2009 08:39 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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[quote title=midlf wrote on Tue, 01 September 2009 19:04]LarC was working on his HVAC system when:
| Larry C wrote on Tue, 01 September 2009 13:48 |
THANK YOU everyone for your help and ideas.
This project just died as of the moment I tried to drive the GMC home and the problem I tried to solve for the last two years, power loss, this time at 30 mph and now stalling, has returned.
|
A quick while crude test would be to pull the hatch when it has stalled. Pull the air cleaner and see if gas squirts in when you pump the accelerator. I would think that if it stalled, there could be little or no gas in the carb.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55217 is a reply to message #55211] |
Wed, 02 September 2009 09:19 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Ray, fast question
You mentioned you thought the Spark Plug Wires could be failing. Since this seems to happen at various speeds, now happening at 30 and has gotten bad enough to stall the engine, if the plug were bad dont you think it would have a problem ALL THE TIME?????
It seems intermittant right now, or maybe that is not the right word, it tends to happen when above 30 mph right now.
BACKGROUND
This started out in the beginning to occur at 50-55. After all the work, there was a breif period that it did not happen, then on the way home it began at 55. over the 6 hour drive home it degraded down to where I could not get over 30-35, haveing to coast over the slightest hills, through Milwaukee. and home to Illinois.
After replacing the fuel pump, it was gone. I drove it for ( best guess ) 75 miles at norm and highway speeds and thought it was gone. Now it is back. what can do that?
btw - can anyone tell me if the water separator needs maintenance? does it need to be drained, and if so HOW? We glanced at it yesterday and it seems to be a solid item with no maintenance port.
Guys, I wasn't going to bring this one up on the forum. Someone else mentioned it in my stead, thank you. I am really bummed on this occurance.
I appreciate your help, you are the greatest, that is what makes the GMC net what it is I guess.
This one has me baffled and I've about had it with this problem.
I am moving ahead with the mechanics support, many of the steps we are repeating from the past, don't know what we missed.
Thanks again for all your support.
Gatsbys' CRUISER
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
[Updated on: Wed, 02 September 2009 09:31] Report message to a moderator |
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55223 is a reply to message #55210] |
Wed, 02 September 2009 10:07 |
rjw
Messages: 697
Registered: September 2005
Karma: 4
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Jim,
You know you can't get away without showing us a description and picture of
how you mounted your gauge.
Richard
SE Michigan
Website: www.PalmBeachGMC.com
> If I may offer a suggestion. Install a fuel pressure gauge by putting a
> "T" fitting in the line between the pump and carb. I have a fuel
> pressure gauge that is permanently mounted on the OUTSIDE drivers
> mirror. I got mine from www.summitracing.com. This would help determine
> if your problem is fuel or electrical. Zero pressure would be a good
> sign of a fuel problem.
> Jim Wagner
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Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com
Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55287 is a reply to message #55284] |
Wed, 02 September 2009 16:27 |
Ernest Dankert
Messages: 133
Registered: May 2007
Location: Ogden, New York
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That unit in the LR fender well is a gas/air separator that prevents liquid gas from going up to the charcoal scrubber.
My 1977 GMC had a similar problem, steadily decreasing power, ever slower speeds. Thats a fuel delivery issue, look for a collapsing fuel line, pinched fuel line, dirty socks in the tank, plugged fuel filter or in my case the innerds had crumbled to small chunks of rubber in the electric fuel pump.
The quadrajet is very sensitive to fuel level.
1977 Eleganza II
Ogden NY
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55288 is a reply to message #55284] |
Wed, 02 September 2009 16:28 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
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| Larry C wrote on Wed, 02 September 2009 13:36 |
I'm guessing you're referring to the fuel/vapor separator in
the tank-vent-to-charcoal cannister line?
______________________________________________
No, this water separator, so I am told it is, is located rear wheel well, driver side. It is under some tin, looks pretty solid from a glancing view. I thought I would ask before I broke something else.
Gatsbys' CRUISER
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Larry is correct. The triangular plastic separator located in the front of the left rear wheel well is the fuel/vapor separator. It does connect the vent in the tanks to the charcoal canister. It keeps raw gasoline from getting in the charcoal canister. Be careful with it as it is breakable and fairly expensive to replace.
This is part of the "smog" stuff and one that makes sense. Fuel vaporizes and expands when warm. The vapor could burp out into the air, but instead got into the charcoal canister. The good part is when driving, the vapor is sucked into the engine. You get to use fuel that would have been polluting the air as hydrocarbons.
If it is not working you will often have quite a bit of pressure or vacuum at the gas cap.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
[Updated on: Wed, 02 September 2009 16:30] Report message to a moderator |
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55302 is a reply to message #55284] |
Wed, 02 September 2009 17:27 |
tmaki
Messages: 200
Registered: September 2005
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Larry wrote:
>
> I'm guessing you're referring to the fuel/vapor separator in
> the tank-vent-to-charcoal cannister line?
> ______________________________________________
>
> No, this water separator, so I am told it is, is located rear wheel well, driver side.
Right. That's the liquid fuel/vapor separator. See Section 8
of the service manual.
> It is under some tin, looks pretty solid from a glancing view.
It rattles like an empty spray paint can if all is well with it.
> I thought I would ask before I broke something else.
That's smart. But I'm not convinced it's all that fragile.
Look at where it lives. Sure, you could break the hose barbs
off, man-handle it in such a way as to crack it. But it just
comes off with two little bolts.
I've just had mine off, along with that Nevada-shaped plate
it's mounted to. Blasted, rust converted and undercoated the
plate and the sheetmetal box around the separator. Cleaned
out the separator with brake cleaner and compressed air.I
re-mounted everything with SS bolts, washers and nylon lock
nuts. Re-plumbed it this morning with all new hoses.
This, by way of saying that there isn't any magic in that
thing. And certainly none, in my opinion, that would cause
your performance issues. Pull the top hose off of it and see
if it makes any difference.
You could always trace out the vacuum hose running to the
charcoal cannister under the frame behind the right front
wheel. There's a Mongo-sized vacuum leak if that puppy is
bad. I pulled all that off this morning, too, and plugged
the port on the carburetor. I didn't have any vacuum leak,
but what a mess. I'll clean it up and maybe put it back on
later.
Keep trying stuff. You'll find whatever it is that's causing
you grief.
Toby Maki
'73 Glacier 230
Riverside, CA
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| Re: [GMCnet] LarC's power loss/stalling problem [message #55342 is a reply to message #55302] |
Wed, 02 September 2009 22:22 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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OK - two more thoughts. You can quickly determine if the problem is caused by inadequate venting of the fuel tanks. This could be caused by a defective or improper gas cap AND an improperly operating vent system. When the problem occurs loosen the gas cap, leave it loose and continue to drive. If the problem goes away it would appear you have vacuum on the fuel tanks.
LarC - you stated the fuel tanks were attended to when at JimB's. Were the interiors coated with any type of product? I don't know about GMC tanks but I know some motorcycle tanks that were coated internally have had the coating release from the tank walls and intermittently plug the fuel pickup.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] LarC's power loss/stalling problem [message #56081 is a reply to message #55284] |
Sun, 06 September 2009 20:49 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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On Sep 2, 2009, at 2:36 PM, Larry wrote:
>
>
> I'm guessing you're referring to the fuel/vapor separator in
> the tank-vent-to-charcoal cannister line?
> ______________________________________________
>
> No, this water separator, so I am told it is, is located rear wheel
> well, driver side. It is under some tin, looks pretty solid from a
> glancing view. I thought I would ask before I broke something else.
>
>
>
> Gatsbys' CRUISER :d
> --
> LarC - N/E Illinois
> 74 GLACIER X, "Gatsbys' CRUISER"
> 260/455/APC/4 bagg'r(ver3)
> Remflex Manifold gaskets
Larry, you are giving a very good description of a liquid/vapor
separator that allows the gasoline vapors to go forward through a hose
to a carbon cannister that is located below the front passenger seat.
it keep the liquid from going there.
The vapors are then drawn into the carb and burnt.
The GMC motorhome doesn't have a "water searator", so whoever told you
that, told you wrong! :)
Emery Stora
77 Kingsley
Santa Fe, NM
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