Home » Public Forums » GMCnet » Up hill hesitation
| Up hill hesitation [message #346411] |
Wed, 14 August 2019 07:07  |
Wardhill
Messages: 63
Registered: May 2019
Location: West Baldwin, Maine
Karma: -1
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I'm getting a hesitation /stall situation when going up steep hills. Unfortunately I live up one. I,ve replaced the carb filter and checked vacuum line connections.. today I,ll give the whole thing a sea foam treatment hopefully that will help. Hoping to get to the nor'easter chapter rally in Vermont this weekend. Its a 2 1/2 hour trip any tips to check would be most appreciated
Thank,
Jeff
Jeffrey Fleming
1976 edgemonte
Living in Maine
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| Re: Up hill hesitation [message #346416 is a reply to message #346411] |
Wed, 14 August 2019 08:45  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Sir: possibly the pickup socks in the tanks are clogged up. Maybe try switching tanks. I have had some success removing gas cap and blowing shop air back thru the rubber hose coming out of the switching valve then switching the valve and doing the other tank pick up.
Wardhill wrote on Wed, 14 August 2019 08:07I'm getting a hesitation /stall situation when going up steep hills. Unfortunately I live up one. I,ve replaced the carb filter and checked vacuum line connections.. today I,ll give the whole thing a sea foam treatment hopefully that will help. Hoping to get to the nor'easter chapter rally in Vermont this weekend. Its a 2 1/2 hour trip any tips to check would be most appreciated
Thank,
Jeff
C. Boyd
76 Crestmont
East Tennessee
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| Re: Up hill hesitation [message #346418 is a reply to message #346411] |
Wed, 14 August 2019 08:57 |
Wardhill
Messages: 63
Registered: May 2019
Location: West Baldwin, Maine
Karma: -1
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I have not replaced my fuel lines only had the coach since June hoping to get it looked over by mike at New England rv but something always comes up where I can't make my appointment. Had no problems driving this from Wisconsin to maine although I do remember experiencing some hesitation coming out of Detroit but that was a one time thing. This seems to occur only under load. Idles great
Jeffrey Fleming
1976 edgemonte
Living in Maine
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| Re: Up hill hesitation [message #346422 is a reply to message #346411] |
Wed, 14 August 2019 09:44 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Idles great, only stagger was under load? Look tofuel lines and filters. If the lines arebn't barrier hose, drop the tanks and replace ALL the rubber. This is one that isn't particularly hard, but it is time consuming. Do it yourself for a hundred or less in hoses and a couple of ratchet straps. Hire it done and you're going to buy several hours of labor at a hundred an hour more or less. Let your pocket be your guide.
--johnny
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: Up hill hesitation [message #346426 is a reply to message #346422] |
Wed, 14 August 2019 10:01 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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What Johnny said...lines are probably soft, collapsing under high fuel flow. And Chuck is probably right about the filter socks being partially clogged causing more suction on the hoses than normal that will definitely collapse weakened hose.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Up hill hesitation [message #346428 is a reply to message #346426] |
Wed, 14 August 2019 10:32 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Fuel hoses could also be cracked and sucking air. This fuel starvation is a common problem with this fuel system. It's not truly "vapor Lock" but similar as the gas vaporizes in the lines and the carburetor runs out of gas. An electric fuel pump near the tanks usually clears it up.
I fought this for years and finally remedied it by moving my fuel hoses to the outside of the frame and added a carter 4070 fuel pump, along with a cartridge filter, on my aux tank. Even on my last two mid Summer trips (in Arizona heat) I didn't have a problem.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Up hill hesitation [message #346434 is a reply to message #346411] |
Wed, 14 August 2019 11:42 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Sure sounds like fuel starvation. If it does it every time you go up that hill then it probably is not vapor lock. If it is only occasionally, then do not rule out the vapor lock problem.
Since the coach is new to you look for an added fuel filter somewhere. Usually POs install then in the rubber line on the input to the fuel pump, or by the selector valve, or in the pick up lines to both tanks.
Also could be a weak fuel pump. If it doubt, replace it. They are cheap.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Up hill hesitation [message #346446 is a reply to message #346434] |
Wed, 14 August 2019 16:36 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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I get about two calls a day on fuel issue.
They ALL have not replaced the fuel lines, tank selector valve, vapor
separator and mechanical pump.
They ALL have Old rubber, so they need to be replaced.
On Wed, Aug 14, 2019 at 9:42 AM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Sure sounds like fuel starvation. If it does it every time you go up that
> hill then it probably is not vapor lock. If it is only occasionally, then
> do not rule out the vapor lock problem.
>
> Since the coach is new to you look for an added fuel filter somewhere.
> Usually POs install then in the rubber line on the input to the fuel pump,
> or
> by the selector valve, or in the pick up lines to both tanks.
>
> Also could be a weak fuel pump. If it doubt, replace it. They are
> cheap.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Up hill hesitation [message #346451 is a reply to message #346411] |
Wed, 14 August 2019 17:48 |
Jim Miller
Messages: 501
Registered: March 2008
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On Aug 14, 2019, at 8:07 AM, Jeffrey Fleming via Gmclist wrote:
> I'm getting a hesitation /stall situation when going up steep hills. […] This seems to occur only under load. Idles great
I completely agree with what everyone else has said regarding fuel delivery and the importance of good hoses and filtering.
I will, however, also point out that these same exact symptoms can occur if there are one or more things in the ignition system that are spongy. As fuel mixture and cylinder pressures increase during steep hill climbs and other high load events (like aggressive acceleration) the dielectric characteristic of the fuel/air mix in the cylinders will change and higher voltages are necessary to ionize the gap between the spark plug electrodes. If something is compromised in the ignition system such as a tired coil, dirty rotor or cap contacts or even wires that have developed high resistance then strong sparks may not reliably occur on every power stroke during the conditions described.
It would be interesting to know if the hesitation and stumbling occurs immediately upon application of increased load (pointing to an ignition problem) versus some non-trivial amount of time after the load is applied which would indicate fuel starvation.
—Jim
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: Up hill hesitation [message #346455 is a reply to message #346411] |
Wed, 14 August 2019 18:01 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Moving the fuel lines to the outside of the frame rails is fine till you get T boned. Then you have a potential emulation of the Crown Vic/ Pinto rear ended fire after crash.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Up hill hesitation [message #346463 is a reply to message #346411] |
Thu, 15 August 2019 07:43 |
Wardhill
Messages: 63
Registered: May 2019
Location: West Baldwin, Maine
Karma: -1
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No the hesitation happens at some point during the ascent. I'll try changing out the fuel filter before redoing all of the lines. Last trip around the block it made it up the hill. But there was still some hesitation just prior. It was then I noticed the filter spring sitting on top of the block. Duh! This was after replacing carb filter. All back together correctly now. This engine was supposedly rebuilt 40,000 miles ago . I,ll look to see if fuel line replacement were mentioned in any of the paper work I have . They don't look 45 years old from what I can see but have yet to find any markings on them.
Thanks everyone
Jeffrey Fleming
1976 edgemonte
Living in Maine
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| Re: Up hill hesitation [message #346466 is a reply to message #346411] |
Thu, 15 August 2019 08:18 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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"I'll try changing out the fuel filter before redoing all of the lines."
If they are older, you're riding for a fall and a chance of setting the woods on fire. Change EVERY rubber hose on the coach which isn't barrier hose.
--johnny
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: Up hill hesitation [message #346468 is a reply to message #346466] |
Thu, 15 August 2019 08:26 |
Wardhill
Messages: 63
Registered: May 2019
Location: West Baldwin, Maine
Karma: -1
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Guess it should be done regardless. Who sells the correct hose? Is there a diy write up someplace on this topic?
Thanks
Jeffrey Fleming
1976 edgemonte
Living in Maine
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| Re: [GMCnet] Up hill hesitation [message #346483 is a reply to message #346466] |
Thu, 15 August 2019 13:18 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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the next time I change my fuel lines, because mine are now 10 years old, I will be using nylon and push lock connects.
This will solve 2 problems:
1. it's a ton easier to use than steel lines, bending is a non issue
2. It will eliminate all rubber connections between the steel lines however short
3. It makes it easy to remove and replace the tanks
________________________________
From: Gmclist on behalf of Johnny Bridges via Gmclist
Sent: Thursday, August 15, 2019 8:18 AM
To: gmclist@list.gmcnet.org
Cc: Johnny Bridges
Subject: Re: [GMCnet] Up hill hesitation
"I'll try changing out the fuel filter before redoing all of the lines."
If they are older, you're riding for a fall and a chance of setting the woods on fire. Change EVERY rubber hose on the coach which isn't barrier
hose.
--johnny
--
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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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Up hill hesitation [message #346484 is a reply to message #346483] |
Thu, 15 August 2019 13:39 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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If you really want bulletproof fuel lines, the best is metal. Properly
bent, secured, and flared. Use DOT approved fittings, of coarse.
Next is braided covered fuel lines that are Alcohol Resistant, AN
fittings and exacting workmanship. Secure them properly, protect them from
heat and collision damage.
Next would be Gates "Barricade" fuel hoses. Use full circle fuel
injection hose clamps. There again, protect it from heat and collision
damage. Check this every spring, and replace it at the first sight of any
age related issues.
Never, never, never any rubber hose between the mechanical fuel pump and
carb. No in-line filters here either, that is what the carb filter is for.
Jim Hupy
Salem, Or
On Thu, Aug 15, 2019, 11:19 AM Keith V via Gmclist
wrote:
> the next time I change my fuel lines, because mine are now 10 years old, I
> will be using nylon and push lock connects.
> This will solve 2 problems:
>
> 1. it's a ton easier to use than steel lines, bending is a non issue
> 2. It will eliminate all rubber connections between the steel lines
> however short
> 3. It makes it easy to remove and replace the tanks
>
> ________________________________
> From: Gmclist on behalf of Johnny
> Bridges via Gmclist
> Sent: Thursday, August 15, 2019 8:18 AM
> To: gmclist@list.gmcnet.org
> Cc: Johnny Bridges
> Subject: Re: [GMCnet] Up hill hesitation
>
> "I'll try changing out the fuel filter before redoing all of the lines."
>
> If they are older, you're riding for a fall and a chance of setting the
> woods on fire. Change EVERY rubber hose on the coach which isn't barrier
> hose.
>
> --johnny
> --
> 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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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