Home » Public Forums » GMCnet » Re: [GMCnet] Vapor lock feedback
| Re: [GMCnet] Vapor lock feedback [message #318489] |
Sun, 04 June 2017 21:51  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Sounds about right to me. Keep your tanks full of cool fuel, travel early
in the day. That's about it. Summer blend fuel only.
Jim Hupy
On Jun 4, 2017 7:47 PM, "Chris S." wrote:
Hello all:
I was looking for some additional feedback on vapor lock, mainly what kind
of conditions that you have seen it in. We seem to be troubled by it when
temps get up over 83-85 degrees outside, it first started last summer going
down the Florida where temps got up to 93+. Since then, we've had an
inline fuel pump and rebuilt carb installed by JimB, that seems to have
done the trick for getting around the issue (which only seems to happen when
slowing down or stopping and trying to get going again).
Also since the inline fuel pump, we've had an aluminum ported Offenhauser
intake manifold installed, with the Paterson blockoff kit. We had this done
due to cracking of the original manifold. Some thought maybe this would
help with vapor lock, however today we again had it happen to us, temps
outside were around 83-84 degrees with full sun, we were on the highway for
about 45 minutes after taking off cold. After exiting the highway,
stopping at a sign, and accelerating again on a backroad, after 10 seconds
while accelerating the engine starting surging a little bit. After
flipping on the electric aux pump, the surging went away after about 15-20
seconds. We were running the dash AC at the time as well.
Does this seem to be a little bit extreme with it happening when it's 83-84
degrees out, or is this pretty much what everybody else is experiencing?
And is the main fix still just using an aux electric pump back near the
tanks? I can't imagine this could be anything else besides vapor lock.
Over
the years we've had everything in the fuel system either replaced or fixed:
fuel tanks cleaned & coated, new rubber hoses & fuel filter, new solenoid,
new inline fuel pump and fuel system check (by JimB), new Carter mechanical
fuel pump, rebuilt carb (from JimB), new aluminum intake, and even a new
fan clutch (Delco 15-4947). Everything seems to be in order.
Feedback, thoughts and anything else is more than welcome. Thanks all!
Chris
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
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| Re: [GMCnet] Vapor lock feedback [message #318503 is a reply to message #318489] |
Mon, 05 June 2017 08:37  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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How hot was the road bed? The low, flat, large surface area of our fuel tanks will absorb road heat easily. Hot gas will cause conditions very similar to vapor lock. Some have painted the bottom of the gas tanks to reflect road heat.
You might see if you have shielding between the gas tanks and the exhaust pipe. No sense in adding heat to the gas in the tank.
Here in Alabama, Summer afternoons are tough for vapor lock.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] Vapor lock feedback [message #318547 is a reply to message #318489] |
Mon, 05 June 2017 15:56 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I have been over this on the net, and done presentations at several rallies
on the West Coast about what many here describe as vapor lock. Don't know
if that is an exact term or not, but, for those of you out there in
GMCVILLE who are having issues with driveability of their coaches on days
warmer than 85 degrees or so, I will try to aproach how to deal with it,
not what causes it.
1. Get rid of your winter fuel.
2. Run with your tanks as full as possible.
3. Drive early in the day when it is cooler.
4. Keep your filters clean, carry spares.
5. Install an inline electric fuel pump after the selector valve.
6. Use ethanol free fuel if possible.
Most of the time, this is all that is needed. The problem is NOT WITH YOUR
COACH. IT IS WITH THE FUEL. So, fixing the coach is NOT going to make your
problems go away totally.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jun 5, 2017 1:37 PM, "Chris S." wrote:
Tony Cook wrote on Mon, 05 June 2017 15:00
> I second the little Qjet filter only takes a little shmoots that will
cause this same issue. It may not be your issue but they are cheap and I
> keep a few in the glove box and replace from time to time. Even though my
fuel system has been redone ie. tanks sealed,fuel lines replaced etc . I
> too have aux carter and hit it when she starts to stumble seems to help
but it has done it to me even with the aux pump on. Has anyone had any luck
> with the 3 port/return line mechanical pump the Toros had on them to
remedy VL ?
We ended up also installing an inline metal filter between the metal line
and fuel pump inlet to help keep stuff from getting to the pump, just in
case. Super easy to change out if needed, and is a little larger than the
one at the carb. For what it's worth.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
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| Re: [GMCnet] Vapor lock feedback [message #318550 is a reply to message #318489] |
Mon, 05 June 2017 19:14 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Dump #5, install two electric pumps, and use the tank selector to also select the pump. 50 bux more than one and a simpler setup as well. Cap the selector valve and toss the mechanical pump in the tool box and you can conver to it in 30 minutes beside the road should the need arise. (It never did)
--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: [GMCnet] Vapor lock feedback [message #318559 is a reply to message #318547] |
Mon, 05 June 2017 23:20 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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For any pump to pull through and push is not the issue.
When gasoline is drawn through the filter, there is a differential pressure
created that invites vapor pockets.
To avoid that to some degree, we use high capacity filter cartridges that
has lower pressure drop.
Larger capacity has 3-4 times more media area so the particulets are spread
out on the media to where the restriction climbs up at a much slower rate.
On Mon, Jun 5, 2017 at 1:56 PM, James Hupy wrote:
> I have been over this on the net, and done presentations at several rallies
> on the West Coast about what many here describe as vapor lock. Don't know
> if that is an exact term or not, but, for those of you out there in
> GMCVILLE who are having issues with driveability of their coaches on days
> warmer than 85 degrees or so, I will try to aproach how to deal with it,
> not what causes it.
> 1. Get rid of your winter fuel.
> 2. Run with your tanks as full as possible.
> 3. Drive early in the day when it is cooler.
> 4. Keep your filters clean, carry spares.
> 5. Install an inline electric fuel pump after the selector valve.
> 6. Use ethanol free fuel if possible.
> Most of the time, this is all that is needed. The problem is NOT WITH YOUR
> COACH. IT IS WITH THE FUEL. So, fixing the coach is NOT going to make your
> problems go away totally.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Jun 5, 2017 1:37 PM, "Chris S." wrote:
>
> Tony Cook wrote on Mon, 05 June 2017 15:00
>> I second the little Qjet filter only takes a little shmoots that will
> cause this same issue. It may not be your issue but they are cheap and I
>> keep a few in the glove box and replace from time to time. Even though my
> fuel system has been redone ie. tanks sealed,fuel lines replaced etc . I
>> too have aux carter and hit it when she starts to stumble seems to help
> but it has done it to me even with the aux pump on. Has anyone had any luck
>> with the 3 port/return line mechanical pump the Toros had on them to
> remedy VL ?
>
>
> We ended up also installing an inline metal filter between the metal line
> and fuel pump inlet to help keep stuff from getting to the pump, just in
> case. Super easy to change out if needed, and is a little larger than the
> one at the carb. For what it's worth.
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
> 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
>
--
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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