| [GMCnet] Vapor lock and other fuel supply problems [message #344120] |
Tue, 11 June 2019 06:36  |
Dave
Messages: 32
Registered: March 2004
Karma: 3
|
Member |
|
|
Looks like it is vapor lock season again. Back in 2013 I did a bunch
of upgrades to my fuel system to solve a number of fuel supply
problems. I started posting the pics to the gmcmh photos site but got
side-tracked and forgot to finish the uploads. I was recently asked
about my in-tank fuel pump upgrade which reminded me that I should
really finish my post to the photos site. Especially now that a few
years have passed and the upgrades seem to have solved the various
problems that I was having. If you are having any of these problems,
hopefully this collection will help.
Dave
Ann Arbor, MI.
73 Sequoia (26'/455/EbH/RwI/ThH/HEI/TBI/160°/3.42/100A/Q55G)
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
|
|
| Re: [GMCnet] Vapor lock and other fuel supply problems [message #344124 is a reply to message #344120] |
Tue, 11 June 2019 09:21  |
rvanwin
Messages: 325
Registered: April 2007
Location: Battlefield, MO
Karma: 6
|
Senior Member |
|
|
Dave wrote on Tue, 11 June 2019 06:36
Looks like it is vapor lock season again. Back in 2013 I did a bunch
of upgrades to my fuel system to solve a number of fuel supply
problems. I started posting the pics to the gmcmh photos site but got
side-tracked and forgot to finish the uploads. I was recently asked
about my in-tank fuel pump upgrade which reminded me that I should
really finish my post to the photos site. Especially now that a few
years have passed and the upgrades seem to have solved the various
problems that I was having. If you are having any of these problems,
hopefully this collection will help.
Just a word of warning on the E3902. This pump was recommended by Bill Bramlet and Emery Stora when they developed and documented the in-tank pump setup found in the GMCMI Technical Documents web site. I installed these in-tank pumps many years ago and did not have any problems for many years until I got a load of dirty gas (the gas station pump filter failed, I think). I had to drop the tanks to replace the socks that were almost block by crud. After cleaning everything up, I decided to replace the pumps while I was there. I started to have loss of power issues that I could not explain except that fuel pressure was below the 16 to 18 psi that Howell's injectors require. I thought that the socks had become blocked again. I dropped the tanks - socks were in great shape. So, I ordered new pumps but this time I checked the specs. The minimum pressure is rated at 12 psi while the max is around 18 psi. I found this strange and found an old listing that showed the specs with higher numbers. I think Airtex must have changed the specs on this pump. This pump is used on an S10 Chevy Pickup. They list another pump used on the port injected models that has the same fitment so I ordered two of these pumps and have not had anymore problems with fuel pressure. Anyway, you might want to monitor your fuel pressure in order to make sure you are getting enough pressure for the Holley injectors. This pump should be OK for the Rochester TB and maybe for early Howell systems that used the large injectors because their requirement is between 10 and 13 psi.
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
|
|
|
|
| Re: [GMCnet] Vapor lock and other fuel supply problems [message #344152 is a reply to message #344124] |
Wed, 12 June 2019 08:44 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
|
Senior Member |
|
|
Pressure I should be considered, but also the volume.
Keep in mind the Cubic inch does demand mor than a smaller even if the RPM
is lower.
Randy, what's your thoughts on adjusting the pressure regulator at the
throttle body?
On Tue, Jun 11, 2019 at 7:25 AM Randy Van Winkle via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Dave wrote on Tue, 11 June 2019 06:36
>> Looks like it is vapor lock season again. Back in 2013 I did a bunch
>> of upgrades to my fuel system to solve a number of fuel supply
>> problems. I started posting the pics to the gmcmh photos site but got
>> side-tracked and forgot to finish the uploads. I was recently asked
>> about my in-tank fuel pump upgrade which reminded me that I should
>> really finish my post to the photos site. Especially now that a few
>> years have passed and the upgrades seem to have solved the various
>> problems that I was having. If you are having any of these problems,
>> hopefully this collection will help.
>
> Just a word of warning on the E3902. This pump was recommended by Bill
> Bramlet and Emery Stora when they developed and documented the in-tank pump
> setup found in the GMCMI Technical Documents web site. I installed these
> in-tank pumps many years ago and did not have any problems for many years
> until I got a load of dirty gas (the gas station pump filter failed, I
> think). I had to drop the tanks to replace the socks that were almost block
> by
> crud. After cleaning everything up, I decided to replace the pumps while I
> was there. I started to have loss of power issues that I could not explain
> except that fuel pressure was below the 16 to 18 psi that Howell's
> injectors require. I thought that the socks had become blocked again. I
> dropped the
> tanks - socks were in great shape. So, I ordered new pumps but this time I
> checked the specs. The minimum pressure is rated at 12 psi while the max is
> around 18 psi. I found this strange and found an old listing that showed
> the specs with higher numbers. I think Airtex must have changed the specs on
> this pump. This pump is used on an S10 Chevy Pickup. They list another
> pump used on the port injected models that has the same fitment so I ordered
> two of these pumps and have not had anymore problems with fuel pressure.
> Anyway, you might want to monitor your fuel pressure in order to make sure
> you are getting enough pressure for the Holley injectors. This pump should
> be OK for the Rochester TB and maybe for early Howell systems that used the
> large injectors because their requirement is between 10 and 13 psi.
>
> --
> Randy & Margie
> '77 Eleganza II '403'
> Battlefield, MO
>
> _______________________________________________
> 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
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
|
|
|
|
|
|
| Re: [GMCnet] Vapor lock and other fuel supply problems [message #344189 is a reply to message #344152] |
Thu, 13 June 2019 15:40 |
rvanwin
Messages: 325
Registered: April 2007
Location: Battlefield, MO
Karma: 6
|
Senior Member |
|
|
jimk wrote on Wed, 12 June 2019 08:44Pressure I should be considered, but also the volume.
Keep in mind the Cubic inch does demand mor than a smaller even if the RPM
is lower.
Randy, what's your thoughts on adjusting the pressure regulator at the
throttle body?
Flow is important so always check the specs. However, high pressure pumps seldom have problems with flow / volume. Pressure, however, is important and the min spec of the pump should be above that of the TB regulator. The GM Rochester TBs do not have adjustable regulators so they are set at whatever the injector requirements are. Most for the large Rochester found on 454s are spec'd between 10 and 13 psi. Some, on later '94 - '95 454s are spec'd between 28 and 30. These are approximate numbers without going to look up the actuals. The Holley TB that is used on Howell EFI kits has an adjustable regulator. Several years ago, Howell changed the injectors to smaller ones but did not make any adjustments to the pressure regulator. Not enough pressure was being delivered to adequately supply our engines so some were experiencing stumbles at tip-in or loss of power on hard pulls. Once we discovered this, we recommended that the pressure be increased to at least 18 psi which solved those issues. 20 psi would be better but the Holley regulator is not too stable above 18 psi. This also requires a new tune for the ECM. I haven't heard of too many problems on current kits so I guess that the regulator has been "turned up" by Howell. I almost always recommend anyone installing an EFI system to add a pressure sensor or at least temporarily check the fuel pressure because you can chase a lot of false symptoms before solving a performance issue. Best to insure you have the proper psi being delivered and this recommendation doesn't matter what EFI system you choose to install.
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
