Home » Public Forums » GMCnet » [GMCnet] Heat, pumps, and the gas tanks.
| [GMCnet] Heat, pumps, and the gas tanks. [message #332346] |
Sun, 20 May 2018 13:45  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma:
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Senior Member |
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Heating of the gas is an issue that seems to come up a lot. So when I installed the Howell system. I thought of in tank pumps. So that the fuel is under pressure from inside the tanks. To the TB. This concept has true merit. But I've had too many pumps from China that failed. I wanted both tank pumps simple/quick to get too. So I put the two pumps for my EFI on the outside of the main steel frame. Plus. In an attempt to get away from engine heat that's more prevalent inboard of that steel frame. Plus back to the simplicity of the service concept. That did prove out way sooner then I ever expected. As one of the EFI pumps failed after only 6 blocks into my first test run of the EFI. The aux tank pump got me back home. Pump change took about 15 minutes. Now back to the heat. Most of the heat is coming from the engine. The extreme heat goes out the back by way of the tail pipe. Header displace a lot of the heat into the engine bay. That originally went out the tail pipe, back from the gas tanks. Thus headers acerbating the heating of the gas tanks. There are vents that can be put in the body, above the front wheels. These vents are about straight out board of the headers. This header heat leaves the engine bay by way of under the gas tanks. Our GMC doesn't have headers. Does still have the GM gas tank exhaust pipe heat shields. ( Did make mine taller. No surprise that I'd do that kind of thing.) Last year I was monitoring tank temps. I was very surprised as to how high tank temps got. Gas temps at the outboard pumps was at the tank temps. So no gas temp rise to the pumps.
Has anyone put gas tank heat shields bellow their gas tanks. Then a cool air duct to the outside of the tanks? Bob Dunahugh
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From: gmcmh-efi@googlegroups.com on behalf of Randy Van Winkle
Sent: Sunday, May 20, 201:58 AM
To: gmcmh-efi@googlegroups.com
Subject: Re: [GMCMH-EFI] Fuel Pump Questions
Seems like more complication than necessary. I would wait until you were ready to install the efi system (sounds like you are close to doing that anyway) then remove the sometimes troublesome fuel selector switch and intall two high pressure pumps as close to the tanks as possible or in the tanks if you are up to the extra work. To me the low pressure oump is just added complication.
If you need the low pressure electric for the carb to prevent vapor lock until you do the efi then install an inexpensive pump to feed the mechanical. Remove it when you go to efi. The goal is to keep fuel under pressure from tanks to engine.
Randy (liking simplicity)
'77 Eleganza II "403"
On Sat, May 19, 2018, 8:51 PM Ty Hardiman wrote:
Thanks all. I've gotten some useful information to think about. I realize there are many ways to lay out the fuel supply system. But my takeaway is this:
Q: What are the opinions about using a low-pressure external pump to feed the high-pressure external pump.
A. It's a hedge against vapor lock. And if you installed a bypass loop with a check valve on the low-pressure pump, the high-pressure pump would work with or without the low pressure pump operating.
On Saturday, May 19, 2018 at 7:17:39 PM UTC-5, Larry Davick wrote:
Unless you have an urgent need to replace the mechanical fuel pump, I would wait. I don’t see a good reason to put an electric pump in place when it’s really not needed. I did this and regretted it. My tired old carb was not happy with the pump and despite some fiddling I was not ever happy I’d replaced the pump. It finally worked perfectly, but it did not improve the stock set-up in any way for me.
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor
On May 18, 2018, at 8:01 PM, Ty Hardiman wrote:
Fair enough. Let me expand my question:
I would like to install electric fuel pumps on my coach, with my q-jet. Upgrading later to a Rochester TBI. I can put in a pair of 4070s now, but would that be wasted money if I'm just going to go to an Airtex + EFI in a few months? Or would it be beneficial to feed the dual 4070's into an Airtex?
On Friday, May 18, 2018 at 9:41:49 PM UTC-5, Ty Hardiman wrote:
Hello all, first post. What a great resource this forum is! I have spent a lot of time over the past month reading the forum posts and the related resources, working on understanding EFI for the GMCMH.
I'm in the "learning, thinking, & planning" phase and I'll try to ask concise and specific questions. I'm doing some fuel pump planning right now.
Q: What are opinions on using a Carter 4070 to supply an Airtex 8094 - is this required, not required but beneficial, or completely unnecessary?
Thanks in advance,
Ty
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[GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
By: lw8000 on Mon, 21 May 2018 11:05 |
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
By: lw8000 on Wed, 23 May 2018 15:09 |
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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Re: [GMCnet] Heat, pumps, and the gas tanks.
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