| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 123.1 | Another question | DNEAST::GENESEO_PAUL | | Tue Oct 26 1993 07:35 | 5 |
| While we're on the subject of Firebird fuel pumps, I have a question.
The steel fuel line running from the pump to the carb pulses back and
forth while its idling and vibrates as the rpm's increase. Is this
common or is something wrong with the pump. It is a new pump and I
never noticed if the old pump did the same thing or not.
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| 123.2 | No doubt it shouldn't. | CXCAD::C_WILLIAMS | Hammer | Tue Oct 26 1993 09:24 | 2 |
|
Mine doesn't do it and I also have a new pump.
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| 123.3 | The awaited answer | CUJO::BROWN | Dave Brown | Wed Dec 15 1993 13:24 | 16 |
|
I've got no problem with fuel delivery on my Firebird. I used a
Mallory high-performance mechanical pump which fits in place of the
stock pump. I was considering using an electric pump but my feeings
that electricity and gasoline don't mix (unless in the cylinder)
prevented me from doing that. I wrapped the fuel line with reflective
heat tape where it goes near the exhaust and made sure it was tied down
tightly. I used all 3/8" fuel line.
As a result, my fuel pressure gauge on the fuel delivery manifold
attached to my carb never varies from about 7 psi. I have no vapor
locks nor unreliable fuel delivery. The system goes through alot of gas
too at 7 MPG.
Dave
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| 123.4 | I used 3/8" hose | CUJO::BROWN | Dave Brown | Wed Dec 15 1993 13:27 | 11 |
|
re: .1
I've got a 3/8 fuel hose going between the pump and carb. In fact,
I have 3/8" hose on the supply and return lines too all the way up to
the steel lines that come up the right frame mount. Heavily wrapped
with reflective heat tape of course...
Works for me...
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| 123.5 | Thanks again! | CXCAD::C_WILLIAMS | Hammer | Thu Dec 16 1993 12:39 | 21 |
|
Thanks for the input, Dave. I have a buddy with a '72 400 and he is
experiencing the vapor locking problem as well. Both of us are running
3/8-inch wrapped-and-re-routed lines from the tank to the pump, stock
diameter (not sure of dimension) wrapped lines from the pump to the
carb and STOCK AND UNWRAPPED return lines.
I'll check the diameter of the line from the pump to the carb but I'm
confident that isn't the problem. I'll be really perplexed if the
problem turns out to be the return line diameter! I mean, the exit
tube from the pump is, at the most, 1/4-inch diameter. But I'll go
ahead and fix that up with the wrapped 3/8th as well. We're both
running 7 to 8 psi right now. If the return line doesn't solve the
problem, I'll try the same type of pump you're running. Perhaps the
return outlet nozzle diameter on your pump is 3/8-inch.
One more thing: I've got some "thermal stickers" that I'm going to
(temporarily) gob all over the engine and engine compartment to map
out the the temperatures. That may also help answer some questions.
Will let you know (next summer) if I solve this problem!
|
| 123.6 | electric better than mechanical | POLAR::PORTEOUSK | | Wed Jun 29 1994 18:46 | 25 |
| Hi guys:
In reponse to your questions about mechanical vs electrical,I
would have to go with the electrical pump.
I used to have a mechanical high performace pump made by Holley and
all I would get is vapour lock whenever it got hot out,and also
underhood temp at the carb were quite high.
So I put on a Carter High Performace electrical with built in
regulator valve set at 8 psi with new 1/2 inch lines running from
front to rear on the right side instead of drivers side to stay away
from heat(headers)and wrapped the complete line to keep it as cool as
possible.
The place were I mounted it is about 2 inches from the fuel tank onto
the floor of the trunk(there is just enough space).
This procedure cured all my vapour lock plus keeps my fuel delivery
as cool as possible. In reply to electricity and gas not mixing I
guess your correct but the gas and current does not see each other
at all as I have been running this combination on a 1980 Grand Prix
with 1972 455 for 2 years and have not had a fire (touch wood) at all.
The Carter pump cost 100 dollars up here in Canada and should be
cheaper down in the States,so price wise they are pretty close,and
you don't have a shaft wearing out your cam!!!!
Ken
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| 123.7 | Wire it with an eye towards safety. | VMSNET::M_MACIOLEK | Four54 Camaro/Only way to fly | Wed Jun 29 1994 22:06 | 5 |
| I run both Electric and mechanical pumps on my Z28. The only thing
I'd add to .6 is to make sure you have some form of electrical kill
switch in your car. If the engine isn't running, neither should
the pump. If you were in a wreck and your pump were to still be
pumping fuel you quite possibly could become extra-crispy.
|
| 123.8 | GM fuel pump switch from a 'vette will work fine | USHS01::HARDMAN | Massive Action = Massive Results | Wed Jun 29 1994 23:01 | 15 |
| The kill switch should be easy. GM uses an oil pressure sending switch
on their EFI cars that will turn the pump off at anything less than 3-4
psi. You could wire that switch into your fuel pump circuit (via a
relay). When the engine stops, the pressure drops and the pump shuts
down.
On EFI cars, you need pressure instantly to feed the injectors. The
computer bypasses the oil switch during cranking to eliminate this
problem. You shouldn't have any problem with a carb though. You've got
that toilet tank, er, float bowl full of gas that should do you just
fine until the pressure comes up. ;-) If really needed, you could
easily add a momentary switch to engage the pump while cranking.
Harry
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| 123.9 | Kill Switch | POLAR::PORTEOUSK | | Thu Jun 30 1994 15:30 | 8 |
| In reply to .7 I forgot to add that I do have a kill switch mounted
in between the pump and the power source,this switch cost $2.00 as
it is a simple toggle switch with a 20 amp relay built in.
As I have power windows and was a real pain whenever you went to
roll down the windows the fuel pump would come on,as I agree that
safety should be #1 then SPEED.
Ken
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| 123.10 | | CXCAD::C_WILLIAMS | Hammer | Tue Jul 05 1994 11:37 | 26 |
|
I've been told by a couple of people to run a high-po mechanical pump
backed by an electrical. I am assuming that the electrical would keep
a constant supply (via pressure or volume) of fuel supply behind the
mechanical. Yet at the same time, I've seen and heard of people
running the electrical through the mechanical pump by taking the cam/
fuel pump eccentric off.
The stock mechanical pump on my '67 Firebird is 6.5 PSI. I don't know
the GPH, however. HO in California suggests running a 7 PSI electrical
backer. Again, I don't know the GPH of this pump though. What do I
actually gain in doing this? Instead of pulling the fuel, I'm now
pushing it. But I should still have the same PSI, right?
Right now I'm planning on just popping in the electrical and keeping my
mechanical running as well. I'll see if that helps.
As I previously stated, I have run 3/8" line. It's entirely wrapped
and away from all heat sources. I have also wrapped the line going
from the mechanical pump to the carb.
Also, is there a way to hook up the electrical pump to the ignition?
Carl.
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| 123.11 | | CXCAD::C_WILLIAMS | Hammer | Tue Jul 05 1994 11:45 | 7 |
|
If it's vapor locking somewhere between the tank and the pump, I would
understand the need for an electrical closer to the tank. As the
chances of negative pressures/cavitation in the line would be less when
it is being pushed than pulled. Especially if you have too tight of a
seal on the gas tank cap and are creating a vacuum inside the tank.
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| 123.12 | Where ? | CMOTEC::JASPER | Stuck on the Flypaper of Life | Wed Jul 20 1994 07:27 | 25 |
| So, to recap for the ignorant (me), if I add an electrical pump between
the tank & the mechanical pump, the mechanical pump will
1. Regulate the pressure to the Carb.
2. Allow fuel to flow through the Mechanical pump when the engine is
idle to prime the float bowl. Priming the carb is something I need as
my 302 has to start quickly.
The unknown is will the mechanical pump suck fuel through the
electrical pump ?
Also, what is the best height to mount the electrical pump ?
Multiple choice : Same level as the fuel in the tank ?
Same level as the Mech Pump ?
Same level as the Carb ?
Something else ?
Where does vapour-locking occur ?
Is it in the pressure section between the pump & carb ?
vaccuum section between the tank & the pump ?
both of the above ?
My car has a rear-mounted Ford 302 with 4 barrel Holley Mech.2ndary.
As the engine is out of the airflow at low speed, it will get HOT~~~.
Tony.
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| 123.13 | electric pumps | CSLALL::NASEAM::READIO | A Smith & Wesson beats four aces, Tow trucks beat Chapman Locks | Wed Jul 20 1994 12:15 | 65 |
| > 1. Regulate the pressure to the Carb.
No, fuel will simply flow through the mechanical pump at the pressure of
the electric pump.
The "regulation" of the mechanical pump as simply it's maximum achievable
output. If the electric's output is higher, it'll be present throughout
the system. The flow might be reduced a bit due to the size of the
mechanical pump's lines, but the pressure will be that of the electric
(provided it's higher than the mechanical)
The electric, when assisting the mechanical, can help the mechanical
produce *more* pressure than it would had it been simply been "sucking" the
fuel out of the tank.
The electric, if it's mounted next to the tank, preferably near or below
the bottom of the tank, will be gravity-fed and will eliminate any vapor
lock situations PROVIDED THE FUEL IN THE TANK STAYS COOL. If the fuel in
the tank gets hot even the electric pump will have trouble pumping it at
the pump's rated pressure.
> 2. Allow fuel to flow through the Mechanical pump when the engine is
> idle to prime the float bowl. Priming the carb is something I need as
> my 302 has to start quickly.
Yes, it'll prime the carb because it'll force fuel through both of the
mechanical pump's check valves. The mechanical pump is simply a diaphragm
that moves up (sucks fuel in through the input check valve while sucking
the output check valve closed) and then down (forcing the output check
valve open and the input check valve closed). The check valves are usually
just rubber (Buna, maybe Viton) discs.
> The unknown is will the mechanical pump suck fuel through the
> electrical pump ?
Depends on the type of electric pump. Diaphragm pumps, yes. Vane pumps,
probably not.
> Also, what is the best height to mount the electrical pump ?
> Multiple choice : Same level as the fuel in the tank ?
> Same level as the Mech Pump ?
> Same level as the Carb ?
> Something else ?
at or near the bottom of the tank and as close to the tank as possible.
Your goal is to eliminate as much of the vacuum requirements as possible.
It's a lot easier to deliver fuel under pressure than it is to suck hot,
boiling fuel.
> Where does vapour-locking occur ?
> Is it in the pressure section between the pump & carb ?
> vaccuum section between the tank & the pump ?
> both of the above ?
Wherever the fuel is allowed to boil. Could even happen in the tank if the
exhaust runs under the tank.
> My car has a rear-mounted Ford 302 with 4 barrel Holley Mech.2ndary.
> As the engine is out of the airflow at low speed, it will get HOT~~~.
Where's the tank?
A fuel line cooler might help if you can get it into the airstream.
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| 123.14 | Fuel cooler ? | CMOTEC::JASPER | Stuck on the Flypaper of Life | Tue Jul 26 1994 06:36 | 8 |
| There are 2 tanks, 1 in each doorsill (under the doors). There may be
some radiator heat output billowing under the car, but the tanks are
well away from exhaust & engine heat.
A Fuel line cooler seems a good idea though. I've never seen one, is
this a passive metal pipe section with cooling fins ?
Tony.
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