Electric pump before or after mechanical

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swies

swies

Wish I had more time.
Joined
Apr 27, 2015
Messages
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Location
Wa State
318 +.030
Zero decked
KB167
RPM AG
Eddy 1405 W/ 1” phenolic
Eddy mech fuel pump
Stainless fuel line insulated in the entire engine compartment

I suffer from the warm start issues and when I open good, my fuel pressure gauge shows 0 and the bowls are empty.
I have read on this site about installing lv/lp electric to help with this issue but cannot find it now.
Do I install it before the mechanical or after?

Thanks to you guys for the help!
 
Best is just a good electric pump with a bypass, a line back to the tank. Will never do that again. I just used a fuel filter designed with a third port, back to tank, via a new steel line. You can buy a fuel tank float/sender with the a second port on it for a return line. Block off the mechanical pump.
 
And the pump not in the engine compartment. As close to the tank as you can get it. This is what I used on my 66,
Mallory Comp Pump Fuel Pumps 29259

20170128_7.jpg
 
just run a return line and keep the mechanical pump
there is no need for an electrical in your situation

you are sure the fuel is evaporating right?
the car fires up just fine in the mornings?
 
Electric pump INSTEAD of mechanical, if you just GOT TO run an electric. .
 
I am sure it is evaporating. After investigating, I noticed the pressure gauge shows nada. Pull the Carb top and the bowls are empty. Crank, crank, crank (5-10 secs) pressure comes up, 10 seconds later it fires.
I have checked backflow and cant find any. I believe when I shut down, the fuel in Carb evaporates, needle/seat opens, pressure bleeds into bowls and then evaps some more.
Not sure this is what’s happening, just what I have concluded from inspection/investigation.
I don’t really want to run an electric but not sure what to do about the issue.
Not going to buy a new tank for a return line. Mine already has the charcoal can return capped that I could use but what would that help? Won’t stop the pressure loss will it?
 
Last edited:
swies said:
I am sure it is evaporating. After investigating, I noticed the pressure gauge shows nada. Pull the Carb top and the bowls are empty. Crank, crank, crank (5-10 secs) pressure comes up, 10 seconds later it fires.
I have checked backflow and cant find any. I believe when I shut down, the fuel in Carb evaporates, needle/seat opens, pressure bleeds into bowls and then evaps some more.
Not sure this is what’s happening, just what I have concluded from inspection/investigation.
I don’t really want to run an electric but not sure what to do about the issue.
Not going to buy a new tank for a return line. Mine already has the charcoal can return capped that I could use but what would that help? Won’t stop the pressure loss will it?
Click to expand...
Not a tank this.....http://www.jegs.com/i/Auto-Metal-Direct/106/881-1468-3R/10002/-1?CAWELAID=230006180013542138&CAGPSPN=pla&CAAGID=44693592161&CATCI=pla-172937246471&CATARGETID=230006180039218457&cadevice=c&gclid=EAIaIQobChMIpYuGyIaT2gIVE1p-Ch3pHAVfEAQYBSABEgLywfD_BwE
 
You might also want to double check your float settings, if the float is set too low, the fuel will evaporate quicker.
 
The Edelbrock Performer 1404/1405 carb float bowls are known to evaporate dry after about 3 days of sitting. I have two of them, I looked into this problem and it seems to be a common problem. The bowl vents allow the fuel to evaporate right out of the bowl. Mine starts fine when warm, but after it has been shut down for 3+ days it takes a lot of cranking for the mechanical fuel pump to refill the float bowls. I'm going to install an electric fuel pump to get around this problem. Meanwhile, to avoid excessive cranking after the engine has sat for 3+ days, I bought a large 100cc syringe off ebay, remove the air cleaners, and squirt 40cc of gas through each bowl vent into the float bowl, then she fires right up every time.
edelbrock vents.JPG
 
swies said:
318 +.030
Zero decked
KB167
RPM AG
Eddy 1405 W/ 1” phenolic
Eddy mech fuel pump
Stainless fuel line insulated in the entire engine compartment

I suffer from the warm start issues and when I open good, my fuel pressure gauge shows 0 and the bowls are empty.
I have read on this site about installing lv/lp electric to help with this issue but cannot find it now.
Do I install it before the mechanical or after?

Thanks to you guys for the help!
Click to expand...
Before the pump and as close to tank as you can. If your diaphragm fails it is possible for the electric pump to fill the crankcase with fuel. Use it to prime and start, then shut it off and the mechanical pump will pull fuel through the electric pump.
Airtex External Electric Fuel Pumps E8012S
 
Problem stems from modern gas. Old fuel had stabilizers in it because everyone had a vented fuel system. Now cars have a sealed system and fuel injection. I was first made aware of this by Herb Macandless (sp?) at a clinic at Carlisle. Per his instructions a small impeller electric pump that the mechanical fuel pump can pull through is the ticket. I only use the electric pump to prime the carb and then turn it off. Has worked great on 2 street cars for 5 years now.
 
Smartest thing I did (before I went EFI!!) was a rear mount electric pump and a home built return system with a wix filter....built in return port. They make several sizes. AND a nice big thick carb isolator gasket.

The thing is if you PUSH the fuel to the front UNDER PRESSURE it raises the boiling point in exactly the same way a rad pressure cap raised the boiling point of coolant.

"You could" also run the electric pump (in the REAR) INTO the mechanical. When a mechanical pump reaches design pressure, the arm just floats on the cam, so it will not "add" any to the pressure already crated, unless it drops for some reason.

THE PROBLEM is that if the pump diaphragm leaks/ ruptures, the electric pump will REALLY fill up the crankcase with fuel. "Rapid expansions" sometimes occur.
 
I don't understand any of this? I have a 1406 on my truck and I let it set for a week at a time or more and give it 2 pumps and crank it over with a mechanical stock pump and no problem?
 
^^^and again that was the 1 my Chevy friend gave me for free because it got a little stiff at 3/4 throttle? LOL He bought a new Edelbrock to solve the problem and now the truck got worse and he doesn't drive it no more LOL
 
Is there any possibility you could just have a bad mechanical fuel pump and need a new mechanical fuel pump? Did you cover that I can't remember?
 
swies said:
318 +.030
Zero decked
KB167
RPM AG
Eddy 1405 W/ 1” phenolic
Eddy mech fuel pump
Stainless fuel line insulated in the entire engine compartment

I suffer from the warm start issues and when I open good, my fuel pressure gauge shows 0 and the bowls are empty.
I have read on this site about installing lv/lp electric to help with this issue but cannot find it now.
Do I install it before the mechanical or after?

Thanks to you guys for the help!
Click to expand...

In answer to ur question, put it at the back , behind the tank if possible, use it as a pusher .
 
Buddy just installed a backup fuel pump,runs 2 electrics insead of a mechanical. Uses check valves to prevent back flow.
I would run a pump and check valves T’d around mechanical pump. As a prime/backup. This could be used if mech pump fails.
 
j par said:
Is there any possibility you could just have a bad mechanical fuel pump and need a new mechanical fuel pump? Did you cover that I can't remember?
Click to expand...
I have checked the pump repeatedly. It is an Edelbrock 1720 and the check valves will hold for days.
RustyRatRod said:
Electric pump INSTEAD of mechanical, if you just GOT TO run an electric. .
Click to expand...
I don't HAVE to go electric. I am just thinking the electric will 'prime' the carb when I do want to start it after 3+ days. By using the lp/lv pump, it won't over pressure the needle valve but will 'charge' the fuel line prior to starting.
Sean
 
j par said:
I don't understand any of this? I have a 1406 on my truck and I let it set for a week at a time or more and give it 2 pumps and crank it over with a mechanical stock pump and no problem?
Click to expand...

How much ethanol is in your fuel?
 
Well I've done everything wrong so at least you know someone is backwards. I've never ran a return line number one. Last year's I ran a summit electric fuel pump that was extremely loud with a fuel regulator and brought the pressure down to 5 lb? Is there a return line needed when you can already make all the resistance you want? And now I put one of those little red Edelbrock pumps in the motor compartment! And it's supposed to love to deliver five to seven pounds and I have Edelbrock carburetors I've experience no problem? And still no return lines? Now everybody can jump on here and freak out about it?
 
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