Carb won't stay primed

[57larry]

got a Chevy 350 with an Edelbrock carb #1406 which was rebuilt. the block is a 91 which doesn't have a hole for a mech fuel pump. it's running a new blue Holley elect fuel pump. the engine runs like Jack the bear if you spray starting fluid in it.

once the engine sits overnight, it will not start. the rebuild kit had a new accelerator pump

I'm out of ideas. help please, thanks, Larry

[enjenjo]

Does the fuel pump have an oil pressure cut off switch?

[57larry]

no it doesn't, Frank

[kb426]

All I can offer is tomorrow before starting, look done in the carb and open the throttle and see if the pump is working. If it doesn't you know where to look. If it does, I'd pick on the choke next.

[sirstude]

Don't know if it helps, but on my Impala I am running an 870 Holley with a Holley red pump.  Will not start unless I run the pump for a minute and then hit the throttle twice.  Works great then.

Doug

[enjenjo]

no it doesn't, Frank

Okay, I believe you are loosing your prime. Try running the pump for 20 or 30 seconds before you turn it over.  You can also install a fuel filter with a check valve built into it. Edelbrock carbs in particular are famous for this.

[57larry]

I too believe it's losing it's prime. where can I buy a fuel filer with a check valve in it. thanks for your help Frank

[kb426]

Are you guys thinking it can suck all the fuel out of the bowl after sitting? I know several people with carbs and they all think that it's because of the ethanol evaporating way before the gasoline. AFB's didn't do this in my exp. and this is what the Edelbrock is based on. What is different?

[enjenjo]

Are you guys thinking it can suck all the fuel out of the bowl after sitting? I know several people with carbs and they all think that it's because of the ethanol evaporating way before the gasoline. AFB's didn't do this in my exp. and this is what the Edelbrock is based on. What is different?

In a word, no I don't think it's sucking the fuel out of the bowl. I think there may be some evaporation going on when the engine is shut off, but I think there is some way that the fuel is leaking out of the bowl. The only mechanism I can see that would allow this is the metering rods.

The fuel in the line though can run back to the tank, so the lack of fuel in the bowl, and the time it takes for the fuel to purge the air from the line and reach the carburetor to refill it seems to be the problem.

I have owned several cars with Edelbrock carburetors on them, and all of them have done it to one extent or another. My Marlin with dual Edelbrocks takes 20 to 30 seconds of cranking, and lots of pedal pumping to start after it has set for several days.  A bit less setting over night. Setting for an hour or two, it will start without touching the gas pedal on the first turn.

Do a Google search for fuel filter with a check valve, and several come up.

[Crosley.In.AZ]

My 1961 Dodge Lancer with a Edelbrock carb, same problem if the car sat for more than 1 day.

[wayne petty]

lets do some diagnostics..

disconnect the fuel line to the carb... blow into it..  if you can blow bubbles in the fuel tank.. you have an issue with the system not holding pressure..

instructions from holley on installing or cleaning the fuel pump bypass plunger/check valve assembly.

http://documents.holley.com/199r7926.pdf

a video showing some of how the plunger works..

please run a 10 micron fuel filter before these pumps..  magnets in the fuel tank also..

as the fuel pump builds pressure.. it pushes the plunger back to keep the pressure stable.. any additional fuel pumped is dumped back into the inlet side of the pump cavity.  

if the plunger sticks closed. the fuel pressure will be too much.. causing flooding..

if the plunger sticks open.. and this happens more often.. you will usually hear the pump spin faster as the pressure is lost about 10 or 15 seconds depending on engine speed before the carb runs out of fuel.

don't sand the plunger.. if there are burrs.. use a fine diamond file..  even a diamond nail file just to take the burr off.

use ONLY NYLON BRISTLE TUBE BRUSHES to clean the plunger and spring bore..  do not go in with brass , steel or stainless steel brushes. they will damage the bore and ruin your pump ..

say this is new.. http://www.harborfreight.com/Engine-Brush-Kit-20-Pc-69020.html

i had not seen that before..  this is what i was going to link

http://www.harborfreight.com/9-piece-tube-pipe-nylon-brush-set-90631.html

this might be a solution..  after the filter.. before the pump.. so the prime is NOT lost out of the pump when sitting.. the earls version is for AN10 size.. others are available.

https://www.holley.com/products/plumbing_an_fittings_and_hose/adapters/valves/one_way/parts/251010ERL

these you can sometimes order thru local parts stores.

Airtex CV8000 Fuel Flow Check Valve

Russell 650603 Black Anodize Check Valve (6an Male to 6an Male)


you can also... since many of you will be converting to an oil pressure controlled fuel pump circuit..   install one of those latch safety covers and either a momentary toggle or momentary push button to allow you to operate the fuel pump to pull fuel up and out of the tank.. filling the pump and eventually filling the float bowls.

hope this helps.. i have been dealing with sediment in fuel systems since 1983 ..  a friend with a blue pump on his dodge motor home to reduce vapor lock and stalling issues continued to have stalling issues.  instead of causing a restriction in the line.. holley who actually was his sponsor sent him another .. he installed a pair of the blue pumps in parallel.  i could stand in the steps and listen to the one fuel pump speed up.. then the other would speed up and the engine would die a 10 seconds later. holley tech finally said.. here put one of these Fram HPG-1 filters on before the pumps.. end of the issue..  the sediment from the tanks were holding the plunger open and dumping the output of the pump back into the inlet cavity...  this reduced suction built by the pump to zero..

[57larry]

thank you everybody for the help. Larry

[papastoyss]

Are you guys thinking it can suck all the fuel out of the bowl after sitting? I know several people with carbs and they all think that it's because of the ethanol evaporating way before the gasoline. AFB's didn't do this in my exp. and this is what the Edelbrock is based on. What is different?

Back in the AFB days we didn't have the ethanol laced fuel we have today. I've used the Edelbrock carb several times & had good results w/installing a 1"phenolic spacer/heat shield between the carb & intake along w/an aluminum heat shield. Before trying this I've shut the engine off , raised the hood & actually heard the gas boiling in the carb.

[Arnold]

Mid 70's 440's the interface warped(not sure if it was the bowl or the a/h) between the bowl and the airhorn..warping it..leaking fuel..rough rich idle empty bowls etc. There was a tsb. Suggestions of extra thick gaskets.
At first they only do it when hot..or they feel like it. Sometimes they just warped and were junk..others..getting the screws out nice..and torqued back in maybe with a thicker gasket.

[Mikej]

Try a Holley.