Fuel pressure problem

[EDMOPAR]

Hi, have any of you had this issue, the setup is a 340--1406 edelbrock--fuel filter--regulator/guage--mechanical pump--the fuel pressure is set at 5.5 psi and the car runs fine--the problem is when you turn the car off the fuel pressure goes down to zero within an hour--not holding pressure--is this most likely a fuel pump issue?--I thought they had a check valve--any help appreciated,ps all of these parts are new, Ed

 

[clinteg]

That is completely normal as far as I know. I've had mechanical and electrical pumps and they dropped to zero almost immediately after shutdown. As long as you're not dropping pressure as throttle, what's your concern exactly?

 

[TrailBeast]

That is completely normal as far as I know. I've had mechanical and electrical pumps and they dropped to zero almost immediately after shutdown. As long as you're not dropping pressure as throttle, what's your concern exactly?

This is correct.
The fuel pressure will drop immediately and is normal.
They don't and never did have an antidrainback in these systems, and an electric fuel pump gets rid of all the related problems anyway.

 

[EDMOPAR]

That is completely normal as far as I know. I've had mechanical and electrical pumps and they dropped to zero almost immediately after shutdown. As long as you're not dropping pressure as throttle, what's your concern exactly?

After the car sets up for a day or two it is hard to crank because the fuel has drained from the carb. Don't remember my other 340 being this way but I did have an electric fuel pump at the tank

 

[clinteg]

After the car sets up for a day or two it is hard to crank because the fuel has drained from the carb. Don't remember my other 340 being this way but I did have an electric fuel pump at the tank

If you have fuel draining from your carb, there must be other issues going on. Just to clarify, when you say hard to crank, are saying that the motor is literally hard for the starter to crank the motor or it's hard to get started due to lack of fuel?

Between the electrical and mechanical fuel pump on my 950HP, the engine started faster with the mechanical. I can't expain that but changing between the two and changing nothing on the carb, the electric pump takes a few extra cranks. After sitting a few days, I'd crank a bit, pump pump pump, and then the engine would immediately fire on the next crank with the mech pump.

 

[EDMOPAR]

If you have fuel draining from your carb, there must be other issues going on. Just to clarify, when you say hard to crank, are saying that the motor is literally hard for the starter to crank the motor or it's hard to get started due to lack of fuel?

Between the electrical and mechanical fuel pump on my 950HP, the engine started faster with the mechanical. I can't expain that but changing between the two and changing nothing on the carb, the electric pump takes a few extra cranks. After sitting a few days, I'd crank a bit, pump pump pump, and then the engine would immediately fire on the next crank with the mech pump.

motor is hard to start because fuel is not getting to engine, lack of fuel, have to crank and pump accelerator in order to get it started, its like the fuel is draining back to the tank when car is setting, I don't have the car completed so I have not drove the car except in the yard, I do have the tank vented, could this be the reason why,thanks

 

[clinteg]

motor is hard to start because fuel is not getting to engine, lack of fuel, have to crank and pump accelerator in order to get it started, its like the fuel is draining back to the tank when car is setting, I don't have the car completed so I have not drove the car except in the yard, I do have the tank vented, could this be the reason why,thanks

Maybe some things to start looking at or give us more info on:

-Is the fuel pump new or old? I assume new b/c you've said you changed it. It's possible it is not functioning properly?
-Check and see (pull a drain plug or such) to see if there is any fuel in the bowl after a couple days sitting. Then start it, shut down, drain again, and compare how much fuel you get to before.
-What do you have your timing set at?
-The tank must be vented. It should have no effect on what's going on in the carb bowls.
-I'm not familiar with your carb but maybe someone else will know. Shouldn't there be a needle/seat or something inside the carb that keeps the fuel from returning back through the line?

 

[TrailBeast]

If you have fuel draining from your carb, there must be other issues going on. Just to clarify, when you say hard to crank, are saying that the motor is literally hard for the starter to crank the motor or it's hard to get started due to lack of fuel?

Between the electrical and mechanical fuel pump on my 950HP, the engine started faster with the mechanical. I can't expain that but changing between the two and changing nothing on the carb, the electric pump takes a few extra cranks. After sitting a few days, I'd crank a bit, pump pump pump, and then the engine would immediately fire on the next crank with the mech pump.

By the time the engine has cooled from being driven half the fuel in an Edelbrock has already evaporated.
Add that to the fuel running back to the tank from the line and it does create a fuel availability issue.
I think most of us that run Eddies deal with some of the exact same problems, along with the engine running like crap for a min or two after it has sat for 10-15 min and is restarted.
We also have to remember that once the fuel is in the bowls it is physically impossible for it to get "sucked back out" so it has to be evaporating.
Taking all this into account, it should only take about 3-5 seconds for the line and bowls to refill and the car should then start right up.
More than that and there is a problem, so this is one of the main reasons I changed to an inline electric pump.
That solved that, and my car fires up almost faster than you can let go of the key.
For people that want to use a mechanical pump and an Eddie carb, it seems they pretty much have to put up with that.

Just what I have seen anyway.