Losing Fuel

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512Stroker

512Stroker

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After the car is parked for several days I have a hard time getting it to start - like no fuel.
After I crank it for a while and pump the snot out of it it will fire and run normal. Somehow it is losing fuel.
I am running an LA340 with Edelbrock 1408 carb with electric choke which is working and a Edelbrock mechanical fuel pump.
All appears normal and it only does it after it sits for several days.
No hot start issues
No run issues
No gas in the oil
No fuel on the ground
No leaks that I can find anywhere in the fuel system
I dont believe it is boiling out of the carb I use a thermal spacer between the car and manifold to prevent this.
Is there any way it can siphon back to the tank?
Im lost
 
Before trying to start it after it having sat for a few days, pull the air filter off and work the throttle to see if the accelerator pump is working.
If not, the carb is either empty or the pump plunger is dried up.

Without pumping the throttle, crank the motor over for like 10-15 seconds to fill the bowls.
Again check to see if the accelerator pump is working.
If it works right away, then the carb was likely empty.
Most likely from evaporation.

At that point, you should be able to give it a few pumps, and it should start right up.
 
this is a common problem with the new gas it evoperates out of the carb it is normal thing to happen when our cars sit for a while if you pour a little gas in the carb before up try to start it its work well or most of us in the local car club spray stating fluid in the air cleaner be for we start the motor
 
AJ/FormS said:
If you have a Holley, check the intake for fuelstains underneath the pump
Click to expand...
Eelbrock 800 cfm model 1408
Had many Holleys thru the years but I really like the tun-ability of the Edelbrock
Actually I like both
 
512Stroker said:
Eelbrock 800 cfm model 1408
Had many Holleys thru the years but I really like the tun-ability of the Edelbrock
Actually I like both
Click to expand...

You have 2 problems.
1. Edelbrocks DO evaporate empty after a couple of days. (Holleys don't)
2. You have a mechanical pump so it takes some cranking to get fuel back in the Edelbrock.
The insulator barely helps the problem on an Edelbrock.
(I have one as well and it barely made a difference.)

A full 3/8 circulating return fuel system didn't help either. (in hopes of cooler fuel at the carb)

People keep thinking fuel drains back, but it's not physically possible for the fuel to get sucked back out of the bowls.
That's what it would take for drainback to empty the carb and the engine not start. (can't happen)

I know what I'm telling you is true and fact, as I have been through it all myself.
Putting an electric pump on the car will fix the Edelbrock being empty at startup if you really want to keep it on there.
Running a Holley would make it so you don't need the electric pump.

I did run the Edelbrock for years with the electric pump and that worked well because turning on the key fills the fuel bowls back up before starting.
 
TrailBeast said:
People keep thinking fuel drains back, but it's not physically possible for the fuel to get sucked back out of the bowls.
That's what it would take for drainback to empty the carb and the engine not start. (can't happen)
Click to expand...

From the bowl I agree; the fuel cannot jump up to the valve. that's impossible.
 
But after the inlet-valve is open, atmosphere can get into the fuel line, and if a check valve is bad in the pump, then the fuel in the line can siphon back until equilibrium is reached.
Then on the restart, the pump has to either pull the fuel back up, or send it up, depending on where equilibrium was.

But another thing that can happen is this ; EFI cars do not need the VOCs nor a high vapor pressure, to be in the fuel, as the injectors do a pretty good job of prepping the fuel for ignition. So the powers that be, took a lot of the VOCs out so they could sell an inferior gas to the predominantly EFI cars out there. Plus in EFI cars the fuel sits in a closed system, until the car is started.
When our carbyed cars have to use the same fuel, first it sits in a vented tank, with the VOCs evaporating, which reduces the vapor pressure and "thickens" the fuel. Over time, and not much of it, the fuel becomes harder and harder to light off.
So even tho your bowl is half full, and in the old days, would only require a couple of pumpshots to get going; whereas now, you are trying to light the syrup....... if it even goes up the wells.
High cylinder pressure can ease the problem, by virtue of the fact that a good ring seal on a small chamber, "pulls" harder on the wells. And a proper choke setting is invaluable because the low pressure under it during cranking, causes the fuel to spew out of every possible place it can, short of the pump-circuit. Now it's up to the high cylinder pressure to bring the temp up during compression, and then an MS Ignition can come in handy, cuz if the first strike don't light it, maybe one of the following ones will .
If you are stuck with a low cylinder pressure, or less than stellar ring seal,then you can have these kinds of starting problems. I'm not saying this IS OP's problem. I am saying that it could be a contributing factor.

I know, I know; you may not need 11/1 and 180psi, but I gotta tell ya, my engine does and it burns 87E10 for 100% of the time.It is well able to fire up once a week, for a trip around the country, and it has no MS on it. But it does have the finest inductive coil I have ever had; the Big Yellow Square-top Accell SuperCoil. And, and,and it has a double pumper on it,lol.
So, you be the judge.

Here is an experiment for you; pour some fresh clear gas into a small diameter, open glass jar. Level the jar,mark the liquid level, and put it somewhere safe outside, not in the sun..... like under your hood,lol. Come back every two or three days and watch the transformation; the same thing is happening in your float bowl.
 
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Its the crap gas we have these days. Edelbrocks are terrible for this. I recently pulled my carb and turned it upside down to drain. I got about an ounce of what looked like ice tea. I had just ran the car about a week prior.
Even the non-ethanol gas has other crap blended with it such as naptha. Anyone else notice the black mold like stuff that grows around the fuel cap or anywhere this stuff vents?
On a side note there is one other common problem with edelbrocks that will cause really hard starting. Underneath the accelerator pump nozzle is a check ball. These like to stick. Pump your throttle and see if your getting anything after it sits overnight.
 
Edelbrocks have smaller fuel bowl then holley......Holley accelerator pump is on the bowl....Eddy is not..
 
My Demon with a Edelbrock has been sitting since November. It will start in 30 seconds when I get it out. 2 seconds thereafter. Why? Because even if it does "dry out" the pump is able to fill it immediately. If it has not leaked past check valve. 512 stroker, pinch off the fuel hose going into pump. Try that for diagnostic purposes.
 
512Stroker said:
After the car is parked for several days I have a hard time getting it to start - like no fuel.
After I crank it for a while and pump the snot out of it it will fire and run normal. Somehow it is losing fuel.
I am running an LA340 with Edelbrock 1408 carb with electric choke which is working and a Edelbrock mechanical fuel pump.
All appears normal and it only does it after it sits for several days.
No hot start issues
No run issues
No gas in the oil
No fuel on the ground
No leaks that I can find anywhere in the fuel system
I dont believe it is boiling out of the carb I use a thermal spacer between the car and manifold to prevent this.
Is there any way it can siphon back to the tank?
Im lost
Click to expand...

draining back to tank, either a check valve or elec booster pump will work for this ^^^^^^^^
 
TrailBeast said:
You have 2 problems.
1. Edelbrocks DO evaporate empty after a couple of days. (Holleys don't)
2. You have a mechanical pump so it takes some cranking to get fuel back in the Edelbrock.
The insulator barely helps the problem on an Edelbrock.
(I have one as well and it barely made a difference.)

A full 3/8 circulating return fuel system didn't help either. (in hopes of cooler fuel at the carb)

People keep thinking fuel drains back, but it's not physically possible for the fuel to get sucked back out of the bowls.
That's what it would take for drainback to empty the carb and the engine not start. (can't happen)

I know what I'm telling you is true and fact, as I have been through it all myself.
Putting an electric pump on the car will fix the Edelbrock being empty at startup if you really want to keep it on there.
Running a Holley would make it so you don't need the electric pump.

I did run the Edelbrock for years with the electric pump and that worked well because turning on the key fills the fuel bowls back up before starting.
Click to expand...

Trailbeast what size/ psi electric pump would you reccomend? Location? I have an original 500 cfm Carter (rebuilt about 10 years ago) and have this 24 hour window of easy start vs crank and crank if over that. Stock style mechanical fuel pump too.
 
drewmac said:
Trailbeast what size/ psi electric pump would you reccomend? Location? I have an original 500 cfm Carter (rebuilt about 10 years ago) and have this 24 hour window of easy start vs crank and crank if over that. Stock style mechanical fuel pump too.
Click to expand...

I used to run a Carter rotary vane electric and it was ok, but it died way too early in my opinion. (less than a year)
Now I run a 7-10lb. Holley at 38gph and it has been fine for a year so far.
One hell of a lot quieter too.
I use a restrictor in my return line to keep the feed pressure at around 6-7lbs.
 
TrailBeast said:
I used to run a Carter rotary vane electric and it was ok, but it died way too early in my opinion. (less than a year)
Now I run a 7-10lb. Holley at 38gph and it has been fine for a year so far.
One hell of a lot quieter too.
I use a restrictor in my return line to keep the feed pressure at around 6-7lbs.
Click to expand...
And you do this inline with an engine driven mechanical pump?
 
ELECTRIC fuel pump solves that problem , i let my car sit for weeks , hit the fuel pump switch for 10 seconds then start the car , works every time . before the pump I had trouble starting the car after it sat for afew days , new fuel sucks as well
 
Nat said:
ELECTRIC fuel pump solves that problem , i let my car sit for weeks , hit the fuel pump switch for 10 seconds then start the car , works every time . before the pump I had trouble starting the car after it sat for afew days , new fuel sucks as well
Click to expand...
Did you run the electric pump in conjunction with the mechanical pump? Or was it a stand alone electric fuel Pump?
 
512Stroker said:
Did you run the electric pump in conjunction with the mechanical pump? Or was it a stand alone electric fuel Pump?
Click to expand...
yes I run both, i turn off the electric once i'm running , unless i'm at the track then i keep it running
 
Nat said:
yes I run both, i turn off the electric once i'm running , unless i'm at the track then i keep it running
Click to expand...
Sweet
What electric pump are you running?
Did you apply a separate regulator?
 
512Stroker said:
And you do this inline with an engine driven mechanical pump?
Click to expand...

No, just the 38gph Holley.

The cam in my 5.9 is a custom regrind without the fuel pump snout on it.
I knew I would always run an electric so I opted out on the mechanical pump ability.
I do run an LA cover and water pump though.
 
You can run this electric pump to prime or leave it run all the time with a mechanical pump. Mechanical pump will pull fuel thru the electric. I ran this pump with a Carter M6720 mechanical pump and dead head regulator. Mount it on a rubber strap and the noise will be less. Electric pump was mounted above the passenger side shock and forward fuel tank area.
Carter P60430 Carter Inline Electric Fuel Pumps | Summit Racing
 
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