340 takes a long time to start

[RamRod]

Hi everyone. This forum has been a great place and has helped me out a ton. I have another stumper for everyone.

I have a 1970 340, which takes a long time to start. Every day, the Carberator bowl is empty. I had it running yesterday, but today it was completely empty again. I do not smell raw gas in the garage, so I don't think that it is evaporating or leaking anywhere. I had another carb that I put on, because I thought that the carb was leaking somewhere, but I have the same thing happening. So I don't think that it is the carb. Could it be the fuel pump?

Thanks,
RamRod

 

[Chryco Psycho]

It is evaporating , fuel is not the same as it was years ago .
I would recommend blocking the heat cross over through the intake & you can use a thin isolator like Coolcarb sells to drop the temp 75* or more in the carb .

 

[Chryco Psycho]

You could add an electric fuel pump to fill the carb before you try to start it .

 

[RamRod]

I thought about the electrical fuel pump, but I want to keep the car as close to stock as possible. Where would it be evaporating from? Isn't the fuel bowl a closed system?

 

[toolmanmike]

Nope, it evaporates out of the bowl vents. I shut mine off and with a hot engine (called heat soak) you can hear the fuel boiling in the carb. The puppy pee gas we have nowadays boils at a fairly low temp. A fuel filter with a return line helps while the engine is running but what happens after you shut the engine off is hard to stop. A thick carb base gasket helps. Carter/Edelbrock are more susceptible because the float bowls are directly above the intake and carb base. Holley's are much better because of their overhanging float bowls on many of their models. Like CP suggested, a electric priming pump can work wonders. Let me find a popular number and I will repost it. A momentary pushbutton switch works well and can be hidden under the dash or in the ash tray or glove compartment.

 

[toolmanmike]

A little pump like this would work fine. The mechanical pump will pull fuel through this one when it's not running.

Airtex External Electric Fuel Pumps E8012S

Find Airtex External Electric Fuel Pumps E8012S and get Free Shipping on Orders Over $99 at Summit Racing! Airtex external electric fuel pumps are precision-machined to maintain accurate metering for reliable fuel delivery. The auto industry leader in fuel delivery products, Airtex covers more...

www.summitracing.com

 

[RamRod]

Thanks. Can I run it online with the other? Series? Or does it need its own line?

 

[toolmanmike]

Thanks. Can I run it online with the other? Series? Or does it need its own line?

Yes in series and you run it in addition to your mechanical pump. The electric is just used to fill the carb up after the fuel evaporates. Just a momentary switch so it doesn't run constantly.

 

[toolmanmike]

Here is a good thread on FABO you may want to read. Losing Fuel

Losing Fuel

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...

www.forabodiesonly.com

 

[Chryco Psycho]

You can also switch to EFI , Fitech & Fast are around $1000 & then you do have a sealed fuel system

 

[toolmanmike]

You can also switch to EFI , Fitech & Fast are around $1000 & then you do have a sealed fuel system

That has it's own issues.

 

[Chryco Psycho]

Yes it does but the fuel system is sealed so no more evaporation & starting is easier .

 

[CMC]

What issues have you seen with EFI?

 

[k2steve]

What issues have you seen with EFI?

The biggest problem I had was a clean 12v power supply, my battery is in the trunk. I finally run a dedicated line and a switch under the dash as a last resort to get the Fitech to work halfway right.
My trouble was hot starts(flooding). It fixed that and the idle speeds for the AC on/off.

 

[CMC]

Yes, hot starts. we solved that issue with a new coil...

Purrs like a kitten now, hot or cold.

 

[i_taz]

You want stockish...Thermoquad's came on 340's...

 

[Chryco Psycho]

In the earlier days I have seen a number of EFI controllers die , I have seen fuel pump inlets get clogged so the tank has to be clean , longevity can be a problem with some of the cheaper systems . sensors fail even on factory EFI systems .

 

[RamRod]

Thanks everyone for the suggestions. I put the inline electric pump in the other day. Picked one up from NAPA and put it in, and got the switch under the dash. Now all I have to do is prime the carb for 2-3 seconds, pump the pedal twice and it fires off right away. Works great now.

 

[RamRod]

You want stockish...Thermoquad's came on 340's...

I'd double-check that. I am pretty sure that it is a Carter AVS, if I remember right I think that the number is 3933 or 3934 depending on auto or manual.

 

[Scoop]

Hello. I have a 74 Challenger with a 340. It was very hard to start when cold. Not as bad when warmed up but still. I would have to pump the gas 7 to 10 times to get it going. Not knowing when the last time it was tuned up, and I figured the distributor was original. I got a distributor kit from Summit Racing, that included the coil, ballast and electronic module and wiring. My mechanic installed it just last week. What a difference. If fires right up now and sounds even better. I hope that helps and that you find a fix.