Hard start
 

On my 72 gm 350 after it sits for about a month it is hard to start. It does have a mechanical fuel pump. Is it wise to dump a little gas down the carb to help it along?

Re: Hard start
 

If you did that, I am sure it would fire right up. Mine is a right leg workout of small weight, many reps if it sits for a month

Re: Hard start
 

A shot of gas will help it fire up and it may keep running or not. One of my projects takes a few tries to get it to the point of it supplying its own gas. This tactic, IMO, saves some wear and tear on the starter.

Just be aware that this approach can cause some potential problems like spilled or leaked gas. If backfiring occurs along with spilled or excessive gas...a fire is possible. It is wise to pour the shot into the primaries, not the secondaries. This will help ensure the shot does not set on top of the butterflies and try to leak out the shaft holes in the sides or drop all the gas into the intake at the slight push of the pedal.

Re: Hard start
 

I keep a small catsup squirt bottle to squirt gas in . No spills and you have control of the amount you use

Re: Hard start
 

Better to use small funnel or the ketchup bottle to fill the float bowl through the vent. A couple of ounces is all that is needed. Much safer than pouring fuel in the bores and less chance of flooding the engine.

Allow the engne to sit for 5 minutes or so after filling the float bowl to allow the accelerator pump to absorb fuel and swell up. Then the accelerator pump is more likely to work correctly.

If you have no other option but to pour fuel in the bores then make sure you hold the butterflies open so the fuel doesn't run out the butterfly shafts.


And always put the air cleaner back on before cranking the engine to prevent a fire.

Re: Hard start
 

A shot of brake cleaner in the snorkel will do the same for you. You could use ether, but it's harder on the engine.

Re: Hard start
 

I keep a quart of the 50:1 TruFuel weed-whacker fuel on hand. When a vehicle has sat for a few weeks I remove the air cleaner, dump a cap full of the TruFuel in and crank. Usually have to dump in one more cap and then it will idle. Saves a lot of wear and tear on the starter. And since the TruFuel is a premix it provides some top end lubricant to help with the overly rich temporary mixture.

Re: Hard start
 

I stumbled onto a possible solution for this for those running the Q-jet. There are fuel filters that have a check valve in them to prevent the fuel from running down back back out of the carb and into the mechanical fuel pump.

https://quadrajetparts.com/short-pap...alve-p-79.html

Re: Hard start
 

Law of Physics: liquid cannot run up hill.. The needle and seat is located slightly above the fuel level in the carb bowl and well above the bottom of the bowl.. If fuel is leaving the bowl not through evaporation, it's because the metering well plugs are leaking..

Re: Hard start
 

Yes, physics involved and agree about meeting wells. Check valve would leave fuel in the filter housing and likely in the fuel line between pump and carb due to the physics of a vacuum when the check valve is closed. Being closed and less exposed to atmosphere, less ability for what fuel is there to be lost due to evaporation. Certainly slower to evaporate.

I suppose there was a reason for the check valves.