priming the fuel system

Usually it does, unless there is an air leak on the suction side.

John

Remove the filter and install a blank hose ... a filter before the pump is not a good idea ... a strainer maybe.

quote:

Originally posted by accobra:
Remove the filter and install a blank hose ... a filter before the pump is not a good idea ... a strainer maybe.

+1 on that. Never restrict the suction side of a pump. Always put the filters on the pressure side.

thanks for the info guys, however the car has always run that way, and runs well. My aircraft has two fuel pumps and three fuel filters, one of which is before any of the pumps. No problems ( that's a good thing). At any rate, the question was how to reprime the system now that it's totally dry...input appreciated as always though..

Make sure your tank is not plugged.

If you're using the OEM fuel pump suction line (which is too small in diameter by the way) it has a little nylon sock on the end that is known for becoming completely plugged. The usual remedy is to blow air backwards through the line, which blows the brittle nylon sock completely off the end of the tube and thereby resolves the problem; but it makes a fuel pump suction filter mandatory to replace the pump inlet filtering originally provided by the nylon sock. Fuel pump suction filters are usually recommended by all high performance pump manufacturers, with filtration in the 100 micron range.

If the level of fuel in the tank is very low, and the fuel pump inlet line is empty, it may be too much lift for the pump, or the pump is operating vapor locked. Raising the level of the fuel in the tank, or pre-filling the suction line may resolve the problem. Slightly pressurizing the fuel tank (blowing in the tank vent) may be another way to get the fuel flowing.

-G

The original fuel pick up metal tubing in the tank has a nasty habit of rusting through at about the level the fuel is kept at in the tank.

These are pin holes that are hard to find or even see some times.

The lines are steel, so they have a clock running on them as to when they will do this, but it seems they all will eventually.

The significance to this is that if you had a pin hole at around 1/2 tank, if you filled the tank, it would act normally until the fuel level reached the pin hole, then you would tend to have erratic fuel delivery.

Putting a full cartridge filter in line between the pickup and the pump will further amplify the issue since the fuel line looses the continuity to the suction to the fuel when the level reveals the hole.

Put a screen filter before the pump(s), then a cartridge filter before the carb(s).

Drain the tank occasionally and slosh the tank with tank cleaner and use the liquid Teflon coating.

You can't slosh the tank with the engine in the car though but when you do a rebuild best do it.

When you store the car, make sure you store it with a full tank of fresh gas in it also to reduce the oxidation to the interior exposed surfaces of the tank. That helps.

If you have the early tank with the intergal fuel pickup, put a new pickup in. The replacement pickup will be on the float assembly and is also larger in diameter then the original.

With the early tank and pickup design you have the potential of the fuel pick up finally rusting through somewhere out on the road.

If you do, you are just plain stuck out there. If you were quick enough to think on your feet and realize what just happened you might be smart enough to figure out how to rig up a Cheech & Chong type emergency pick up, but it won't be easy to do.

http://www.youtube.com/watch?v=7w4t8FhYPE8

You don't want that happening to you.

Leave the original integral alone and just plug it externally. It makes a great return line if you go to fuel injection in the future and won't hurt anything left in place.

Thanks Doug..some good info there. I can easily blow back on the line and hear bubbles in the tank so I don't believe the sock is blocked ( or possibly not on) It may be due to too little fuel in the tank as I had totally drained it to removed the bottom plug and have a look inside for inspection purposes. The car has not run since 1986 so I'm going through everything. I'm going to fill the cartridge cannister with fuel and try to get a prime to that point after I bring the tank to 3/4 full. Thanks for the info...

George:

Thanks for the info...it makes sense to me. I can blow through the line easily hearing bubbles in the tank. I believe more fuel in the tank and priming the cannister will help greatly. Appreciate the input.

quote:

Originally posted by George Pence:
If you're using the OEM fuel pump suction line (which is too small in diameter by the way) it has a little nylon sock on the end that is known for becoming completely plugged. The usual remedy is to blow air backwards through the line, which blows the brittle nylon sock completely off the end of the tube and thereby resolves the problem; but it makes a fuel pump suction filter mandatory to replace the pump inlet filtering originally provided by the nylon sock. Fuel pump suction filters are usually recommended by all high performance pump manufacturers, with filtration in the 100 micron range.

If the level of fuel in the tank is very low, and the fuel pump inlet line is empty, it may be too much lift for the pump, or the pump is operating vapor locked. Raising the level of the fuel in the tank, or pre-filling the suction line may resolve the problem. Slightly pressurizing the fuel tank (blowing in the tank vent) may be another way to get the fuel flowing.

-G

I always pour a little fuel down the carb and start the engine. The 5 odd seconds that it runs is usually enough to prime the system. A running engine will pump more fuel up in that 5 seconds than 30 seconds of cranking ever will. I know it sounds dodgy but I have done it heaps and works every time.

[QUOTE]Originally posted by johnek74Pantera:
George:

Thanks for the info...it makes sense to me. I can blow through the line easily hearing bubbles in the tank. I believe more fuel in the tank and priming the canister will help greatly. Appreciate the input. [QUOTE]

This all depends on where the air bubbles are coming from. If the pickup tube has holed through, you will get air bubbles through that.

How does hearing air bubbles help in determining
the source of the problem?

As far as pouring gas down a dry carb and priming the engine with that, that is not the way to go.

Why not just flick off those sweat droplets from the sticks of dynamite?

A dry Holley is a very dangerous carb to force prime.

First of all, the bowl gaskets dry out and shrink after being exposed to fuel, then let sit to dry out.

Second, the needle and seat will also dry out and take a little time to soften up again after being exposed to new fuel.

That means the carb is very highly likely to flood like Niagara Falls.

Why not just play Russian Roulette with an automatic hand gun?

When I blew through the fuel line and heard bubbles, I only had roughly 3 gallons of fuel in the tank so I am fairly confident that the bubbles came at the end of the pickup...good enough for me. The holley is a non issue as I'm running quad webber 48 IDA's. I agree with George and believe some more fuel in the tank and a little persuasion and we'll be on our way. It ain't rocket science so I will not attempt to make it sound any more difficult than it is..)

hearing air bubbles allows me to determine that: A: the pickup is not blocked inside the tank and B: there is no obstruction between the pump intake and the tank.

quote:

Originally posted by PanteraDoug:
[QUOTE]Originally posted by johnek74Pantera:
George:

Thanks for the info...it makes sense to me. I can blow through the line easily hearing bubbles in the tank. I believe more fuel in the tank and priming the canister will help greatly. Appreciate the input. [QUOTE]

This all depends on where the air bubbles are coming from. If the pickup tube has holed through, you will get air bubbles through that.

How does hearing air bubbles help in determining
the source of the problem?

As far as pouring gas down a dry carb and priming the engine with that, that is not the way to go.

Why not just flick off those sweat droplets from the sticks of dynamite?

A dry Holley is a very dangerous carb to force prime.

First of all, the bowl gaskets dry out and shrink after being exposed to fuel, then let sit to dry out.

Second, the needle and seat will also dry out and take a little time to soften up again after being exposed to new fuel.

That means the carb is very highly likely to flood like Niagara Falls.

Why not just play Russian Roulette with an automatic hand gun?

Sometimes you just have to pull that trigger and see what happens. If we spent our life worrying about what might happen we wouldn't get up in the morning!

quote:

Originally posted by PanteraWanabe:

quote:

Originally posted by PanteraDoug:
[QUOTE]Originally posted by johnek74Pantera:
George:

Thanks for the info...it makes sense to me. I can blow through the line easily hearing bubbles in the tank. I believe more fuel in the tank and priming the canister will help greatly. Appreciate the input. [QUOTE]

This all depends on where the air bubbles are coming from. If the pickup tube has holed through, you will get air bubbles through that.

How does hearing air bubbles help in determining
the source of the problem?

As far as pouring gas down a dry carb and priming the engine with that, that is not the way to go.

Why not just flick off those sweat droplets from the sticks of dynamite?

A dry Holley is a very dangerous carb to force prime.

First of all, the bowl gaskets dry out and shrink after being exposed to fuel, then let sit to dry out.

Second, the needle and seat will also dry out and take a little time to soften up again after being exposed to new fuel.

That means the carb is very highly likely to flood like Niagara Falls.

Why not just play Russian Roulette with an automatic hand gun?

Sometimes you just have to pull that trigger and see what happens. If we spent our life worrying about what might happen we wouldn't get up in the morning!

I play Russian Roulette all the time.

I know it's coming though and keep ducking?

I have seen many times a piece of trash gets caught in the check valve of the pump. The diaphragm moves but no fuel. If its sucking air back in through the outlet when its on the intake stroke you have a problem. Saw this on a brand new edelbrock pump right out of the box.

Doug is correct in being a safety baby. Anytime I mess with raw gas I have a couple of fire bottles close by. (Last fire - yep, we have spark - was accompanied by a fire bottle showing full charge and being worthless!)

I just went through this with a big block Torino that has been sitting for 5 years. Ended up priming the dry carb through the fuel bowl vents and letting the spillage evaporate. Worked ok, but I understand a cracked accel pump diaphram will leak to the outside of the carb.

Be careful out there!

"Yes, we have spark"