New Fuel Pump - Need to pime?

Installing new fuel pump in a '94 4.3 Merc. Sorry for my stupidity, but does the new pump need to be primed with fuel? One part of me says no, it must be able to draw when the fuel drains down below the pump from gravity from sitting. The other part of me thinks the pump possibly wouldnt be able to create the necessary vacuum to draw the gas form the tank through the filter before reaching the pump if I don't. Installation guide doesnt mention it, but then again, it really doesnt mention much of anything other than how to adapt the new wiring for the pump.

Thanks for putting up with my stupidity....and any input.

Steve O!

Re: New Fuel Pump - Need to pime?

what i do is pour a couple of ounces down the carb to get the engine to start. you may have to do this a couple of times or just sit there with a dixie cup full of gas and sloooowly pour it down while the engine is running.
That will get the fuel system full.
ps~ be carefull.... i don't warranty eyebrows

Re: New Fuel Pump - Need to pime?

Well, with newer engines, everytime you turn on the ignition switch the fuel pump will run for a few seconds. If that is not the case with your's, you could do as the above poster suggested and manualy feed fuel to the engine until it is primed. The other thought is to manually feed power to the pump before you connect it to the wiring harness.

Re: New Fuel Pump - Need to pime?

but does the new pump need to be primed with fuel?

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Nope,.... Supply the Power,+ it'll Pump....

Re: New Fuel Pump - Need to pime?

waterone1@aol.com said:

Well, with newer engines, everytime you turn on the ignition switch the fuel pump will run for a few seconds.

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It only works that way with fuel injection.

The pump gets power only while starting or after oil pressure builds and closes the switch.

First time may require a little extra cranking, but the pump will create enough suction to draw fuel from the tank.

Re: New Fuel Pump - Need to pime?

If you have a cannister type water separating fuel filter and it is easy to remove and put back on while it is full of fuel then you can remove the fuel filter and fill it with fuel and reinstall, that will help the prime. This method has a great potential for spillage so take this into consideration.

Re: New Fuel Pump - Need to pime?

good tip about filling the filter, but unless he replaced it, it should not be empty.

Re: New Fuel Pump - Need to pime?

If its anything like the gm tbi systems(which i believe it is) just cycle the key a few times every 30 seconds. You should hear it run for 3 seconds each time.

Re: New Fuel Pump - Need to pime?

abj87 said:

If its anything like the gm tbi systems(which i believe it is) just cycle the key a few times every 30 seconds. You should hear it run for 3 seconds each time.

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Ayuh,....

As noted by Sheba,.... It Don't work that way......

Probably because it Isn't a GM tbi system.... It's a Carbed motor....

Re: New Fuel Pump - Need to pime?

Wires are mentioned in the first post, so i assumed never mind me, carry on.:redface:

Re: New Fuel Pump - Need to pime?

merc does use an electric pump feeding some carbs

Re: New Fuel Pump - Need to pime?

Thanks guys! It is a carbed 4.3 with an electric fuel pump. With the advice, I will try the hit the key on several occasions to have the pump kick in for a few seconds at a time to try and get the fuel to the carb.

Thanks again, hated to run a $237.99 fuel pump dry and take the chance of frying it.

Steve O!

Re: New Fuel Pump - Need to pime?

I will try the hit the key on several occasions to have the pump kick in for a few seconds at a time to try and get the fuel to the carb.

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Ayuh,....

I Guess you didn't bother to read Sheba,+ My responces,....

It Don't Work That Way....

The motor has to be cranking with the starter for the fuel pump to get Power.....

Re: New Fuel Pump - Need to pime?

or........ you could just pour gas down the carb.....

Re: New Fuel Pump - Need to pime?

Getting fuel into the carb bowl is best, it will run a lot longer that way and give the fuel pump a long run to finish priming and fill all the lines and filters up to the carb. On Auto carbs it was not too difficult as you could direct a small container of fuel into a small funnel or tube aimed at the fuel bowl vent. On some Marine carbs it is more difficult as the vent tubes are not as easy to aim at.

This is just an idea, and may not be worth the trouble, but I know on my boat's carb if I ever needed it to run a while without depending on the fuel pump I would take a flexible hose and slide it up the bottom of the vent tube and hold it up and hook up a small enough funnel to the other end or aim a small funnel at that tube and fill the bowl slowly that way. Some fuel gets into the throat as well and it should start right up and have enough fuel in the bowl to act normal for a while.

On some of my auto carbs that had flexible lines into the carb I would disconnect that line from the filter or pump and use that line to fill the carb. That got me home one time without a tow when the fuel pump went out.