Depth reach of sierra submersible pump

[keith_h]

Is anyone in a position to be able to measure the distance on a Sierra submersible pump from the tank flange to the pickup point below it.

[philcoyle]

Re: Depth reach of sierra submersible pump

The base or pick up part of the pump should be located in a fixture which should be already welded to the bottom of the tank.
Measure the length of your pump from the flange to the pump base, compare the distance from tank bottom to pump aperture, should be an equal measurement, or there should be a means of moving the pick up pipe to compensate either up or down.

[keith_h]

Re: Depth reach of sierra submersible pump

Hi Phil,
If you look at the photo in the first reply in my Cardinal Sin thread what I am after is the distance from the flange at the extreme right of the photo to the pick-up point where the filters fit just below the pump (just off the left hand side of the photo). I was getting no fuel at the engine so I went back to the pump. I took off the fuel lines and fitted a piece of plastic tube between the output and the input pipes on the flange and when I turn on the ignition although I hear the pump run for its short 1 - 2 second burst I see no fuel movement - as though either the new pump is faulty or the pickup point is above the level of petrol. Before I fired it up the first time after fitting the new pump I had put just over 3 gallons in the tank. When I got no response to ignition I added another nearly 2 gallons. I find it hard to believe the pick-up is above the level of petrol now but I just wanted to double check before I start all over removing the tank etc (stranger things have happened at sea !!)

[Mike]

Re: Depth reach of sierra submersible pump

Hi Phil,
If you look at the photo in the first reply in my Cardinal Sin thread what I am after is the distance from the flange at the extreme right of the photo to the pick-up point where the filters fit just below the pump (just off the left hand side of the photo). I was getting no fuel at the engine so I went back to the pump. I took off the fuel lines and fitted a piece of plastic tube between the output and the input pipes on the flange and when I turn on the ignition although I hear the pump run for its short 1 - 2 second burst I see no fuel movement - as though either the new pump is faulty or the pickup point is above the level of petrol. Before I fired it up the first time after fitting the new pump I had put just over 3 gallons in the tank. When I got no response to ignition I added another nearly 2 gallons. I find it hard to believe the pick-up is above the level of petrol now but I just wanted to double check before I start all over removing the tank etc (stranger things have happened at sea !!)

May be a stupid question but does the pumps wiring affect which way it rotates?

[keith_h]

Re: Depth reach of sierra submersible pump

Not a stupid question and one that I had considered. I think I remember the spade terminals being different widths so that you can't get them wrong. Can anyone confirm that?

[philcoyle]

Re: Depth reach of sierra submersible pump

Just a thought, the wires may be the correct way around at the pump end, but what about back along the loom. Also as you said the fuel system was drained completely and if your pump is running (ignition only) the air trapped in the fuel line has nowhere to go. the 2 second burst from the ECU wont be enough to completely push out all the air , you will have to bleed the air out of the system as the pump will only push fuel not air. You have to remember that EFi is a closed pressurised system unlike carb set up, running the pump will only force the fuel until it meets the air in your fuel system and then the air has nowhere to go until the air is released. The air will just keep on compressing and then expanding when the pump stops, its like playing with a bicycle pump by putting your finger over the end and trying to pump it. One final thought was the pump motor an identical replacement?

[Mike]

Re: Depth reach of sierra submersible pump

Just a thought, the wires may be the correct way around at the pump end, but what about back along the loom. Also as you said the fuel system was drained completely and if your pump is running (ignition only) the air trapped in the fuel line has nowhere to go. the 2 second burst from the ECU wont be enough to completely push out all the air , you will have to bleed the air out of the system as the pump will only push fuel not air. You have to remember that EFi is a closed pressurised system unlike carb set up, running the pump will only force the fuel until it meets the air in your fuel system and then the air has nowhere to go until the air is released. The air will just keep on compressing and then expanding when the pump stops, its like playing with a bicycle pump by putting your finger over the end and trying to pump it. One final thought was the pump motor an identical replacement?

Phil
Would turning the engine over and over on the starter ignition not bleed the fuel pump?

It certainly would on my BMW set up, as the fuel pump is powered up by a crank, (or cam?) sensor which detects engine movement and provides an earth to the fuel pump relay.

[philcoyle]

Re: Depth reach of sierra submersible pump

Hi Mike ,
There's no reason why it would not. I just think its unnecessary to run the starter motor, but if there is no problem with running the battery flat, or overheating the startermotor, then whatever floats your boat! Or you could disconnect the pump from the wiring loom and connect it direct to the battery a couple of crocodile clips and a long piece of wire, disconnect fuel pipe from the engine, stick pipe into container and away you go.
The idea is to get the fuel at the furthest point away from the tank how you do it is a matter of choice, if it works for you by taking all your clothes off and running through a nettle patch, great!, as long as it works does it really matter. LOL and funny faces!

[keith_h]

Re: Depth reach of sierra submersible pump

I've gone back to the tank and pump. I took the pipes off of the pump and fitted a short length of 6mm i.d. plastic hose to each of the pump output and the return. I blew down them in turn. I could hear bubbles in the tank with one of them and couldn't blow at all into the other. I then decided that the pump should be able to prime itself if it had just a short piece of tube (about 10") looped from one pipe to the other. I saw no fuel in the plastic pipe when it did its 1 - 2 second burst. The new pump was sold to me as a direct replacement so I am comin to the awful thought that all this effort was because of a faulty new pump !!

[philcoyle]

Re: Depth reach of sierra submersible pump

Hi Keith, Have you tried to run the pump on the bench just to see if it does run and if it pumps.

[keith_h]

Re: Depth reach of sierra submersible pump

Hi Phil,

I have been desperately trying to avoid taking the tank out again so a bench test of the pump will come when every other avenue has failed. My latest thought is to take the electrical supply away from the pump and fix a separate 12v supply to it so that I can run it for a few seconds to see if I can force some fuel through. I imagine these pumps are not spec'd for permanent running so I shall have to be careful not to burn the new pup out

[philcoyle]

Re: Depth reach of sierra submersible pump

Hi Keith,
Once the engine starts, the pump runs continuously. The flow of fuel (45p.s.i.) approx. is controlled by the fuel pressure regulator. The fuel system remains constant thanks to the regulator, the pump does not vary in speed when running, it will charge the system up to 5 bar, ignition on, when the engine runs the injectors opening will cause a drop in pressure and the regulator controls any excessive pressure.
The pump cools itself by being submerged in fuel, so as long as you run the pump in fuel no problems, just be extremely cautious when connecting a live feed to the pump, sparks and fuel not a good combo.
Fit wires to the pump securely and make sure the battery feed is in the next county when you connect it, or a few yards away at least.
Incidentally there are few or if any at all records of a fire being caused by an intank fuel pump.
Unless you can vent the air in the fuel line to atmosphere at the engine end (loosen/disconnect pipe or clip) you are not going to be able to fill the fuel system, air compresses under pressure and the fuel will not.
If the air has nowhere to go you may still be there this time next year.
The regulator is designed to open when fuel pressure is over 45psi (manufacturers vary) it will not open by air pressure alone.
A thought crossed my mind that when you bought your new pump motor, did you state that it must be capable of 3- 5 bar running 45-75psi , for the pedantic; I bar is 14.7 psi and it wont make your car run any better if you can be bothered to do the maths. Smiley face, merry Christmas,and children should not play with matches with high pressure fuel nearby.
Phil.

The pump does not have a BRAIN or a SENSOR that will tell it if the fuel pressure is high or low, likewise it does not know if the engine is running at tick over or flat out, or if you are driving Miss Daisy or you are driving like your R's is on fire, IT IS JUST A PUMP it pumps fuel it can't pump air it is a FUEL pump.

One last thing , please don't get involved if you are fortunate to have a self bleeding system, this one isn't, and will only lead to confusion, no offence meant but we are dealing with a very early EFi system.

And if you really want to know, pumps usually move liquids, and compressors move gasses, therefore a pump will not move air ( gas )in a fuel system only the liquid, if you can, fill the filter up manually and get as much fuel into the system as is humanly possible. Its only when you have a sufficient volume of fuel to replace the air it will push the air out if it is vented to the outside world.