Thread On Relocating Fuel Pump? Options

[kenshapiro2002]

I swear...I searched. Can't get down to less than 53 pages,and none of the first few pages have any pictures. I do remember seeing some thread here...I think...help?

[PeeGreen 914]

I'm not at home or I would. Just post some pictures and a little how to. What are you having trouble with and where are you relocating to?

[SirAndy]

Relocating Fuel Pump

Why? (IMG:style_emoticons/default/confused24.gif)

[jmill]

Relocating Fuel Pump

Why? (IMG:style_emoticons/default/confused24.gif)

This may answer your question:

NPSH = the net (left over) positive pressure of suction force into a pump intake after friction loss has occurred. Liquid head height or liquid head pressure + gravity pressure, minus friction loss, leaves a net head pressure of force into the pump.

The longer the fuel line, before the pump, the more friction loss you have resulting in less net positive suction head.

FourBlades thread: http://www.914world.com/bbs2/index.php?sho...&hl=cb+pump

[SirAndy]

This may answer your question:

NPSH = the net (left over) positive pressure of suction force into a pump intake after friction loss has occurred. Liquid head height or liquid head pressure + gravity pressure, minus friction loss, leaves a net head pressure of force into the pump.

The longer the fuel line, before the pump, the more friction loss you have resulting in less net positive suction head.

FourBlades thread: http://www.914world.com/bbs2/index.php?sho...&hl=cb+pump

So, in the real world, no 914 with the fuel pump in the rear will ever run again? (IMG:style_emoticons/default/confused24.gif)

My 2056 with CB rotary pump in the rear had plenty of problems.
Delivering fuel was not one of them and neither was "vapor lock" ...
(IMG:style_emoticons/default/stirthepot.gif) Andy

[jmill]

I didn't say it wouldn't work. I said it would have less NPSH. Which basically leads to a less efficient pump.

[SirAndy]

I didn't say it wouldn't work. I said it would have less NPSH. Which basically leads to a less efficient pump.

Which is how big of a problem? (IMG:style_emoticons/default/idea.gif)

[kenshapiro2002]

Gonna pull the tank to replace the sock...figured I'd relocate the pump up there as an improvement? Less heat, and all that jibberish about it being more efficient up there! (IMG:style_emoticons/default/biggrin.gif)

[SLITS]

I never had "vapor lock" either on my '74 until I pulled the grade out of Lauglin, NV in about 120 degree heat. After it cooled, it would run for about 20 miles before VL again. Took me 11 hours to make a 4 hour trip.

2nd case involves a car in the desert heat of Las Vegas. Normal running, VL. Car would quit, ccol down, run again. Moved fuel pump to front, mounted just above rack ... never a problem again.

If I were to do it again, I would cut the stock hole like on the '75 - '76, obrtain the bracket, mount and cover for same, and install ... stock location. Under the rack the fuel filter was being rubbed by the rack bellows. Went to an aftermarket smaller diameter filter to alleviate this.

Main problem is loss of fuel pressure in the rail on shutdown. It bleeds off rapidly with a VL fuel pump. Could also be the check valve in the pump going south.

Anyway, SS lines were used for the thru tunnel pressure line. Stock return line left in place.

That's just my opinion.

Oh, and the jibberish about electric roller pumps being better pushers than suckers is very true. Electric roller pumps operate in a flooded suction conditon; they will not pull the fluid to much of a height above the fuel level in the tank (hence booster "in-tank" pumps to feed the roller pump in some cars).

A mechanical or electic diaphram pump is a sucker as it will prime itself above the fuel level (draws a vacuum on the supply line).

[jmill]

Which is how big of a problem? (IMG:style_emoticons/default/idea.gif)

If you looking to maximize the efficiency of your fuel system it's a step backwards. I doubt Ken would run into issues leaving it in the stock location, especially if he went with SS lines. If your on the ragged edge of your fuel system it certainly would help to relocate. It will result in more volume and pressure.

[orange914]

this link isn't necessarily on relocating the pump, but it does show you helpful info. on it's front under tank mounting.

i relocated our 73 to the front mainly because we where doing the center hard lines anyway. AND i live in 100* + weather where vapor lock is an issue. can't hurt, i figure high dollar engineers usually have better reasons than me. (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/beerchug.gif)

[davesprinkle]

Wherever your pump is located, you need to replace your fuel lines.

Don't even think about pressurizing the stock plastic lines, unless you want to burn your 914 to the ground.

By the way, whey you order your lines, be sure to tell Chris Foley that you are relocating the pump, so that he can assist with line sizing. Otherwise, you'll have one hell of a diameter-adapter headache.

[PeeGreen 914]

I chose to put mine in the front trunk as I wanted to have easy access to it if it decided to crap out on me at the track. Ironically, the secnd event I went to I had to replace the pump and it only took 5 minutes because of what I did.

However, it does make the front trunk less usable. I didn't care about that as my car is just for AX but you could do the same as I did and make it more usable.

For the wiring I just ran wire from the possitive wire off the old pump up to the front with a cut off switch in between (safety and theft prevention). Then I ground it off the healight grounds.

eh... still can't find the pictures from when I did it. I know they are here somewhere.

[kenshapiro2002]

What link? I don't see any link. (IMG:style_emoticons/default/WTF.gif)

this link isn't necessarily on relocating the pump, but it does show you helpful info. on it's front under tank mounting.

i relocated our 73 to the front mainly because we where doing the center hard lines anyway. AND i live in 100* + weather where vapor lock is an issue. can't hurt, i figure high dollar engineers usually have better reasons than me. (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/beerchug.gif)

[kenshapiro2002]

I'm guessing if you have "easy access" you didn't put it under the tank? Mine is a '70 with no access panel, unless I create one. I'd rather have mine outside of the "pit" unless ya'll convince me otherwise.

Where'd you route the (+) wire? Where'd you put your switch?

I chose to put mine in the front trunk as I wanted to have easy access to it if it decided to crap out on me at the track. Ironically, the secnd event I went to I had to replace the pump and it only took 5 minutes because of what I did.

However, it does make the front trunk less usable. I didn't care about that as my car is just for AX but you could do the same as I did and make it more usable.

For the wiring I just ran wire from the possitive wire off the old pump up to the front with a cut off switch in between (safety and theft prevention). Then I ground it off the healight grounds.

eh... still can't find the pictures from when I did it. I know they are here somewhere.

[VaccaRabite]

In the 75-76 cars there is a bumped out access panel that the fuel pump attaches to under the gas tank. it makes doing work a snap. Take out 4 screws, and when you pull out the panel that pump pulls out too.

I am using a CB rotary pump, if you are going to stick with carbs, that is what you should get and use as well. You will need to run a + wire to the pump, but that is not a problem.

Just make sure to leave yourself a good service loop of fuel line under the tank so that as you fiddle with the pump you are not stressing the fuel hose. Also makes it 8much* easier pt pull the tank.

In the lower left hand of this pick you can see the black bump out where the later fuel pumps were located. The pic is looking down at my front trunk while fixing 30 years of PO horribleness.
(IMG:http://farm1.static.flickr.com/41/108161146_a2f0d2b1fe.jpg)
Zach

[kenshapiro2002]

The later fuel pumps were in the trunk...not under the fuel tank?

In the 75-76 cars there is a bumped out access panel that the fuel pump attaches to under the gas tank. it makes doing work a snap. Take out 4 screws, and when you pull out the panel that pump pulls out too.

I am using a CB rotary pump, if you are going to stick with carbs, that is what you should get and use as well. You will need to run a + wire to the pump, but that is not a problem.

Just make sure to leave yourself a good service loop of fuel line under the tank so that as you fiddle with the pump you are not stressing the fuel hose. Also makes it 8much* easier pt pull the tank.

In the lower left hand of this pick you can see the black bump out where the later fuel pumps were located. The pic is looking down at my front trunk while fixing 30 years of PO horribleness.
[img][/img]
Zach

[type47]

The later fuel pumps were in the trunk...not under the fuel tank?

That is correct. There is an access hole in the vertical panel (as shown by Zach) and the fuel pump was/is mounted to the cover to the hole and the pump then is in the gas tank compartment, not under the skid plate covering the steering rack.

[kenshapiro2002]

Just to clarify...I was notcorrect. The pump is under the fuel tank...not in the trunk. It is just accessible through the trunk, right?

The later fuel pumps were in the trunk...not under the fuel tank?

That is correct. There is an access hole in the vertical panel (as shown by Zach) and the fuel pump was/is mounted to the cover to the hole and the pump then is in the gas tank compartment, not under the skid plate covering the steering rack.

[type47]

??? late fuel pumps are physically in the same space as the gas tank and are accessible through the front trunk where a small panel is located on the vertical wall covering the access hole.