Newbie's First Nightmare!!, Fuel Pump Fun Options

[aveale]

Well, I am sure this is a rite of passage.

I have been having some serious fuel issues for my 73 2.0.

My original fuel pump (fp) did not leak until i decided to change some of the hoses....

Ordered used replacement from a nice chap in Toronto at Porschapart but it leaked too.

Ordered a new one for a 1975 (?) and up and slid her into place. As all of YOU know, the old pump as 2 Return outlets (D and R) and the new one has one, so I "T'd" everthing together so that it receives fuel from the out port on my new pump.

It does not want to start...occasionally I get some sputters...whereas before it would start at the first crank!!

So, my questions are.....

1- was having everything joined (T'd) together the correct thing to do?

the present set up is - Tank->Filter->FP->two splitters that go to both fuel rails and the fuel return line(?)

2- do i have to prime the blasted thing or any of the lines?
3- how many cranks to get fuel to the injectors? - is it more than 100?
4- has anybody had success with the fuel pump upgrade that they can share?
5- why did I get myself into this?
6- will my wife ever forgive me for spending 40+ hours in the garage sniffing and smelling like gas?

Ahhh life is funny.

Thank you everyone!

T

[bob174]

Not sure about "t"-ing the return into your pump. I assume that your pump's two connections are for suction, from the tank, and pressure, to the fuel rails. Look at the FI diagram on Pelican's board for the original arrangement...

http://www.pelicanparts.com/914/technical_...4_20FI_diag.htm

I still don't understand what the "R" (return?) port on the original pump is for--it's maybe some kind of internal bypass? Anyway, it seems, by looking at that image, that on your '75 pump you've probably t-ed together your pressurized port and the return. If this is the case you will have defeated the pressure regulation in the system. I'd suggest running the return line directly to the return spigot at the tank, and don't tee it into anything. Don't know if this will work correctly with the '75 pump, but I'm sure someone else will chime in if I'm screwed up.

When you're done, you'll need to purge the air from the system. From Jim Thorusen's article on Pelican Parts site:

"Put some fuel in the tank, and short pins 30 and 87 of the fuel pump relay
socket with a suitable jumper (relay removed).

The pump should run, and fuel should be observed to circulate in
the plastic lines in the engine bay. (At least at first, when some
bubbles and dirt should be in evidence.) Allow the pump to run for 2
or 3 minutes, to purge all dirt from the lines. While it is running,
inspect the pump itself and all other fuel line connections for leaks."

This is in a tech article on relocating the fuel pump from the engine compartment to the front trunk, but the procedure is applicable because you probably drained the lines (intentionally or not) when you pulled the pump out. You can identify which relay is the fuel pump relay by looking at the schematic in the Haynes manual, or someone here may have a picture and be kind enough to post it for you. When you do this, if you're by the tank, you'll hear the air being forced back into the tank from the return line. I just let it run until I couldn't hear any more air, and then cranked her up.

Why you got yourself into this? Well, the cars kick ass, of course. And you're a mechanically inclined weenie like the rest of us, that has nothing else on which to spend time or money.

You gotta work the wife one on your own. I got my own problems in that area. Mine happens to be very forgiving, and is used to my--"it should only take a couple hours..." line.

[Rhodes71/914]

I have a '71 that has a later syle pump in it mine is routed like this - tank>filter>fuel pump>fuel rail for cyl 3&4 (pass. side)>cold start injector>fuel rail for cyl 1&2 (drivers side)>pressure regulator>return line to tank.

It's not cranking of the engine that gets fuel to the injectors. when you first turn the key on the fuel pump runs for about 5 sec. it also runs as you crank to start. Whenever I am messing with fuel lines/injectors i turn the key on and off a few time to build the pressure up, the injectors need something like 29psi to work correctly. It also helps to have a pressure gauge, you can connect one to the fuel rail that is on the drivers side for testing purposes.

[McMark]

(IMG:style_emoticons/default/agree.gif) No Ts are necessary. You're over pressurizing the fuel and getting an extremely rich mixture.

[aveale]

I'd suggest running the return line directly to the return spigot at the tank, and don't tee it into anything. Don't know if this will work correctly with the '75 pump, but I'm sure someone else will chime in if I'm screwed up.

Great replies on my problems and good to hear that other people are using the "it should only take a couple of hours" line with their loved ones!!

Just a little confused about this return line. If I understand correctly, I must "close the loop" - with the return line - not behind the pump (pressurized side - where I have it now-) but infront of it (unpressurized side - between the tank and the pump).

Does this sound right?

Thanx so much for the responses, and one day I hope to pass some learned knowledge to the next newbie!

T

[jim912928]

I'ts real simple...ther "R" return line needs to be fed back into the gas tank...your gas tank should have 2 connectors on the bottom..an outlet (where there will be a little screen on the inside) and an inlet (return fuel). To use a 75/76 fuel pump the sequence is:

outlet from tank to fuel pump...fuel pump then goes to a filter...filter then goes to fuel line that feeds the engine...gas goes around the FI system and dumps a return line that NOW should go straight to back to your gas tank.

[aveale]

Now we are cooking!!

The lights just came on.

Cheers,

T

[aveale]

Well I dashed home at lunch - did what was asked and I flew the car back to work!!

What a great feeling!

I could not have done it without y'all!!

Cheers, and sleep well.

T

[Rhodes71/914]

Gald you got it all worked out. (IMG:style_emoticons/default/smilie_pokal.gif)

[type47]

what just struck me about jim912928's post is that he locates the filter after the pump. now, i don't remember how mine is hooked up but i was thinking as i read this that i would want the filter before the pump so the pump gets clean liquid thru it.... actual factory order may be as he states... not a sermon, just a thought....

[jim912928]

lol..I'm going from memory (and I'm over 40 so I shouldn't do that!)...but I do believe you are right on the fuel filter being in front of the pump (I have a 75 with all the stuff in the front under the tank) the order is:

1. outlet from Fuel tank
2. small hose to filter
3. big hose out of filter into fuel pump inlet
4. little hose out of fuel pump to fuel line in tunnel
5. fuel line out of tunnel to fuel rail and all the FI crapola
6. return line to fuel line in tunnel
7. small hose to inlet on fuel tank

Thanks for jogging the ole brain cells!

Jim

[aveale]

I was thinking about the position of the filter too.

It only makes sense that we try to keep the flow of the gas as smooth as possible and a filter would definately disrupt the flow pattern!

Thanx again everyone.

T