Hello .
New here and did search but not finding what I "think" I am asking.

73 1.7 with D jet .... running very rich .
Starts well cold .... flooded warm and again very rich.

I checked the fuel pressure by t-ing off the line just after the drivers side injectors.
I had a reading of 70 lbs .
The pressure regulator seemed suspect to me and was "a bit rough" .
Purchased a new one and still at 70 lbs ???

Help much appreciated . I have read the many write ups by using google but seem to be a bit lost .

thanks for any help / direction

Fuel pressure must be at 30 ponds max . The regulator is adjustable .

Check your return line for a restriction/crimp somewhere.

Is your return line plugged?

1. Make sure the gauge is calibrated.

2. Like James has said...make sure the return line is not plugged. Jeff Bowlsby has a great diagram on his web site and has posted it here before.

3. Fuel pressure for stock D-jet is 30-32 lbs.

4. Once the fuel pressure is sorted, check the MPS by vacuum check. Harbor Frieght has a "good enough" gauge if you don't have a good gauge with an indicator. Needs to hold at least 15 lbs. vacuum for at least 5 mins. There is a spec for it, I've forgot exactly, but it is somewhere around there.

Report back once you've done these things.

Whoops....one other thing after you check the MPS diaphram.

Make sure your injectors are not stuck open.

You can have them cleaned and flow checked by someone like Witchunter for about 50 bucks or so.

Thanks guys ...
Yes I do have a book, and know to try to hit 30 lbs.
I will check the return line.

I checked every fuel line in the engine bay today .. removed clamps section by section and all were clear.

Am I correct the return is from Fuel pump back to tank ?
If so ... to be %100 sure of being clear is it a removal of tank or can i shoot air through the line ?

Added Jeff's site to my "914 bookmarks"

spent some more time ...

Ok ... p-lease don't laugh .
I only have 1 plastic line coming from underside to engine bay ???
My hoses make 1 big loop , right there . I do not see a return line back



Where the return should be ( there is a "Y" back to the supply ! )

We like photos...show us what you have.

this is what my schematic looks like

the single feed line

& the "Y"

That explains the high pressure. You need a return line to the tank.

Keith

Thanks ... this is odd . just purchased the car from a well known 914 guy . ... car sat for a while .
I am wondering if someone monkeyed with it . & thats why it sat .
I am running on 70 lbs pressure .

I will jack up and see what silly things are at the fuel pump .

Hopefully just correctly re- route the lines .

Thanks (i'll keep you posted ... I just knew I wasn't THAT crazy

Don't ... Unless you like car-becue ...

No Car B Que for me .
I'll check more , but the return line at fuel pump is new & different clamps.

So does that "Y" belong down there on that line with the return from the Pressure Regulator ?

Found this photo here on this forum . the "Y" does indeed belong on the return line at the fuel pump !

Well, if you have a more modern replacement fuel pump, you would not have a need for the y fitting, but you will still need a return line to the tank.

Sorry to say, but you need to buy a line from Tangering, buy both, and replace them to the tank.

the following is how I installed the stainless steel lines (green) from tangerine...

when I posted this over a year ago, and asked for a critique, no one responded..

I still do not understand the "Y" and how that works. ????

blue is return line..

Click to view attachment

tks

randal

I'd say you've been nothing short of lucky to this point; Andy is 100% correct. Please don't drive the car until you redo the fuel lines completely and get rid of that nylon line... I'm sure that thing is as brittle as hell, mine looked rather like that and snapped when I bent it.

Best thing you can do for your car at this point.

That's a correct install, nothing else to comment on.

Your fuel is supposed to go from the tank, to all of the injectors, and back to the tank again. The injectors use what they need, of course, but a whole lot more fuel is pumped than they could ever possibly use. So you need a line that goes from the fuel pressure regulator back to the tank.

The fuel pump is supposed to be able to dump excess pressure that it sees (a higher pressure than the FPR regulates to) in order to keep from blowing out seals or some such. It needs to be able to dump that excess back into the fuel tank as well.

The Y ties together the bleed-off line from the fuel pump (labeled "R") and the return from the FPR, and sends them back to the fuel tank.

Later, they figured out that they didn't really need the return from the pump if they changed the design a bit, so in the 75-76 914s the Y was eliminated. (And also if you convert over to a more modern pump.)

--DD

From what I recall when shopping for a pump last time the stock inline pumps are rated at 65-70 psi.

The Y is used to route the overflow fuel from both the pressure regulator and the fuel pump back into the tank.

THANKS !
I re-routed the new lines ( almost everywhere) and installed the "Y" as in the above pics (at the fuel pump) ....
29 lbs !
Wow ... Smooth . Idles . Got power .
Super happy . Thanks to all for information.
I hope to be able to return the favor here.
Now ... Very motivated to work on smaller stuff .

never mind the below, as i missed the following "The Y is used to route the overflow fuel from both the pressure regulator and the fuel pump back into the tank."

thank you, i kind of understand now. something inside the pump allows for
fuel to be routed out into the return line under pressure so the return from the
fuel injector loop combined with the fuel pump pressures the fuel to move to
where there is no pressure, and back to the fuel tank the fuel goes.
tks


what i did not understand was how the Y worked in that

the fuel is under pressure returning from the fuel injector loop and then it

comes to a Y .... is the short piece also under pressure from the fuel pump ?

seems like they would be at odds with each other.. as where does the fuel

pump obtain a continued source of fuel to send down stream to the fuel tank?

obviously i do not understand how this works.

tks

randal

That is correct ...


The pressure in the return line is much less than what is needed to open the valves and there is no resistance towards the tank return.
Since both the fuel pump return and the fuel regulator have a (pressure driven) valve they really aren't at odds.
Both bleed off excess fuel into the same return line.

And off to Cars & Coffee today ... was fun to drive it .

Confess,

What type of line did you run through the tunnel?
What was the situation at the tank with no line on it from the previous setup?

He is attending the bbq aforementioned.

The PO or P - PO had been in there .
Lines at the tank through the tunnel were new (that triple layer FI hose).
The return line was there, it had just been routed to the return port on the pump only.
And the "upper part" of the system ad just been routed incorrectly.

Danger Will Robinson...!

Rubber fuel lines through the tunnel are a problem waiting to happen. Advise replacing with the SS tubing for safety.

^^^
thanks & understand .

I just needed to know I didn't have a BIGGER issue.

Now that it runs and pressures are correct and i have been able to test other components .
My winter project(1 of them) will be to do SS lines

Thanks again to all for info !

Ugh I started this one from post 1! Yikes. Good thing you noticed that! Wow that's a LOT of pressure to run through the stock system.

Hey like Jeff said, get yourself some stainless center tunnel lines. Call Chris at Tangerine Racing. He makes a nice set. Took me a matter of minutes to install mine once I pulled the tank and got the old stuff out. Never have to replace them.

Stainless Fuel Lines

Don't put it off too long!