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Stock '71Z fuel return line


JessZ

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I'm in the process of a L28et swap into my '71Z. I've mounted and hooked up my fuel pump, and reused the original metal gas line going to the injectors. My question here is, will the smaller RETURN line that originally came on my Z be sufficient for the higher volume gas flow back into the tank?

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Well, I did the swap in a 71 also and I replaced both lines with big diameter ones. When the engine is running, if I crawl under the rear of the car and touch the lines, the return line is very hot. I would assume that if I had used the original small diameter lines the fuel will get hotter. Additionally, if the original lines are obstructed in any way (since they're the original ones) then fuel will get even hotter!!!! I would be having vapor lock for sure. I had vapor lock back when I had the stock carbed engine, so that's why I changed the lines in the first place.

 

So, I would recommend not using the stock fuel lines, it's not worth the trouble (you don't want fuel delivery problems under boost).

 

Also, if you're using the stock fuel tank you should change the inlet and outlet pipes, since the stock ones are very small.

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I'm in the process of a L28et swap into my '71Z. I've mounted and hooked up my fuel pump, and reused the original metal gas line going to the injectors. My question here is, will the smaller RETURN line that originally came on my Z be sufficient for the higher volume gas flow back into the tank?

 

Absolutely. I ran my L28ET for years at high boost with the stock lines. Don't waste your money unless you plan on over 500rwp.

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Your pressure will be very high at idle if you are running a 255l pump using the stock return. You could do it using a smaller low volume pump but why? I used the emissions hard line for a return line. It is a little larger that the fuel return line and can handle more volume. My idle pressure is still a few pounds higher than it should be but it works.

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:sour: I just hooked up the pos. wire to the fuel pump and it's leaking. The neg. is not hooked up. Is this somehow, please, from the neg. not being hooked up? Or is it simply the obvious---the I need a fuel pump.
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Your pressure will be very high at idle if you are running a 255l pump using the stock return. You could do it using a smaller low volume pump but why? I used the emissions hard line for a return line. It is a little larger that the fuel return line and can handle more volume. My idle pressure is still a few pounds higher than it should be but it works.

 

Nice suggestion.

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:banghead: The fuel pump was up-side-down and the lines were not connected tight enough. Man, I am in over my head with this swap. I have to move to S.F. this Sunday as my girlfriend starts her new job on the 24th of July. I am truely at my wit's end with this wiring thing too. I should have just stuck with carbs.......... Too bad I sold them........... Lazy eyed and beat to a pulp sigining off.
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Hey JessZ, I know how you feel. Ive been there with my Carbs to EFI swap, but its all starting to come together, as Im sure yours will. If youre moving to San Fransico, I live real close, maybe I can lend a hand if you need it. I also still have my set of tripple Webers if you really decide to go back to carbs and want a nice setup.

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Thanks for the offer. I spent some time today on my wiring and was able to get my ECU turned on, as well as my fuel pump. Actually, I have everything hooked up, but I am not able to get ignition, spark, or something. It's too late to deal with it now as my battery died. Anyway, if you have adivce for a 240ZXT I'd sure be grateful. Thanks again... Jesse

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I just did my turbo swap this last weekend. The coil wires are easy.

Look at this page.

http://www.strausz.us/zcar/turboswap/

 

Here is that guy's wiring drawing

turbozxwiring.gif

 

On the 8 plug connector just up from the ECU that doesn't go to anything I only hooked up one wire.

The Yellow with white stripe wire (the one closer to the black wires, I marked it yellow on the pic above) goes to the yellow with white on the coil harness. You do have the coil harness from the turbo Z, right? The black with white strip on that is power, the blue is ground. Splice your factory coil's + and - to the black and blue wires on that turbo harness. Those three total connections are all you need there. If you got the ECU to turn on, and the fuel pump on, you're set!

 

It helps if you have the other end of that plug from the turbo dash harness. I grabbed that part so I spliced off the back end of that plug and then once it was wired into my coil wires, I just plugged it in. But without it, you can still just plug a single wire in to the correct spot and then tape it up good so it won't pull out.

 

As long as you oil pump was installed correctly so your ignition timing is right, you should be good for a drive.

 

the other funky connectors by the coil are for the factory boost sensor which sends a signal to the boost gauge. You do not need that for the car to run. The ECU does not detect boost at that point.... does it even detect boost at all? is a very simple ECU

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No gas from injectors and no spark from coil.

 

 

Well the ECU does turn on, and the fuel pump is pumping gas, but still nothing. In fact, when I pull the spark plugs I can tell by smell and touch that there is no gas being sprayed by the injectors. Something else I noticed was that the coil does not seem to be producing any spark. When I pull the coil plug to the distributor, ground it to metal, and start the car there is no spark. Could the coil be bad? I've never had a bad coil so I want to doubt that that is the problem.

 

Anybody want to call me? 805 550 4149, names Jesse.

I am moving to S.F. Sunday and need to get this car rolling.

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try to manually switch 12v on and off to the coil while someone holds the coil output wire near gound. you should get a spark every time you disconnect the 12v from the coil (assuming the wire is close enough to ground). that will give you an idea if the coil is working at all.

As far as the indectors go, if you hit them with 12v really quick, do they open? if so, pull them out and see if they are spraying gas when you open them by applying 12v, or if there is any pressure at all behind them.

 

good luck, I hope this all made sence to you, but its 130am and im tired :S

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I had marked the wrong wire above. As I stated in my post above, it is the yellow with white stripe but I had marked the yellow wire as the one to connect. the picture has been corrected.

The other wire he says to hook to ignition I had tried hooked to power and also not hooked up at all. the engine runs both ways. (although my engine has some problems under boost still)

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