260Z Fuel delivery problem - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 5 (permalink) Old 03-20-2017, 03:36 PM Thread Starter
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260Z Fuel delivery problem


I have a 74 260Z complete stock. I've been replacing suspension part, seals, hoses, gas tank cleaning.and other aging parts. I rebuilt the flat tops and at first they seemed to be working good (in the garage) as I performed other work. I should also mention I had this care stored for about ten years.

My current problem is that while idling and low revving in the garage it runs great. When it take it out on the road for a drive the fuel level in both float bowls drops and will fill back up at idle.

I will be tearing into the fuel system in a few eeks and wondering if anyone has had the same problem.
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post #2 of 5 (permalink) Old 03-20-2017, 06:12 PM
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fuel line rust?
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post #3 of 5 (permalink) Old 03-20-2017, 06:49 PM
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I didn't read anything about replacing fuel filters either. There's one by the electric fuel pump and possibly one in the engine bay.

Tucson, Arizona

9/74 260Z VIN RLS30 060061
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post #4 of 5 (permalink) Old 03-20-2017, 09:53 PM
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dirty fuel lines, filters, and tank pickup screens are my first guess, closely followed by fuel pump problems. You have two fuel pumps...an electric by the tank and a mechanical one on the engine. The electric pump runs only during the starting of the car; it's to prevent vapor lock. If it gets clogged up and fuel can't flow through it easily, you get the results you describe. Also...you can try installing a cheap fuel pressure regulator on the return line going from the fuel line back to the tank. Spectre is the brand I used.

73 240Z very orange
Dual Weber DGV's, header and 2.5 exhaust
Electronic dizzy with G.M. HEI module
Tokico Struts/Springs, Full Poly U bushings
Daily driver, all work done by me
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post #5 of 5 (permalink) Old 03-31-2017, 11:09 AM
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The stock 1974 260's had two fuel filters, at least the late model builds did. One filter is inside the rear electric fuel pump and one inline filter is right beside the rear fuel pump. No under hood filters on stock car. The 'final' filter is inside on the banjo bolt in the carb fuel bowl. These are super fine and can even be deteriorated at this point in time.As the original owner of a 260, I can say that my car has always been very, very sensitive to clogged filters!

74 260Z 2+2, 2009 370Z Touring/Spt 6MT
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