280Z Fuel Lines

[sblake01]

Yeah, you've got to drive them at least once every couple of weeks.

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I noticed in the FSM (factory service manual) that it shows using all metal tubing on the high pressure side, to be "butted end to end" with just Fi hose overlapping the splitline between the the tubing. This is a much stronger line than just FI hose only and does not allow hose fluctuation from pressure variances.

[TomoHawk]

Definitely use only F.I. rated fuel hose on the high pressure side.

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I found that my return line had to be restricted to compensate for the vacuum leak I found in the EGR system, using the propane method I finally found it under the EGR cap around the valve bellow.

Using a flow control needle valve fuel pressure was boosted and the car RAN GREAT! Open the line to a normal 36 psi and ran crappy especially at start up when cold.

So I basically I need to fix this ? why it is opening when it should be closed, ? not being controlled, or ? just plain leaking through.

good support

[Walt76280Z]

Keeping an old thread going with a new wrinkle....

My '76 w/ EFI has the 'stumbling start' symptom (better than calling it vapor lock, right ) It is more akin to the April '07 post on this subject as the condition exisits when it is heat soaked only. It goes away after 15 seconds of 1/4 throttle.

I have a Nissan remanufactured F54/ P79 with 1700 miles on it, along with a reconditioned 280ZX fuel rail, new '77-'83 injectors, new 280ZX fuel pressure regulator, and new wiring harnesses (a la Z31 recall). BTW, the fuel tank interior was fine... it was inspected as was the fuel pump while the engine job was in progress.

I checked the charcoal cannister, cleaned the filter out (it was dirty, but not absolutely covered), and cleaned and blew air through the nipples. I was able to blow air through the return line back to the fuel tank (after momentary resistance).

I'm a little confused since I never had this symptom with the old N42. I'll look into the check valve and have a pressure test performed. I'll post an update later.

[mazingerz1976]

Karlb i would like to know if you solved your problem and how?, i have experienced something similar and could not solve it ....

[Walt76280Z]

Sorry it took so long.... had an unexpected operation in December. Back on track now.

I finally ran a fuel pressure test today. When throttle was applied, the system rose to 36 PSI.... then promptly collapsed. Pulled vacuum from the regulator, and pressure rose as expected. It went right back in check when vacuum was reapplied.

Shut the car off. 20 minutes later, pressure was at 31 PSI. One hour later, 26 PSI.

Looks like a weak fuel pump needs to be addressed based on the collapse under throttle. The pump was cleaned and inspected last summer, so I'm pretty sure the screen is still clear.

I'm putting a new pump in and then back to testing.

[Walt76280Z]

New Pump in. 30-31 psi at idle, 36 under throttle.

Same condition..... :tapemouth

Next- insulating fuel rail.......