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Discussion Starter · #1 ·
Hi, I have a stock fuel pump in my 280zx and I wanted to upgrade it so it primes faster. Does anyone know the specs on the stock one?(pressure, flow rate, etc)
 

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1983 280zx n/a 5-speed t-tops
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FSM has 12v 5.1amp cutoff pressure 43-64psi. Doesn't say anyting about flow rate. I saw a Bluestechtip that someone posted a volume test. The pump should deliver 1 liter in 30 second, but I it doesn't say where that info originated. https://atlanticz.ca/zclub/techtips/fuelpump/index.html

I know theres a formula to figure the requirements of the engine using injector flow rate and rpm - somewhere on google.

Have you checked your current fuel pressure to see if the pump and pressure regulator are within specs?
 

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Does it not fire up right away when you hit the key?

If not maybe the cold start injector, regular injectors, or the check valve may be leaking.

I’m always amazed at how fast my ZX will start when everything is working well.


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Discussion Starter · #4 ·
Does it not fire up right away when you hit the key?

If not maybe the cold start injector, regular injectors, or the check valve may be leaking.

I’m always amazed at how fast my ZX will start when everything is working well.


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it takes like 5-10 secs on a cold start and it's lowkey annoying so I can deal with it but I want something faster yk?
 

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if you think your stock fuel pump is going bad, you should replace it with another stock NISSAN OE fuel pump. they are still out there from Nissan. That pump is more than enough to properly prime your system. The function of the pump matches the requirements. If your car does not start within a couple seconds at most (and that is after a long period like weeks) then there is something else wrong, assuming the stock pump is ok.
IIRC the stock pump is calibrated to prevent excessive pressure (bleeds back) in the system. I would think this is both a safety thing and also takes a bit of the strain off the FPR. Again IIRC after market pumps have pressures that can exceed 90psi way more than needed.
One last thing to consider, If the pump fails you are dead on the street. Frankly I trust the quality of the Nissan pump over an aftermarket (at least the ones you commonly find at most auto supplies that run about 1/3 the cost of the Nissan).
 

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I guess what I was trying to say was if you are loosing your prime, you have a leak. Possibly at one of the items I mentioned above.

Have you diagnosed this with a fuel gauge?


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Hi, I have a stock fuel pump in my 280zx and I wanted to upgrade it so it primes faster. Does anyone know the specs on the stock one?(pressure, flow rate, etc)
Who told you that the OEM pump is inferior? Prime? Try testing your cold start injector.
 

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Agreed, the comments above about diagnosing root cause analysis for the extended cranking time, the stock Nissan pump is a great performer when I looked at the specs a while back it could supply 3-4 L28’s running Full rich, check valve, leaky injector, regulator,cold start injector not giving a “prime”. then there’s the coolant temperature sensor not sensing that the engine is cold…..basic diagnosis skills/FSM.
 
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