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Re: 4500RPM ceiling

To: datsun-roadsters@autox.team.net
Subject: Re: 4500RPM ceiling
From: Thomas Walter <twalter@austin.rr.com>
Date: Sun, 18 Nov 2001 22:47:47 -0600
Mike,


One thing that does come to mind is the "replaced the
fuel pump" then you noticed a problem! Hint, it is
NOT the fuel pump. <grin>

Since you have an early '68 2000 with that glass float
bowl, you might want to bypass the fuel filter with
a plastic one for the time being and see if you get
an improvement in performance.

Those original fuel filters are a neat period item,
but always found the cork gasket would dry out after
storage. With an electric fuel pump, mounted by the
tank, it helps by keeping the gasket wet. If there is
a slight air leak, the fuel filter will fill up to the
top, getting the gasket wet. Once the gasket is
damp, it will swell and seal.

With a manual fuel pump, the filter is now a "suck
through" style. The vacuum will cause a leaking seal
to get sucked into the fuel line at higher rpm. Probably
fine at idle, but once opened up under full load... it will
not keep up with the fuel demands.

On my 67 2000... it was cutting out around 3,500 rpm.
The wire to the ignition points had failed due to fatigue.
The insulation hid the break, but it would die out at
high rpm. Finally ran a wire from the distributor to
ignition coil directly. No more problem on that one.

Now on that pesky 68 2000 I used to own...
<just kidding!>

Cheers,

Tom Walter
Austin, TX.






> Subject: 4500RPM ceiling
> 
> 
> 
>>Seems like I remember a thread awhile back when I did
>>not own a 2000 and was not very interested, about some
>>folks encountering an accelleration dead spot at 4500
>>RPM's.
>>
>>I had my 2000 out today for a spirited test drive
>>after some tune up, and replacing the obnoxiously loud
>>electric fuel pump with a manual fuel pump.  Seemed to
>>be running well with the manual pump, but I was dying
>>at about 4500 RPM's.  I do not remember this before.
>>
>>Is there a common cause, (eg., carb richness, timing,
>>valve float, manual fuel pump) specific to the 2000?
>>
>>I also had my sweet, but slower 1600 out today, and at
>>5500 she was still winding strong.  (just not the same
>>result...)
>>
>>brain pickin'
>>
>>Mike Harper
>>'66 1600
>>'68 2000
>>Charleston SC

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