The formulation thing makes sense. If they are running MBTE it is an oxygen
enricher for gasoline and would displace the gasoline so it's less bang for
each ounce which is why you get worse gas mileage using it.
Makes sense but . . . that still leaves me with a problem I have to fix.
It definitely runs lean under steady throttle yet it's rich under
acceleration and idle.
----- Original Message -----
From: "Marc Sayer" <marcsayer@home.com>
To: "Datsun Roadster List" <datsun-roadsters@autox.team.net>
Sent: Friday, June 01, 2001 2:34 PM
Subject: Re: Runnin Outta Gas
> Its the needles. The profile is not right for the engine and at steady
throttle
> you are going lean. Since it does not lean out on hard acceleration (which
is
> enriched by the damper), it is not a fuel feed problem, which is the only
other
> thing that could cause this. Just to be sure, check your fuel pressure and
float
> level settings, but I'll bet they are within specs.
>
> Lots of folks are starting to run into a lean-out condition like this,
even with
> a stock engine and new stock needles. I am not sure why. We miked several
new
> needles to see if they were different from the older versions and they
were
> identical, within tolerances. Same engines, same carbs, same needles, but
now
> the cars are running lean??
>
> All I can think of is that something they have done to the gas is causing
the
> problem. I know that on my FI cars a change in gas formulation is very
> noticeable. When I drive down to SoCal, my cars always run worse on CA gas
than
> they do on the OR gas. We get a different formulation up here. So I am
wondering
> if one of the newer additives, like say the MBTE or other "oxygenators" is
> causing the fuel to act "leaner" somehow. Any chemists on the list that
want to
> try and answer this? Anyone else got any ideas?
>
> Nathan Ruffcorn wrote:
> >
> > Mike-
> > I have always experienced the same problem on my 2L (N17 needles). Mine
> > will keep power while aggresively accelerating, but if I hold a steady
> > speed, it tends to surge. I hate to do this, but if I'm on the highway
I
> > pull the choke out part way. You may try this as it will help determine
if
> > you are truly getting enough fuel. The choke cleans it right up, but I
hate
> > the chance of running too rich and washing my cylinder walls. I've
> > experimented with richening the carbs dramatically, but I get the same
> > result (also required radically increasing idle speed setting to run-not
too
> > practical). At first I thought the needles were causing the lean
condition,
> > now I'm not so sure. Any thoughts?!
> > BTW, manifold vaccum is good through all RPM's.
> >
> > Nathan
> >
> > ----- Original Message -----
> > From: datsunmike <datsunmike@nyc.rr.com>
> > To: Datsun Roadster List <datsun-roadsters@autox.team.net>
> > Sent: Thursday, May 31, 2001 8:08 PM
> > Subject: Runnin Outta Gas
> >
> > > Well I finally took my car out for a spin and it was great! I haven't
> > driven
> > > my car in over a year and I forgot what it felt like.
> > >
> > > While the car generally runs well I have no power above 4K RPMs. It
feels
> > > like it's running outta gas. I have 2L carbs with N17 needles and
one1/4"
> > > fuel line supplying both carbs from the Facet electric fuel pump to
the
> > > carbs. Do you think this could be the problem? I am not running lean
as if
> > I
> > > richen it my idle deteriorates.
> > >
> > > Thanks for any help you can provide.
> > >
> > > Mike
>
> --
> Marc Sayer
> 82 280ZXT
> 71 510 2.5 Trans Am vintage racer
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