Cosworth Vega Oil Pressure Sensor - Truth or Myth?

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Cosworth Vega Oil Pressure Sensor - Truth or Myth?

Postby h-bot » Mon Mar 10, 2003 5:56 am

From: img width=12 height=12 border=0 src="http://opi.yahoo.com/online?u=bobc997615&m=g&t=0" alt=""_REMOVE_932665_THIS_@yahoo.com

Here's a question/quiz for all you guys (and gals) to ponder.
(Everyone but Jerry Smith)

- Does low oil pressure (under 4 psi) disable the fuel pumps on a
Cosworth Vega?

- What does the oil pressure switch control on a Cosworth?


See ya!


bob chin




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Cosworth Vega Oil Pressure Sensor - Truth or Myth?

Postby h-bot » Mon Mar 10, 2003 6:05 am

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Unlike the 140 Vega, the oil pressure switch on the CV is not wired
into the fuel pump circuit to disable it when low oil pressure is
detected, though this is a popular myth.

The 140 Vegas have a three pin oil pressure sender that is wired to
both the fuel pump circuit and the oil pressure light. The CV oil
pressure sender has only two wires and only operates the warning light
in the instrument cluster. The CV oil pump circuit originates in the
ECU and is compeletly independent of the oil pressure circuit.

All this can be verified by analyzing the CV wiring schematics in the
shop manual supplement.

Duke






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Cosworth Vega Oil Pressure Sensor - Truth or Myth?

Postby h-bot » Mon Mar 10, 2003 7:27 am

From: img width=12 height=12 border=0 src="http://opi.yahoo.com/online?u=rockken_cosworth&m=g&t=0" alt=""_REMOVE_155701_THIS_@yahoo.com

"The CV oil pump circuit" --I believe you meant "fuel"

I remembered correctly, but just didn't post fast enough.
It is interesting that the 140 vega had this fuel cutoff
fail safe built in, yet the Cosworth did not. I suppose
the extra engineering within the ECU was not worth the cost.
Funny they just did not use the existing 140 sensing unit though.
Perhaps the 2 lead unit was used elsewhere in GM.

I beleive on some of our cars we have replaced the sending unit
with a pressure guage fitting, yet I feel that the light coming
on in the dash is beneficial for the "LOOK AT ME QUICK" factor.
perhaps a TEE fitting is best there.

I wonder if it would be feasible to put a switch inline with the
pump wires to add the fuel cutoff feature. The solution is not
that simple, however, as one would have to deal with the case where
the key is turned on and the HP pump is activated breifly to
pressurize the fuel system, at least for fuel injected cars. Webers
would run for quite a bit longer with fuel in the bowls. I imagine
the switch would have to interrupt the ignition in that case.

Any other thoughts?

Ken




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Cosworth Vega Oil Pressure Sensor - Truth or Myth?

Postby h-bot » Tue Mar 11, 2003 1:08 pm

From: img width=12 height=12 border=0 src="http://opi.yahoo.com/online?u=bobc997615&m=g&t=0" alt=""_REMOVE_800376_THIS_@yahoo.com

--- In <a href="/group/cosworthvegas/post?protectID=219233066105193209050199029077192253163098100009128121188190230091025019053061151110147">cosworthvegas@yahoogroups.com</a>, "Kenneth Rock"
<<a href="/group/cosworthvegas/post?protectID=051056234185056134170082189036209063098032044109209130152">Kenneth.M.Rock@B...</a>> wrote:

> I remembered correctly, but just didn't post fast enough.
> It is interesting that the 140 vega had this fuel cutoff
> fail safe built in, yet the Cosworth did not. I suppose
> the extra engineering within the ECU was not worth the cost.
> Funny they just did not use the existing 140 sensing unit though.
> Perhaps the 2 lead unit was used elsewhere in GM.
>
> I wonder if it would be feasible to put a switch inline with the
> pump wires to add the fuel cutoff feature. The solution is not
> that simple, however, as one would have to deal with the case where
> the key is turned on and the HP pump is activated breifly to
> pressurize the fuel system, at least for fuel injected cars.
Webers
> would run for quite a bit longer with fuel in the bowls. I imagine
> the switch would have to interrupt the ignition in that case.
>
> Any other thoughts?

If you carefully look at the Vega electrical schematic. It doesn't
take long to see that the Vega & Cosworth front harnesses are not
interchangeable.

The interesting thing about the Vega is why it uses a 2 prong sending
(Cosworth uses a single prong)unit. The Vega circuit, thru the
igniton switch, in "start", uses one side of the switch so the fuel
pumps will run with "zero" oil pressure. Once in "run", the circuit
uses the other side (pressure) of the sending unit, to control the
fuel pumps and dash light.


bob chin
>
> Ken




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