Leaking power valve and HC

Shop tells me high HC (480ppm) at idle caused by leaking power valve and bad
cat. I can understand the cat but isn't the power valve inoperative at idle?
I just disassembled the carb and cleaned but could see no problems. Car is
1980 ford 4.2l 2bbl

The power valve does not operate at idle. High HC is usually cause be an ignition miss and/or a bad catylitic converter.

Martik wrote:
>
> Shop tells me high HC (480ppm) at idle caused by leaking power valve and bad
> cat. I can understand the cat but isn't the power valve inoperative at idle?
> I just disassembled the carb and cleaned but could see no problems. Car is
> 1980 ford 4.2l 2bbl

--
Mike Walsh
West Palm Beach, Florida, U.S.A.

"Mike Walsh" > wrote in message
...
>
> The power valve does not operate at idle. High HC is usually cause be an
> ignition miss and/or a bad catylitic converter.
>
> Martik wrote:
>>
>> Shop tells me high HC (480ppm) at idle caused by leaking power valve and
>> bad
>> cat. I can understand the cat but isn't the power valve inoperative at
>> idle?
>> I just disassembled the carb and cleaned but could see no problems. Car
>> is
>> 1980 ford 4.2l 2bbl
>
> --
> Mike Walsh
> West Palm Beach, Florida, U.S.A.

Even if it's leaking? Is that the same thing as the enrichment valve . It's
a motorcraft 2150 and the valve is screwed to the bottom of the carb.

"Martik" wrote

> >> I just disassembled the carb and cleaned but could see no problems. Car
> >> is
> >> 1980 ford 4.2l 2bbl

> Even if it's leaking? Is that the same thing as the enrichment valve . It's
> a motorcraft 2150 and the valve is screwed to the bottom of the carb.

Did you take the power valve out to inspect it? How was the diaphragm?

At idle, the high vacuum signal keeps the valve closed. When you stomp
the gas, the low vacuum allows the valve to open under spring pressure.

If the diaphragm is split or leaky, the valve will open since it can't hold the
vacuum, AND fuel can be sucked directly through the leaky diaphragm into
the intake.

The power valve is the same as an enrichment valve. Regardless of the condition of the power valve, there will not be any fuel flowing through it at idle unless the fuel level in the fuel bowl is too high or the choke is stuck closed. That would give you a rich mixture resulting in high CO.

Martik wrote:
>
> "Mike Walsh" > wrote in message
> ...
> >
> > The power valve does not operate at idle. High HC is usually cause be an
> > ignition miss and/or a bad catylitic converter.
> >
> > Martik wrote:
> >>
> >> Shop tells me high HC (480ppm) at idle caused by leaking power valve and
> >> bad
> >> cat. I can understand the cat but isn't the power valve inoperative at
> >> idle?
> >> I just disassembled the carb and cleaned but could see no problems. Car
> >> is
> >> 1980 ford 4.2l 2bbl
> >
> > --
> > Mike Walsh
> > West Palm Beach, Florida, U.S.A.
>
> Even if it's leaking? Is that the same thing as the enrichment valve . It's
> a motorcraft 2150 and the valve is screwed to the bottom of the carb.

--
Mike Walsh
West Palm Beach, Florida, U.S.A.

On Thu, 14 Apr 2005, Martik wrote:

> Shop tells me high HC (480ppm) at idle caused by leaking power valve and
> bad cat. I can understand the cat but isn't the power valve inoperative
> at idle?

Sure...unless it leaks!