Uno Fuel pump woes.

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Uno Fuel pump woes.

Franksuno

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Apr 29, 2017
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Had to replace the fuel pump as oil was leaking past the diaphragm seal. New pump looks identical but suddenly car just runs for a few kilometers and then suffers what seems to be a fuel flow problem. It is a 1995 Pacer with Weber Carb, built in South Africa under Fiat Licence. This problem has only arisen since the fuel pump was replaced
 
I had to Google it to see what sort of fuel pump your car has .. I'm new to Fiats..

You've got a mechanical pump, yes? Remove the pump and use a torch/mirror if need be to look inside .. you're looking for wear (usually a groove) in the cam/lobe/ring that actually operates the fuel pump arm.

The symptoms you describe fit a worn cam/lobe/ring. The arm of the fuel pump wears a groove in it, and eventually, because of the wear, won't operate.

You fit a new fuel pump and the car runs ok - because that pump is new and the tip of the arm is 'bedding in' to the groove. A few miles down the road, your car cuts out again ..

It was a very common problem with mechanical pumps. Removing the gasket between pump and block is a temporary get you home measure (it allows the pump arm to reach just a little further..). Another trick way back was to braze a dollop of metal onto the tip of the pump arm - so it could compensate for the worn groove .. but again, this was a temporary measure that only lasted a few weeks.

You can fit an electrical fuel pump somewhere in the system - there's no need to remove the old mechanical pump as the electric pump will push fuel through it.
 
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