Title: Fuel starvation
Post by: Anders Dinsen on March 03, 2009, 11:26:01 pm
I don't mind telling people when they are right and I was wrong, so let me get it straight now rather than later: Krede, you were absolutely right, I should not have put my bet on the Biltema fuel pump!
It turns out that my "carburettor ice" problem was the fuel pump not filling up the float chambers. I have played with it tonight, and had it idling until it died out. In fact it slowly decreased in revs, and by lifting the starter circuit or screwing the idle mixture screws out a bit, I could keep it running for a short while until it died completely. Lifting off the lid to the float on one of the carbs, I saw that the chamber was empty!
My electronic control circuit works okay (see http://dinsen.net/murena/electrics/fuelpump ) , but the pump just does not supply any fuel into the float. Turning off and back on the igntion runs the pump fine to prime the floats, but then it just stops pumping and the car only runs until the float chambers are empty. Testing fuel pressure indicates that the pump tends to stop pumping if the pressure drops only slowly, so the pump is obviously defective :(
Fortunately, Krede has donated me his old SU pump and a fuel pressure regulator, so I'm going to have to try that out instead...!
At least I've diagnosed the problem...
It turns out that my "carburettor ice" problem was the fuel pump not filling up the float chambers. I have played with it tonight, and had it idling until it died out. In fact it slowly decreased in revs, and by lifting the starter circuit or screwing the idle mixture screws out a bit, I could keep it running for a short while until it died completely. Lifting off the lid to the float on one of the carbs, I saw that the chamber was empty!
My electronic control circuit works okay (see http://dinsen.net/murena/electrics/fuelpump ) , but the pump just does not supply any fuel into the float. Turning off and back on the igntion runs the pump fine to prime the floats, but then it just stops pumping and the car only runs until the float chambers are empty. Testing fuel pressure indicates that the pump tends to stop pumping if the pressure drops only slowly, so the pump is obviously defective :(
Fortunately, Krede has donated me his old SU pump and a fuel pressure regulator, so I'm going to have to try that out instead...!
At least I've diagnosed the problem...
