The Ford Barn

john charlton · 06-18-2019, 08:35 AM

On idle my P/U will not fire on no.4 cylinder .I checked the compressions on the engine cold . 1,2,3 are all spot on 60lbs . No 4 is 65 lbs which I guess could be that caused by unburnt residue in the cylinder/rings etc . I have changed the plugs around,changed the manifold gasket,checked all points gaps are correct and even .Changed the distributer cap . When I short out no 4 with a screwdriver I have a hefty spark the same as the others . I thought maybe an airleak in the manifold but no 3 shares that, it fires fine . On idle I have enriched the GAV but no change . What am I missing ??? I need a logical explanation !!! When at highway speed it runs on 4 and pulls fine maybe I worry too much !!! Keep on driving what the heck but still it bugs me .

John in cloudy mild rain on the way AGAIN Suffolk County England .

06-18-2019, 08:35 AM	#1
john charlton Senior Member Join Date: May 2010 Posts: 1,304	Mystery Missfire On idle my P/U will not fire on no.4 cylinder .I checked the compressions on the engine cold . 1,2,3 are all spot on 60lbs . No 4 is 65 lbs which I guess could be that caused by unburnt residue in the cylinder/rings etc . I have changed the plugs around,changed the manifold gasket,checked all points gaps are correct and even .Changed the distributer cap . When I short out no 4 with a screwdriver I have a hefty spark the same as the others . I thought maybe an airleak in the manifold but no 3 shares that, it fires fine . On idle I have enriched the GAV but no change . What am I missing ??? I need a logical explanation !!! When at highway speed it runs on 4 and pulls fine maybe I worry too much !!! Keep on driving what the heck but still it bugs me . John in cloudy mild rain on the way AGAIN Suffolk County England .