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Thought I would share my recent experience diagnosing a fuel issue in my late model A4 on Grey Goose, a 1977 Pearson 30.
I'm pretty meticulous about maintaining my A4 and last winter rebuilt both the carburetor and mechanical fuel pump. She ran without incident most of the summer, but wouldn't start after a two-week vacation during which Grey Goose sat on her mooring through some pretty rough weather. Some quick diagnoses suggested it was a fuel issue and that some ethanol or a foreign body had clogged the main jet. I removed the carb, gave it a thorough cleaning, changed the polishing filter and the fuel line from the filter to the carb in case it was breaking down. While I was at it, I operated the priming bail with the fuel line in a small cup to verify that it was operating. I reinstalled everything and she started right up, though would occasionally stall after a few minutes unless I first primed the fuel pump using the priming bail. Hmm...
Several weeks ago, Grey Goose spent two consecutive weekends on the mooring and again wouldn't start. Frustrated, I once again removed the carb, cleaned, reinstalled -- no luck this time. Sediment bowl had fuel, but after emptying it, it wouldn't fill when I operated the priming bail. I suspected a pinhole leak somewhere in the copper fuel line from the tank to the primary filter. Called Don who wisely suggested replacing the copper fuel line and installing a rubber priming bulb between the tank and the primary filter, allowing me to prime the Racor element and pressurize the system to find any leaks. I detected a small leak at the input fitting to the primary filter and quickly took care of that with JB Weld. Primed using the rubber priming bulb and got fuel all the way to the sediment bowl. Got to be good now, right? Wrong. Removed the flame arrester - dry. No fuel. Opened the carb bowl drain - dry. <sigh> Back to the drawing board.
Next... Removed the mechanical fuel pump, wondering if there might be a leak in the upper housing where the sediment bowl is fitted (with a new gasket). Sanded it down and double checked the pump diaphragm which seemed in bad shape despite being replaced last winter. Replaced the diaphragm and gaskets, reinstalled and... nuthin @#&*(!. Removed the fuel pump (again!) since fuel was now getting to the fuel pump but not to the carb. I opened the fuel pump and found that the fuel was never making it out of the sediment bowl -- the upper housing was bone dry. I removed the two small valves in the upper half of the fuel pump and, upon close inspection, found that the intake valve was stuck closed. A quick replacement (I had purchased another fuel pump rebuild kit to replace the diaphragm, so I had the valves on hand). Reassembled, hit the priming bail and heard the sweet sound of a gush of fuel. Hit the starter and she started immediately -- success. I checked the valves' operation with a small screwdriver and found that the intake valve was almost 'glued' closed (shellaced over?). This valve was replaced less than a year ago -- I'm guessing ethanol was the culprit, but suggest anyone having fuel-related shutdowns or starting problems to check these valves. It's the size of a nickel, but cost me considerable grief. Once discovered, it took maybe 15 minutes to replace the valves, reinstall the fuel pump and carb and reconnect fuel lines.
My pain is your gain
(Of course hindsight is 20/20, but I could have done a better job diagnosing the issue. Still got to a happy ending, though)
I'm pretty meticulous about maintaining my A4 and last winter rebuilt both the carburetor and mechanical fuel pump. She ran without incident most of the summer, but wouldn't start after a two-week vacation during which Grey Goose sat on her mooring through some pretty rough weather. Some quick diagnoses suggested it was a fuel issue and that some ethanol or a foreign body had clogged the main jet. I removed the carb, gave it a thorough cleaning, changed the polishing filter and the fuel line from the filter to the carb in case it was breaking down. While I was at it, I operated the priming bail with the fuel line in a small cup to verify that it was operating. I reinstalled everything and she started right up, though would occasionally stall after a few minutes unless I first primed the fuel pump using the priming bail. Hmm...
Several weeks ago, Grey Goose spent two consecutive weekends on the mooring and again wouldn't start. Frustrated, I once again removed the carb, cleaned, reinstalled -- no luck this time. Sediment bowl had fuel, but after emptying it, it wouldn't fill when I operated the priming bail. I suspected a pinhole leak somewhere in the copper fuel line from the tank to the primary filter. Called Don who wisely suggested replacing the copper fuel line and installing a rubber priming bulb between the tank and the primary filter, allowing me to prime the Racor element and pressurize the system to find any leaks. I detected a small leak at the input fitting to the primary filter and quickly took care of that with JB Weld. Primed using the rubber priming bulb and got fuel all the way to the sediment bowl. Got to be good now, right? Wrong. Removed the flame arrester - dry. No fuel. Opened the carb bowl drain - dry. <sigh> Back to the drawing board.
Next... Removed the mechanical fuel pump, wondering if there might be a leak in the upper housing where the sediment bowl is fitted (with a new gasket). Sanded it down and double checked the pump diaphragm which seemed in bad shape despite being replaced last winter. Replaced the diaphragm and gaskets, reinstalled and... nuthin @#&*(!. Removed the fuel pump (again!) since fuel was now getting to the fuel pump but not to the carb. I opened the fuel pump and found that the fuel was never making it out of the sediment bowl -- the upper housing was bone dry. I removed the two small valves in the upper half of the fuel pump and, upon close inspection, found that the intake valve was stuck closed. A quick replacement (I had purchased another fuel pump rebuild kit to replace the diaphragm, so I had the valves on hand). Reassembled, hit the priming bail and heard the sweet sound of a gush of fuel. Hit the starter and she started immediately -- success. I checked the valves' operation with a small screwdriver and found that the intake valve was almost 'glued' closed (shellaced over?). This valve was replaced less than a year ago -- I'm guessing ethanol was the culprit, but suggest anyone having fuel-related shutdowns or starting problems to check these valves. It's the size of a nickel, but cost me considerable grief. Once discovered, it took maybe 15 minutes to replace the valves, reinstall the fuel pump and carb and reconnect fuel lines.
My pain is your gain
(Of course hindsight is 20/20, but I could have done a better job diagnosing the issue. Still got to a happy ending, though)
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