method for verifying fuel pump output volume

F

fsacht

Member
Vehicle in question is a '42 Mercury. The spec is one pint in 45 seconds at idle speed. It seems to me that it's a two person operation. One to feed fuel to the float chamber and the other watch the clock and be sure the empty test receptacle starts receiving fuel at start time and is shut off at 45 seconds. Have any of you run this volume test and what set up and or system did you use to keep the test accurate?
 
How about this. Disconnect the fuel line from the carb and direct it into a suitable recepticle (you may have to use a length of rubber hose). Crank the engine with the coil wire pulled for 15 seconds. Measure the amount of fuel pumped and multiply by 3. It should get you close.
 
What if you connect a fuel tank that is placed higher than the carburettor, directly to the carburettor, and connect a longer hose from the fuel pump to a container that you can measure the fuel pump output?
Just start the engine and let it idle?

Rune Waltoft from Norway
 
Rune William Merc,
Your system is where my thoughts were going. How to suspend or provide a fuel source higher than the carb inlet is a puzzle. A second hand will fix that. Your suggestion satisfies the requirement of operating at idle speed whereas cranking speed does not, so your findings would be of value. Assuring that the only fuel entering the test receptacle is that which entered it during the test time at idle speed is the last obstacle. Thanks .... Merc.
 
engines will idle just fine using a spray / mist bottle stolen from your wife. start it up and run with whats in the float bowl, and you may not even need the spray bottle
 

Attachments

  • b3228cfc287102b9e104434fbc01f1cf.jpg
    b3228cfc287102b9e104434fbc01f1cf.jpg
    12.1 KB · Views: 9
Started this thread because was trying to isolate a steady regular miss while in second gear about 20 mph. Sound and feel was fuel starved but chock had no effect to improve miss. Satisfied fuel pump performance and while reinstalling the fuel tube to engine discovered that the tube nut at the carb end has a crack that runs from the compression ferrule to the hex of the nut. I'll install a new tube and see if that is the root cause.

Thanks to all for the helpful suggestions.
 
Installed new tube with new compression fittings this morning and the miss is gone and it's driving smooth, 59397 original miles.
 
fsacht said:
Started this thread because was trying to isolate a steady regular miss while in second gear about 20 mph. Sound and feel was fuel starved but chock had no effect to improve miss. Satisfied fuel pump performance and while reinstalling the fuel tube to engine discovered that the tube nut at the carb end has a crack that runs from the compression ferrule to the hex of the nut. I'll install a new tube and see if that is the root cause.

Thanks to all for the helpful suggestions.
Click to expand...


Don't know if you have a glass filter bowl, but if so, a cracked or loose bowl gasket will cause similar symptoms by sucking air.
 
You must log in or register to reply here.
Back
Top