I want to do a fuel pump volume test on my 98 Mazda 62 2L GF, but the WSM doesn't say how long to energize the injectors:

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I'll probably activate the injector by back probing the injector ground wire and then grounding it. I guess the Special Service Tool they use may have timing built in.

  • I cannot see your image, so will ask the question ... are your injectors side or top fed? The MCM guys did an injector test. They used a graduated cylinder to calculate flow through the injector. They measured the time it took to flow 100ml, IIRC. They tested each injector at this rate to see how closely they were matched and to see the spray pattern of the injector. I don't know if this is what you are trying to accomplish. Dec 6, 2016 at 14:00
  • @Pᴀᴜʟsᴛᴇʀ2 It says in the WSM to turn the injector on, measure 56-61 milliliters and turn the injector off. If not as specified, replace the injector. Doesn't make allot of sense to me. Dec 6, 2016 at 17:36

1 Answer 1


According to agcoauto.com the length of time that you are supposed to let the fuel flow is 15 seconds. In that period of time, you should have collected at least 1 pint of fuel.

However, you should also be watching the pressure to make sure it remains relatively constant. If the pressure hesitates and spurts, the fuel pump will not be able to provide a constant pressure to the engine when it is running.

  • The WSM calls for measuring 56-61 milliliters, which is way less than a pint I think. But I guess I could do something like that, and just look for variation among the injectors. Dec 6, 2016 at 17:57
  • Makes sense. 1 pint is equal to 473 milliliters. Dec 6, 2016 at 19:18
  • I don't quite understand your comment Dec 6, 2016 at 19:24
  • Sorry. Makes sense had to do with your second sentence. The equation had to do with the first sentence. Dec 6, 2016 at 19:43
  • Ahhh, the one pint refers to the total flow provided by the pump, while the 56-61 milliliters refers to the amount when the injector is held open. I'm guessing that in either case, the time is 15 seconds. Dec 28, 2016 at 14:38

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