How to measure 3.4oz per minute?

[TexasCoder]

Hey gang!

So, I gotta get the ol’ 2005 Honda Metropolitan scooter ready for the upcoming spring…I can see the gleam and excitement in my wife’s eye, as warmer weather approaches. Which translates into “Daddy better have that thing ready, when mamma is ready to ride” T)

I noticed this morning, as I like to start it every once in a while, that it would not start (Crank with No Start). The battery is on a trickle charge, and was full of juice, the starter turned over just fine. I did not have time to check for spark and fuel delivery, but I did grab my Honda service manual, as I was headed out the door for work.

While reading this morning, I am jotting down notes on what to check, one of the items is the fuel pump displacement. Here are the steps to testing output, and if the pump needs to be replaced:

1) Turn the key to the off position, flip the run switch to off.
2) Disconnect the fuel hose from the carburetor, put the hose into a measuring cup.
3) Turn the key to ON, flip the run switch to “Run” (upside down U arrow), let pump run for 5 seconds, turn key OFF.
4) Take the amount of fuel in your container and multiply it by 12.

If it is anything under 3.4 oz per minute, then you need to replace the fuel pump.

I plan on checking other items: spark, fuel filter, needle jet clogged…then on to to electrical (ignition switch, coil, fuses) and basically on down the line till I find the problem(s).

My question, how the heck do I measure exactly 3.4oz? Anyone know of any containers (chip dips, soda bottles…) that are exactly 3.4oz? Or should I just find something “close enough”?

Topic

[yarddog1950]

3.4 oz divided by 12 = 0.283333 oz
Five seconds of fuel is very little and you may not have any way to measure it.
You could get 30 seconds of fuel. That would be 3.4 oz divided by 2 = 1.7 oz.

Still, check for clogged fuel lines and so on. The fuel pump is probably just fine.

[TexasCoder]

Good point yarddog1950! Great eye on reading those instructions, I went back and read them for a second time, and now understand what the instructiosn really want. I was confused on the 3.4oz at 5 seconds, but that is not the case.

I plan on going through the list of things to check, I imagine it is a couple of things, for years now I have been good about putting sta-bil in the gas when I knew it was going to sit for longer than 30 days. And I always go out and start it up once a week to let it idle, and if not too cold or wet outside take it down the street.

But I agree, I will check the basics first and report back what I find!

[spelunkerd]

You’re trying to answer a ‘crank no start’ problem, aren’t you? At this point, getting so deep into the technical aspect of exact fuel volume delivery is missing the mark. A pro wouldn’t do that first. Also, low volume might mean a clogged fuel filter, so I wouldn’t jump to the conclusion that it is a bad pump even if flow is a little down. Finally, if it isn’t even starting, then the fuel delivery won’t even be close to 3.4 oz.

If you think it’s poor fuel delivery, spray some quick start into the carb and see if it starts, then dies as the quick start disappears. If it does, then it is either bad gas, a dirty carb, or poor fuel delivery to the carb. When you are talking about a bike that is used infrequently, bad gas is more common than you might think. Sure, you could disconnect the fuel line and see if it spits fuel, but I wouldn’t worry about calculating volume unless very little fuel spills into the cup. If it starts with quick start then I would replace the gas, clean the carb, and change the fuel filter and see if it starts then.

[SpawnedX]

Your local Wal*Mart should have a measuring cup with both ounces and cups on it.

[TexasCoder]

Quoted From SpawnedX:

Your local Wal*Mart should have a measuring cup with both ounces and cups on it.

Good point, you think they would carry something that would hold exactly 3.4oz or show the lines for .4 oz or if the test shows 3.0oz – 3.5oz I should call it good?

[SpawnedX]

Quoted From TexasCoder:

Good point, you think they would carry something that would hold exactly 3.4oz or show the lines for .4 oz or if the test shows 3.0oz – 3.5oz I should call it good?

Probably not, you are going to have to eyeball it, 4 oz is half a cup, so 1 oz is 1/8 cup, 3.4 oz is .425 cup and 3/8 cup is .375 a cup, so you need somewhere between 3/8 and 1/2, slightly higher than halfway between it.

[SpawnedX]

You could also try to do it by weight, which I am not necessarily recommending, but it is possible. Measure the weight of the container you let the fuel pour into empty, then measure the container after you let the fuel pour in.

There should be a change of approximate 0.15725 lbs or more for 3.4 ounces of fuel, problem is, the ethanol content of the fuel changes it’s specific gravity, so those numbers aren’t exact.

[TheArete]

I agree with SpawnedX you are probably going to have to do a little bit of Eyeballing. I was going to suggest weighing it but that requires knowing the specific gravity of what liquid you are weighing… but that would be a long and drawn out way to figure out something simple.

My suggestion… pick up a a glass graduated Beaker or cylinder for around ~8 bucks. You can buy one on Amazon, and measure ACCURATELY your gasoline that way.

Or go to Walmart… pick up a measuring cup and a tablespoon. A Tablespoon is about .5 ounces, so 8 tablespoon and you’re at 4 oz. 9 tablespoons and you are at 4.5 oz. A teaspoon is about 1.67oz just for comparison.

So if you let it run out into a graduated cylinder or into a measuring cup you can then Tablespoon it out into another container… if you’re about 9 tablespoons or more then you’re pump is producing appropriate amounts of gasoline… less and then you’re in trouble.

Just Make sure you measure at the bottom of the meniscus for the most accurate measurement of a graduated cylinder or beaker (though it most likely is too minute of a difference to really matter).

I’d check your plugs, wires, etc… first though. Good Luck!

[college man]

I don’t think 4oz vs 3.4oz will hurt the test. if anything it pumped more.

[yarddog1950]

If you follow the instructions, you will need a container that measures 5 seconds of fuel, NOT one minute.
If you run the fuel pump for 5 seconds, measure the collected fuel AND multiply by 12, you get 3.5 oz of fuel.
(Was that 3.5 or 3.6 oz ?)
Anyway… If you have 5 seconds of fuel, you should have 1 minute of fuel divided by 12.
If you have 10 seconds of fuel, you should have 1 minute divided by 6.

Here’s what I would do. Check to see if you have fuel flow. Don’t measure it. If it’s flowing, even if it’s not enough, the scooter should start and idle.
If it’s dripping or not flowing, check for clogged lines, smell the fuel in the tank to see if has turned to varnish. This is more likely to be the problem than a bad fuel pump because bikes left to sit for a while sometimes get this fuel problem.

If you have a fuel problem, it’s likely to affect the whole system, the tank, the lines, the carburetor. You may find it easier to check for spark first. (Or did you do that already?)

[ytram]

Did not have time to read all the responses, so sorry if this is redundant.
1000 ml/128 ounces a galon = 7.8 ml per ounce.
3.4 ounce x 7.8 ml = 26.52 ml
26.52 ml /60 seconds = .442 ml a second.
So round off to aprox. half of a ml per second. Hope that helps.

[Author]

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