Testing continuity and "continuity to ground"

[MORTYandrick]

I've been trying to check my fuel injector's ok- the guide says how to check continuity between the terminals - that's all fine.

But it also says check "continuity to ground"
It said with "WARNING" to disconnect the battery at the start of the chapter when dealing with anything related to the fuel system because petrol is flammable so I did so-
but in order to check the "continuity to ground don't I have to put one lead on the terminal I wish to check and the other lead to the negative
terminal of the battery?

IF I want to connect the other lead to chassis instead of negative battery terminal then surely the battery must be connected?

cheers...
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Keep it concise.

[stinkwheel]

Not really.

In most cases, there is only a single cable/strap going between the battery negative and ground, all the other companants earth through the frame. So for a continuity test, the battery need not be connected.

The answer is in the question really. You are checking "continuity to ground" and the whole frame on a bike is "ground". So you are checking for continuity between the measuring point and any piece of bare metal on the engine or frame rather than the battery negative. (the metal facing of the ignition lock is a good one. I usually stick the negative terminal of my meter in the key "gate")

A simple visual inspection will normally tell you if the battery to ground connection is good.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Pete.]

I check fuel injectors with a PP9 battery. Pull the injector, put a couple of wires on the terminals and then to the battery. It'll click and the pintle will pull in if it's working.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[MORTYandrick]

[Islander]

It suggests that the body of the injector is electrically isolated from the terminals so there is no continuity to ground from either terminal. That sounds ok to me but I'm not an expert.

However there is resistance between the terminals and that's where the current would flow - into one and out of the other. Again, that sounds ok to me.

What does the test procedure expect to find for a good injector?

Pete's suggestion for testing the injector is a good one - he knows what he's talking about.

[MORTYandrick]

Oh the paragraph I wrote was saying the tests for the fuel injector were good as described by the manual.

The main thing was: "if electrons take the path of least resistance wouldn't electrons from the negative lead of multimeter not find it easier to flow across that 1cm piece of metal back to the multimeter via the positive terminal?
yet they prefer to flow through the neg lead through the rest of chassis and away? "
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Keep it concise.

[stinkwheel]

[Islander]

[moonzoomer]

You test continuity to ground by disconnecting both terminals of the battery, for a ground connection attach one probe of your multi meter to the disconnected Negative (earth) terminal, this will allow you to test the earth connection between the batteries negative (earth) terminal and the chassis/engine for resistance. Some bikes have an earth wire to connect the chassis to the engine but most rely on the engine mounting points for a good earth but these can corrode creating a resistance which is what you are testing for. If a resistance is found by this test method the best and quickest option is to connect a cable of at least 6mm dia between the chassis and the engine to create a good earth using non corroded chassis and engine bolts as termination points.

[MORTYandrick]

Stinkwheel much love I was touching on the shiny frame was grey so I was deceived. It worked with ignition and some other bolt.
Also it says in the manual- I'll type below that shouldn't be grounded

Islander This is my injector.

The manual says:

After checking resistance between terminals (was 10.3 ohms all good as in spec) ,
Check there is no continuity to earth on the black/white terminal on the injector.
So I put the leads on those pins you see inside in the pic.
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Keep it concise.

[Pete.]

The two pins in the injector are simply either end of a solenoid pull-in coil (because that's all an injector is - a solenoid with a needle valve on the end). When you energise the coil it pulls the armature in and open the injector. I never saw one that had continuity to ground/the body and if it did then it would cause a short if it were ever wired backwards which is a hazard for a fuel system part so I doubt that there are any.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[MORTYandrick]

[Islander]

Ahem...

[MORTYandrick]

Oh my goodness, I think it's making sense now- I crawled to this point not really knowing what was going on but understanding pieces of comments.
I think I also misunderstood everything:

Stinkwheel: In the back of my mind I was thinking but "why is chassis ground it's just a piece of bloody metal" but I realise the last bit of your first post is just as important.

what you meant was:
All we want to test is connection to chassis is good.
By that visual check When we reconnect the battery to chassis- the chassis will be grounded.
By transitivity the connection to ground of everything will be good.
My last questions on this bit is:
1)
How can we visually check the battery connection to chassis is good visually without the multimeter?
2) what if you have some sort of crash and there's damage to the chassis and now some bits of go missing or something and not all of the chassis is interconnected so causes electrical issues- how can it
be diagnosed? (sorry if this is far fetched and the chassis is too solid for this to ever happen...)
3) when I have to "check the battery voltage at the black/white wire terminal in the wiring connector now the battery must be connected right?

To Islander I'm so stupid- I got mixed up with the terms the manual was using.
Could you please clarify the following is right:
1) the injector body is the first two pics
2) The injector terminals are the pins in the second pics.
3)The wiring terminal are the pins in the wiring connector in the last pic.

Assuming that's alright.
I very stupidly was connecting 2) to chassis instead of 3) to chassis because I was mixed up with 2) and 3). I really don't know what I was thinking when obviously it would infinite resistance with a disconnected injector
Oh and I also forgot to add I was supposed to be doing this with the wiring connector disconnected from the the injector.

When you were saying "It suggests that the body of the injector is electrically isolated from the terminals"
You obviously assumed the injector body was connected to the engine right?
If I had told you also I took the injector body was also removed from engine then that suggestion would not have been true would it?
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Keep it concise.

[Pete.]

Exactly what problem are you trying to fix? It sounds like you're trying to go too deeply into things that probably have no fault at all.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[MORTYandrick]

I am trying to fix nothing. I am trying to learn- these are all checks to make in the manual IF something is wrong.
Look at my profile
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Keep it concise.

[Pete.]

[MORTYandrick]

[Pete.]

No, you've basically been using up people's time on the precept that you have a problem that needs solving when in fact all you have is an idle curiosity, no problem and no clue.

[MORTYandrick]

[Islander]

To explain, people that post in this forum (Workshop) are usually looking for help with a problem rather than just trying to learn about things which in itself is creditable. We were under the impression that you had a problem with your injector.

To answer your questions though, the injector terminals are the electrical connectors on the body of the injector, the wiring terminals are indeed the ones in the connector on the loom. The injector is the injector.

You're overthinking the rest. There should be a resistance (as defined in the manual) between the two pins on the connector body. There should be infinite resistance between either pin and the metallic part of the injector. That's it.

Pete's suggestion of using a 9v battery to test operation of the injector nozzle is a quick and efficient way of eliminating electrical problems with the injector.

[MORTYandrick]

cheers very much for the answer
peace out.
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Keep it concise.

[neptune8]

Just a small point here. Stating the obvious, but the "continuity to earth test"
must be done with the injector installed on the engine!
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[MORTYandrick]

but it didn't say to check continuity to earth of the injector and that's not what I tried. it said 1) check continuity to earth of the wiring terminal of the connector for the injector. and 2) check resistance between the pins of the injector.
both were fine.
can 1) and the test you just suggested be interchanged?
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Keep it concise.

[Pete.]

Of all the things on a bike or fuel system that could go wrong, the injector must be just about last on the list. It's one of the most reliable components you could find on a bike.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good