Ignition coil

[steveko]

Anyone know what there coil is putting out voltage wise.Out of the blue wire that feeds down too the fuel pump relay.Also, if possible check it while running. Mine is 11.5 volts. Seems a little low.

[itzdave]

i dunno what it puts out, but if urs is bad, i would suggest getting an MSD blaster 2 coil. easy intall, and its only about 30 bux. not bad for a little gain.

[forrest89sei]

Try This:

http://img181.imageshack.us/img181/4772/page730largenp8.jpg

[lostforawhile]

Anyone know what there coil is putting out voltage wise.Out of the blue wire that feeds down too the fuel pump relay.Also, if possible check it while running. Mine is 11.5 volts. Seems a little low.the wire that goes to the fuel pump relay is ground,same wire that feeds the tach. the relay counts ignition pulses to tell if the engine is running or not.

[steveko]

I've tested the coil as described above was within spec.What about the voltage at the fuel pump itself?

Also,should it not be battery voltage at the relay and also the control unit.

[lostforawhile]

I've tested the coil as described above was within spec.What about the voltage at the fuel pump itself?

Also,should it not be battery voltage at the relay and also the control unit.the relay for the fuel pump will have voltage with the ignition on,a ground wire,and a wire from the ground side of the coil{the blue wire},and a power output wire to the pump. if you have the ignition on,and jumper the pump wire with the ignition wire,you should be able to measure voltage at the pump. your voltage readings with the car off sound normal. you get some voltage loss in the wiring.

[steveko]

I understand there will be some loss due to resistance but I'm looking for some real world results or readings with car running. That test was done with the car running at idle.

[Dr_Snooz]

Out of curiosity, what are you trying to diagnose?

[steveko]

Trying too find out if the tach signal voltage is correct.

[lostforawhile]

Trying too find out if the tach signal voltage is correct.i explained this a few posts ago,it's not a voltage. the coil has constant ignition power,it's the ground thats interupted. the tach counts the ground pulses.

[steveko]

Then why does the Honda manual tell you too check voltage at the control unit. Although it should be with the car igniton on not running.

[2oodoor]

HRMM, you should have been getting more than 11.? volts when the engine was running, huh.
You lose a lot of + voltage on the ground side too, If you have poor grounds at the battery to the block and to the body you will read low voltage. Also you can get misreads from poor leads on your DVM (meter)
You are not going to get battery voltage on the tach, it reads from the pulses out of the coil. You can probably "rent" either a automotive test meter which has a tach function, or a timing light with a bulit in tach, or just buy a tach from the parts store and just return it... that is how their tool "rental" works anyhow.

[lostforawhile]

Then why does the Honda manual tell you too check voltage at the control unit. Although it should be with the car igniton on not running.what control unit are you talking about? the ignition one in the distributor?. it will have voltage with the ignition on, and one connection goes to the coil,this is the coils ground wire. a coil works by a collapsing magnetic field. power is applied to the primary winding,then the ground is interupted,this causes the magnetic field in the primary to collapse inducing a high voltage in the secondary circuit. your tach and the fuel pump control relay count ground pulses at the ground side of the coil.

[steveko]

The control unit under the drivers seat.Check it out tach signal can be read check it with you're voltmeter then get back too me.

[lostforawhile]

The control unit under the drivers seat.Check it out tach signal can be read check it with you're voltmeter then get back too me.
what exactly are you trying to check? if you want to check for a tach signal, you need a seperate tach or a meter that can read rpm. the tach wire comes off the ground side of the coil. it's just a ground signal. if you measured between it and 12 volt hot wire,it would just be a square wave 12 volts dc. and the control unit under the drivers seat controls the carb and the valves in the black box.

[steveko]

I checked the coil voltage neg side isn't really neg all the time until the ignitor opens up the circuit. I tested it running puts out 11.5 volts. Thats with the meters red probe on the coils neg terminal and the black probe on the batteries neg terminal. I thought I made it clear what I was testing the tach signal voltage at the control unit under the seat with the key in the on position not running it reads 10.56volts. The manual says you should get battery voltage.

[lostforawhile]

I checked the coil voltage neg side isn't really neg all the time until the ignitor opens up the circuit. I tested it running puts out 11.5 volts. Thats with the meters red probe on the coils neg terminal and the black probe on the batteries neg terminal. I thought I made it clear what I was testing the tach signal voltage at the control unit under the seat with the key in the on position not running it reads 10.56volts. The manual says you should get battery voltage.
i'm not going to even try to explain this to you.anymore,we all know the book knows more then al of us and it circumvents the basic electrical laws. the ignitor opens the negative terminal on the coil,this is what causes the magnetic collapse in the coil that fires the spark plug. it's a switched ground it's not a positive voltage. if you are reading voltage between the negative and the battery terminal negative,you've eithier got your meter on the wrong terminal or you've got a problem.

[steveko]

I gotta go test this thing again.

[steveko]

I don't need it explained I understand that it is a ground. And the voltage reading at the control unit at term 11 is probably a feed coming from the fuel pump relay through the blue wire too the control unit.As far as the coil goes Here's my readings with the car running meter is not calibrated correctly so reading may vary from others.
Look at post 3 for how too test.
Readings Taken at coil
Ok Terminal A=13.71
B=0
C=13.71
D=13.20or there about.

[2oodoor]

your diagnostic techniques have taken on a life of their own, it is fun to sit back and watch

It is not a negative circuit in terms of polarity, it is a negative circuit in terms of algorithms. It is a form of stored energy from the primary ignition. If you think it is negative polarity try hooking a wire from the coil (-) side to battery ground for a while and see what happens.
You need a graphing multimeter or ociliscope to see and measure that signal properly, if we are speaking strictly on technical terms.

All quandry aside, you are going a way round about way to your goal of testing the tach and fuel delivery issues. You should get it resolved before long, there are plenty of experienced head scratchers around here if you keep posting progress.

[2oodoor]

a quick search turned this thread up, maybe it will be helpful even though you are not working on a no start at all problem.
http://www.3geez.com/forum/showthread.php?t=49235&highlight=coil+fuel+pump

[lostforawhile]

what i was trying to explain is the coil has a hot that is always on with the key at ignition. the igniter unit in the distributor interupts the coil when it calls for a spark. the interupting of power at the primary winding of the coil causes the magnetic field in the primary to collapse this induces a high voltage in the secondary windings which goes to the spark plug. a coil only has two terminals. a hot wire and a ground. the tach and the fuel pump relay count pulses of the ground terminal. if you read any voltage at the ground it's probably feedback induced into from the secondary.

[steveko]

Thanks for the info guys I guess I got off track there which is easy too do when you're reading so many opinons. I do understand exactly what you're saying lostforawhile completely. Thanks for you're help.Also thanks for that post find roodoo2. Just wondering when that guy jumped the terminals 1&2 together on the fuel pump relay did he turn the key on or not too see if the pump ran?

[steveko]

I was just looking at the book and there is some discrepencies between what you are saying and the book. 1st Testing the relay blue wire too ground said too have battery voltage with the key on I have confirmed this by testing mine.Also,At that dammed control unit it said that between terminal 32ground and 11coil signal there is battery voltage mine read 10.56v with the key on.

[2oodoor]

if you read the thread I linked, Lostforawhile said way back that that must have been a misprint, thus it has caused confusion many times for others. I agree with him that it is misinformation right out of the factory manual.

[steveko]

Well that sucks because I am actually getting a voltage reading at thoughs test points. What part is misprinted an furthermore why am I reading voltage at these points.

[lostforawhile]

what might be happening is you are getting a voltage reading,because the meter is completing the circuit between the ground and another ground, just a ground loop is all. if you disconnected the ground from the coil and connected the meter between it and ground,the current will try and flow through the meter. and you'll register some voltage, it is the ground terminal of the coil though. normally that ground is switched by the module, if the module has the circuit open, the current will try and find it's way to ground through your meter.

[steveko]

Aha thats what I thought was happening. Thanks for you're assessment.