Urgent Injector Pulse how to test

[asbestos]

Hi all,
i have changed my injectors as part of a forged rebuild new 850 side feeds with duel feed rail, but having trouble starting, timing ect all ok, is there an easy way to test if the injector is pulsing, i have a feed 12v one side but nothing on the other side when engine cranks, or do i need a resistor type tester, or is there another way to test, car will just fire up for a few seconds if a little fuel sprayed into intake,
Ford Anglias were never this hard to work on,

[Peter Gidden]

Easiest tool for you to get hold of is a noid light. Try a good local tool shop.

A multimeter or light bulb will not pick up the pulses, so unless you have a suitable tool no pulses will be apparent.

You could always make your own noid light:

http://www.noidlight.com/

[Mike N]

Ford Anglias were never this hard to work on,

They weren't as fast though!

[asbestos]

Once again Pete, many thanks,
made up an LED and their pulsing scratching head time and sleep on it till in the morning.

[Peter Gidden]

Once again Pete, many thanks,
made up an LED and their pulsing scratching head time and sleep on it till in the morning.

Well done!

OK, 5 basic requirements to get an engine running...

1) Air
2) Fuel
3) Compression
4) Spark
5) Timing - Spark and Valves

So ignore 1
2) is fuel pump running when cranking? If in doubt, bridge B+ and FP.
3) new engine, so let's ignore for time being
4) are you getting good spark at plugs?
5) cambelt timing correct? ignition timing about right?

[asbestos]

Hi Peter, i have checked everything, all ok, except she only fires when i put fuel into intake manifold and runs for a few seconds, fuel pressure there, (sard FPR reg with guage) process of ilimination leads me to think its the injectors as there is fuel in the twin feed rail as well with pressure, what would stop new injectors from working correctly, when i fitted injectors sard denso again, i copied wiring as per the original as the connectors were slightly different, is it possible the + & - are opposite on these new ones. ?

[Peter Gidden]

No polarity on injectors.

OK, so couple of questions...

Are the injectors high or low impedance? (To check, unplug them and measure resistance of them with multimeter.) Expect a result beteen 4is ohms and 2ish ohms.

Which ECU you using?

Still using the ballst resistor pack on rear firewall?

[asbestos]

Hi Peter, sorry for the delay trying to run a large buissiness time is never your own even at weekends, this project was to take my mind off work, but im learning a lot & still enjoying it, I checked the new 800 injectors they are 14 ohms
the old 540 injectors are 3.5 ohms,
ecu is original rev 3, i do have a new APFC waiting to plug in but i wanted to make sure everything was running ok before pluging it in,
every thing else electrical all as original rev 3 ballast pack
resistor ect.
Thanks again
Carl

[Peter Gidden]

I checked the new 800 injectors they are 14 ohms

the old 540 injectors are 3.5 ohms,

every thing else electrical all as original rev 3 ballast pack
resistor ect.

You're trying to use high impedence injectors in a low impedence circuit. There's your problem.

[asbestos]

Is there a way round it without buying new ones,

[Chris]

I would imagine you need to remove the injector resister packs and re wire as required.

[Peter Gidden]

I would imagine you need to remove the injector resister packs and re wire as required.

Correct. Unplug resistor pack. Cut the 5 pin plug off. Strip all 5 wires (12V in and 4 x 12V out), twist together, and solder. Wrap with tape and plug back into loom.

If you ever want to reverse, just get another resistor pack from the classifieds.

[asbestos]

Thanks for all the help Peter, really appreciated.