Engine flooding with fuel. DJ2.1 1989 Auto. Broken down in roadside

[maxstu]

Righto! Your help required here please! Have changed FPR (same issue) and extensively tested the injection ECU unit once again. The only (important l know) is no OHMS reading to all four injectors. I should see a reading of approx 16-16.4 ohms. And Im getting nothing!
So what is going on? Also test number 21 and 7 l dont understand. What is the procedure please?
Waiting for your replies with thanks.
Stuart

[maxstu]

Meanwhile, a very unproductive afternoon.
l went through all the earth wires in engine bay associated with the ECU and replaced a few scabby ones.
I then watched a youtube video how to correctly test a four post relay. I tested both relays and they both seem fine. Here are the results. If l have incorrectly tested these relays, shove up an answer on here showing me the correct method.

[Stesaw]

Lets hope it's nothing ECU related!

[maxstu]

So, l'm at an impasse. I need to find out why the pump doesnt prime but continuously runs. And why all four injections show no OHMS readings.
Looks likes a trip over the pond to The Samba club....or dare l say it? Club 8090 fartbook!!!

[maxstu]

Lets hope it's nothing ECU related!

Wash your mouth out!

Im not certain of my next move TBH.

[maxstu]

Lets hope it's nothing ECU related!

Wash your mouth out!

Im not certain of my next move TBH.

Beer! And plenty of it.

[Stesaw]

Maybe flyleads to the ECU and then to related bits that the loom would connect to, test if its the loom or something else.

[Mocki]

Your relays are electromagnetic switches , so if it clicks and the two contacts are joined they are working correctly 
that is basic, 
pos to 85 , neg to 86 , coil causes the contact 30 and 87 to be joined , it’s either clicking and connecting 30 and 87  or it’s clicking and they are not being joined , or it’s just not clicking . 

low voltage or poor earth will show as not clicking or vibrating as it try’s but fails .


 

[maxstu]

Thanks to both.
As l have tested both relays with almost identical results then l will assume they are working. Will source another as a spare.
Im going to strip back ECU wiring loom to get to the bottom of no OHMS reading for all injectors.
As the injectors batch fire it got to be something to do with lack of ECU signal interrupting injector current. Hence flooding by constantly firing fuel into cylinders.
Or am l looking at the wrong end. Does the ignition switch current 50 play any part? It keeps cropping up in searches for DIGIJET issues.
Yet l would surely still have OHMS at injectors?
Yours, effectively chasing my tail,
Stuart

[R0B]

I have a spare auto ECU here you could borrow if it's any help.

[maxstu]

Cheers Rob,
Will PM you if needed.
Once l remedy no injector OHMS readings in ECU loom then l should be able to know if swapping out the ECU is necessary.
I may need a loom from someone though.
BTW is the ECU different for Auto and manual?

[R0B]

Yes it is mate.

[maxstu]

Yes it is mate.

Thanks and well spotted.

[colinthefox]

Righto! Your help required here please! Have changed FPR (same issue) and extensively tested the injection ECU unit once again. The only (important l know) is no OHMS reading to all four injectors. I should see a reading of approx 16-16.4 ohms. And Im getting nothing!
So what is going on? Also test number 21 and 7 l dont understand. What is the procedure please?
Waiting for your replies with thanks.
Stuart

First of all, my apologies for butting in here, as I have no specific knowledge of this particular fuel injection system, and it's ages since I did any petrol at all. But I used to have fuel injected Vol-vos in the 80s-90s, and they all seemed to suffer from the same problem, which was fuel hosing when starting. That seems to be what you have got.
In answer to your question as to what's going on with the test on terminals 21 and 7............

When cranking, the voltage from the starter is shown to the ECU at terminal 21 for starting enrichment. There has to be something that time limits this feature or the injectors will hose fuel continuously while cranking. On my old Vol-vos this was done by a nasty little bimetal switch which interrupted the fuel enrichment feed after a short time according to engine temperature, and which failed closed for a passtime. These switches were not shown on the fuel injection diagrams as they weren't considered part of the injection system. Once this switch was disconnected the engine had no starting enrichment so would start normally when warm, and sometimes when cold.

So............

If you were to disconnect the wire to terminal 21 where it connects to the starter motor (or wherever it is connected), this might stop the fuel hosing. Then you would be on the way to finding the root cause. Then you would have to look for whatever mechanism this system uses to time limit the starting enrichment. (bimetal switch/ temperature sender etc) As I said, I have no knowledge of this particular system, and I understand that others trying to help you do!
 

[maxstu]

Over the phone a fantastic Auto electrician based in Kent has narrowed it down to either ECU earth fault or faulty ECU internals. As all tests show external grounds are good its to another ECU for tests.
PM'ing you Rob.