1800E No Fuel at Injectors
 

Hi everyone

I am at a decision point in the investigation of a current fuel injection issue on my 1800E. The fault is that I have no fuel at any of the 4 injectors (or the Cold Start Valve although I suspect that’s a different issue). The fuel pump is operating and I have 30PSI fuel pressure in the gallery. The voltages, resistance and continuity of the loom is as expected. Pins 16 and 24 have 12.5V at the ECU connector. My next move, I think, is to have the ECU checked out as I believe the power to pin 24 may have gone adrift within the ECU somewhere?
Ideally, I would slave in a known ‘good’ ECU before spending a lot of money having my ECU tested and repaired. These are obviously no longer items that are plentiful or cheap. Dare I ask if there is a Member out there that might have a ‘loaner’ Bosch ECU 0 280 000 017 that I might borrow to confirm my fears?? or does anyone have any other avenues to look at before I commit. Prior to this incident the car was running well. I did fit a 123 Ignition in July but it was running well up until now. The only thing I may have shot myself in the foot with is temporarily replacing the Main Fuel Relay with a non diode relay – could I possibly have damaged the ECU without the protection of the diode? I have since replaced this relay with a diode relay.

Any help would be very much appreciated.

Trevor;

You have not given preconditions...was car running before this? ...or is this an attempt to start after car has been sitting 15 years?

...but the statement: "I have no fuel at any of the 4 injectors... fuel pump is operating and I have 30PSI fuel pressure in the gallery." ...is unclear!...no...worse than unclear!...it is contradictory! By definition, when Fuel Rail is charged, you have fuel at Injectors!

I don't agree with your theory of "24 [ECU main power in] may have gone adrift within the ECU somewhere"...because if there was no main power in the ECU, the FuPu control circuit would not/could not be functioning to energize FuPu.

If the Fuel Rail is charged as you are reporting, then it is up to the ECU to energize Injectors as a function of Triggers coming from Distributor contacts...you can check Injector function as described in Chris M's test here: http://www.sw-em.com/bosch_d-jetroni...Fuel_Injectors ...but before disassembling things, you could just quickly test for Injector function by listening for enrichment clicks (Ign ON, then opening Throttle slowly).

See also: http://www.sw-em.com/bosch_d-jetroni..._Documentation

Good Hunting!

“Prior to this incident the car was running well. I did fit a 123 Ignition in July but it was running well up until now.”

So, reading between the lines in your post I take it that you have fuel 'at the injectors', it is just that the injectors are not firing?

I assume that the fuel pump is running through its prime cycle to pressurize the fuel rail which indicates that the basic functions of the D jet controller are alive. For your particular problem, Ron's included description of the 'Chris Mullet' test basically sets out the process to follow.

However, before removing the injectors and spinning the distributor as described, I would first do the more simple 'enrichment test'. You need to do this test in a quiet area because you are listening for the click of the injectors opening and closing. With everything in place
1) turn the ignition to run (engine obviously not running)
2) allow the fuel pump prime cycle to complete
3) manually operate the throttle switch from full closed to full open and back
As you open the throttle to full open you should hear 11 or 12 clicks (can't remember the exact number) and no clicks as you close it. This test does require that the throttle switch is functioning.

If you hear the clicks then the injector driver circuits in the controller are functioning and at that point you could move to the Chris Mullet test and spin the distributor. Typically, rather than spin the distributor I would first suggest examine the wiring to the D jet contact switches in the base of the distributor to look for damage and check the operation of the switches as described in the Fuel Injection Fault Tracing Manual (page 2-21).

https://volvo1800pictures.com/docume...lt_tracing.pdf

However, since you have fitted a 123 distributor you can't do that although you can examine the wiring to make sure that you have not had a failure there. At this point you could proceed to the Chris Mullet test. If you fail the Chris Mullet test then you have a problem with the 12 distributor, the wiring to the controller or a problem with the speed sensing / trigger circuit in the controller. The latter is not impossible; but, unusual as the controller is probably the most reliable component on the D jet system. If you still have your original D jet distributor I would be inclined to re fit it to see if this resolves things. Unless you have some electronics skills testing to determine if the outputs of the 123 distributor have failed will be somewhat complicated.

I am suspect about the 123 distributor mainly because it was a recent fitting. I am not implying that the 123 distributor is a poor design; but, it is all electronic. Electronic failures tend to have a bath tub like failure curve. They may have a higher infant mortality and if they make it past that stage then they are usually good for the long-run until old age gets them. Your 123 distributor might have had an infant mortality problem.

The non functioning cold start valve may or may not be relevant. You did not specify the year of the car and that is important since the cold start mechanism changed significantly around 1972 or 1973. On the later cars the cold start was pretty much independent of the controller and should function during cranking - as long as the valve itself hasn't failed which is not uncommon. On the earlier cars the cold start is controlled by the controller and that might be a relevant symptom.

The purpose of the diode in the main relay is to block the relay from energizing in the event that somebody connects the battery in with the polarities reversed or tries to jump start the car with the jumper cables reversed. Reversed polarity would damage the controller so the relay is prevented from operating. If you did not reverse the battery polarity with the diode less relay there should not be an issue. When I was younger and did not have the $ to cover a genuine failed main relay in my 142E I used a $ 3 automotive cube relay as a replacement without issue.

Guys

Thanks for your swift and comprehensive responses and apologies for not making myself clear and not giving you all the relevant information. I am at least a bit more confident, having seen your replies, that I haven’t trashed the ECU!
For clarity, the fault is that the Injectors are not firing, as you correctly pointed out I do have fuel pressure in the gallery and therefore at the Injectors. The Fuel pump does run through its priming cycle.

I have done the ‘enrichment check’ and I can hear the clicks confirming the Driver circuits are working. This has removed my concerns about the power at pin 24 I mentioned.

I think my next step will be to refit the original Distributor and see if the triggering contacts do their job and I can at least get the engine running. I shall be disappointed if the 123 Ignition has failed already. I’ll do a good wiring check too while I’m in the area.
As for the Cold Start system - My ‘E’ is a 1971 model and has the Cold Start Relay rather than the later Thermo Time Switch. I am getting power at the Valve connector so am suspecting the Valve has failed.

Many thanks again guys and I'll let you know how I get on.

If you refit the original distributor for test, make sure the trigger contacts are functional first.

Check the D jet harness wiring carefully where it exits the harness and terminates at the plugs. Doing this for all the plugs is a good idea. The insulation deteriorates due to heat exposure at the plugs ends first because that it is where the actual wires are directly exposed. The insulation may look OK; but, when disturbed it can crumble and fall off leading to erratic behaviour. You may have damaged the trigger wires by flexing the harness during the 123 install.

My 142 E is also a 1971 model so I know the D jet harness wire problem. The injector plugs and head temperature sensor are usually the early failure locations followed by the throttle switch and the distributor. On the harness leading to the injectors I had to cut back a good 30 cm into the harness where it runs along the fuel rail (right back to the firewall) because of crumbling insulation. Even though covered by the plastic sheath, it gets cooked from being directly over the exhaust manifold.

All noted thanks

I'll have a good look over all the wiring and particularly the insulation and prep myself for some repair work!

Does your 123 you have the F.I, triggers the same as the original one?

Hi Derek

The 123 does still signal the ECU via pins 21 and 22 but not by way of Triggering Points, it’s all electronic. Is that what you were asking? The wires from the 123 push into the female connectors in the original Triggering points connector on the loom.

Yes, I guess that is what I'm asking!. Basic question. Since fitting the 123 has the car run normally? i.e. Running and driving? If yes, at what point did it fail to run? Was it just that one morning it failed to start or did it fail when driving?
If it just failed, what had you done to the car in the period before the failure. Sometimes just doing small jobs under the bonnet can pop a wire off or something small like that.