With ECU subtilites guessing is all I have got, David - but directly grounding a powered 12V source is ill advised; there are no fuses in the engine management system…
You are of course absolutely right in testing injector spray. But as the duration of the opening pulse is in the 50 millisecond; only an oscilloscope can verify if the duration is correct. And if it is not; the ‘why’ remains - I’m just suggesting something that ‘may’ clarify issues.
Frank
xj6 85 Sov Europe (UK/NZ)
The first question is, does it spray at all. This is important because it seems the engine doesn’t see nearly enough fuel, but something clicks.
Grounding something 12v from or to the ECU is not good, no…
Hello all,
not sure where I got this schematic but if it is not from this thread may be it could enlight the debate. My apologies if everybody has it already. I have also somewhere on a media to unearth a quite complete documentation about the whole Lucas / Bosch injection and ECU let me know if it could be of any use to post it there
Ended up in hospital last week. Cellulitis. In for 4 days so they could use IV antibiotics. Leg was kinda messed up, looks better now. I’ll see if I can get a couple of things checked out this weekend.
Ow I feel your pain, I had ‘that’ a few years ago but it wasn’t responding to the drugs, 4-5 months in it turned out I had Micro Bacterium Marinum picked up in Fiji when I was swimming.
Greetings from the front. Legs still swollen but was able to do a little. Took off two injectors to see if they squirted a little something. NOTHING. Put a paper towel in jar I was hoping to collect gas in and absolutely nothing.
So the injectors are not injecting. From what I hear, a problem.
So I’d like to concentrate on electrical problems and get the injectors to click loudly.
I’m 99% sure that’s the problem. There might be other problems but nothing to keep car from firing at all. With starting fluid it starts right up first time every time so ignition is adequate.
Injectors click ever so slightly so everything is connected to something. Bad connections very possible.
What about resistor pack on fender by air cleaner. Can that be checked with VOM?
I thought someone said it reduced voltage slightly. 12v in 9out?
My legs are still sore so it limits time I can stand there. But I can do a little something and take a break. One good thing about this problem is all the work can be done while standing at fender. No crawling under car and being a contortionist and spending an hr to get 1 bolt off.
The resistor pack is just a pcb with many smd resistors. Should be straight forward to test.
The other side is ground to ECU to coil and ECU ground to injectors…
Tom it sounds like you need to remove all the injectors and either have them professionally cleaned or look at some YT videos about how to do them at home.
Sure is, Tom - and I assume the negative result was while cranking, and with the fuel pump vrified running…?
Now disconnect the connector on one removed injector and apply voltage directly to the injector if it still does not spray, the problem either a clogged injector, as Robin implies - or no fuel pressure delivered to the injector…
As an aside; the injector resistor pack has 6 resistors, as David says - each injector connected in series with an injector. The resistance over each resistor is in the 6 ohm range (or thereabouts) - and is there to protect the ECU if an injector shorts internally. It also means that when current flows there is a voltage drop over the resistor, and a further drop due to the resistance in the injector coil - the total current is limited by the sum of the resistances. Ie, the injector voltage is in proportion to the resistor in the pack and the 2,4 ohms over the injector. So the injector works at some 3 - 4V and around 1,5A…
Frank
xj6 85 Sov Europe (UK/NZ)
It’s several but that of course makes no difference. I thought we had checked the injectors before - a 9V battery is a bit much but will work. Brief taps only.
Not to the extent of actually observing the injectors spray, David…?
It’s vitally important that the pump is running during spray testing. The easiest, in this case, is either to remove the air filter and prop open the AFM flap - or remove the fuel relay and jumpwire between white and white/green on the relay socket. Either will run the pump with ignition ‘on’ without cranking the engine - making it easier to use a separate battery to trigger the injector…
Frank
xj6 85 Sov Europe (UK/NZ)
Ok been away awhile. Have a 95yr old house and three old cars and it’s getting the best of me.
Have a little new, good news.
I did manage to check injectors using 9v battery to hot wire injectors. Squirted just fine. So I think everything works fine except the triggering of injectors, which is where we were before but now we KNOW injectors shoot gas if triggered.
A question. Does fuel pump run with ignition at 1st or second position? Or not until you get to crank position?
So it boils down to triggering. I would so much like to hear at least a sputter, cough, backfire or something.
It still starts first time every time with ether.
Second position, first position should only run accessories.
To clarify, the pump won’t run at all by simply turning the key ‘on’.
It will run with 1) the key turn to ‘start’ and it will run if 2) the flap in the air flow meter is opened.
In the first case put the gearshift in “D” and turn the key to ‘start’. You should hear the pump run.
In the second case remove the air cleaner housing to expose the front of the Air Flow meter. Turn the key ‘on’ (#2) and then use your finger to push open the flap at the front of the Air Flow Meter. You should hear the pump run
Cheers
DD
**
What is odd is that you can hear the injectors clicking while cranking, Tom - with no engine ‘sputter, cough or something’…
What you need to do is to remove an injector and observe the spray pattern while cranking, triggered by the ECU - compared to the spray when voltage is applied directly.
When it starts with start gas, one would expect engine to run on if the injectors are operating - once the engine catches; the first hurdle is passed. Two possibilities; the injectors are not properly operated by the ECU - either because ECU is not getting the proper signals from sensors, or doesn’t respond properly to the signals…
…or the engine ‘cold start’ set/up/idle set-up is not conducive to starting - if the engine cannot idle cold, it cannot run. The start gas bypasses normal injection and the usual cold start devises - but the engine needs sustenance for running on. Doug repeated a vital element; the reed switch in the AFM - which triggers the fuel relay in ‘run’ when the engine is drawing air and the key is released from ‘crank’.
If not working as Doug described, only a small deflection of the flap should start the fuel pump; the pump will stop as key is released. Normally, enough fuel pressure remains in the fuel rail to briefly run the engine. But if the non-return valve has failed, or there is a sizable rail leak-down, fuel pressure will instantly drop to zero - and the engine won’t run…
Given that the engine started and ran OK earlier (?), and you did not interfere with the AAV or idle setting - these cannot be the cause?
Frank
xj6 85 Sov Europe (UK/NZ)
The injectors do nothing when cranking.
Remember the noid light will flash when cranking. But it’s very dim and it’s just a little stinking bulb.
I’ll have to recheck fuel pump operation as that’s vital obviously.
Then check wires for bad connections. Wires to/back from ecm? Maybe it’s just not enough power as you mentioned before.
Coil looks ancient could that be throwing things off?
Coils are cheap. Could throw one in.
slim chance that the coil produces a weak spark. And the ether is more flamable than gas… it fires.
Try Frank’s age old spark test. Remove a plug or use a spare. Gap to .075 or so. now crank and observe the spark. Hot blue is needed., wimpy yellow will not do.
Frank’s classic test.
Carl
No I meant would a bad coil make the triggering of the injectors be weak. That wire with bullitt connector comes from coil to ecm.
???
No. The coil post serves as a connection from the distributor to the ECM.
