The engine turns over on starter fluid but won't fire from the fuel system. Pump is operating. Where is the ground for the ECU in the trunk? Thanks everyone

 

From the words used I think?? you be in the USA, might pay to add that snippet to your profile. Markets do vary on many things.

I would be looking at Injector Pulse has gone AWOL. VERY common on the D Jetronic system.

There is a trigger board inside the distributor, just under the rotor. There is a magnet in the heel of that rotor.

As the magnet passes over each end of that board, the imbedded switched trigger the ECU to fir the Injectors.

There a 2 different boards:

3 wire as made in the UK. Has reed switches imbedded, not reliable in any spoken language.
4 wire has Hall Effect sensors. Most reliable of all, and one of mine is at 800k Kms and still just fine.

So, count the wires exiting the distributor at the back, just under the cap, then the CORRECT sequence can be given to find the missing pulse.

Back later, other things need my attention.

 

MMMMMMM,

I note in your other thread that you have replaced the trigger board and rotor, goodo.

That would be a 4 wire board, tick.
Where is the 4th wire connected, please.

Check that rotor does have the magnet in the heel, some suppliers group the Carby and EFI rotor as the same part No.
The Carby NO GOT magnet.

 

Thank you Grant, this seems to be a 3 wire setup or if there is a 4th wire I can't find it. It's a US car.

 

Thank you.

Looks 3 wire to me also. Odd, as I thought stocks of them dried up many years ago, oh well, someone has them obviously.

Testing is simple.

Remove cap and rotor.

You will need a STRONG magnet on a stick, and a SILENT area to listen.

NO ign etc, just a raw car.

Wave the magnet over one end of the board, you should hear ""clicking". NOT the Injectors, you are listening for the reed switches, and they are NOT that noisy, hence the quiet I mentioned.
Now the other end.

If that is OK, check the strength of the rotor magnet. I use a 10mm socket. If fthat magnet lifts that, all is good.

All OK, refit the rotor and cap.

The fact it fires on Bang Spray, deletes spark as a cause.
Have a beer.

ECU test, simpler.
CAREFULLY pull back the rubber boot on the TPS. Unplug that flat loom plug, and replug it, and pull the boot back. Its just a check for contact. They will start and run with the TPS unplugged, its the acceleration thats a tad slooooow.

Ign ON, LISTEN, and open the throttle SLOWLY, and LISTEN, for the "clicks" of the Injectors as the internal wiper passes its segments, should be 9 from memory., and memory sucks, so just count them anyway.

That confirms the TPS is "talking" to the ECU, and the ECU is "talking" to the Amp on the radiator panel;, and the Amp is "talking" to the Injectors, whoopee.

If that OK, it should start and run, simple eh.

Come back if any of the above is amiss, and I will walk you through it. Its been 25 years, but the too many hours I spent on that system is still in the Grey matter, albeit faded somewhat.

 

Thank you again, I just realized I posted the wrong photo last time. This is the trigger board connection. I bought the board from a local brit car shop and it matches the old board.

 

Ok the trigger board does give off that faint 'plink' noise as you pass a magnet over the reed switches (ironically the old trigger board also tested good) and the rotor will pick a socket off the table. Opening the throttle does produce a loud click, think I counted 19 of them.

 

Well done.

So that means the D Jetronic is doing as asked.

You mentiond the pump is running, GOOD.

BUT, is it pumping Gasoline.

Your fuel filter is on the A Bank Inlet manifold front corner. Remove the hose, extend it over the guard, and CAREFULLY switch ON the Ign. WATCH OUT, as the pump SHOULD spray a shiiit load of fuel at decent pressure, so a helper holding that hose so it dont do the snake thing would be smart.

That bit tests OK, reattach the hose.

Being LHD, I will use the Crystal Ball I have, made in Mumbai, and assume the brake booster etc is on the LH side of the engine bay.

Below that, is the fuel return hose, attached to a steel pipe poking into the engine bay. Remove that hose, extend it outside the bay, and do the same. That hose should NOT do the snake thing, as the return is basically deemed zero pressure, but common sense states, maybe 4 or 5 to "push the fuel to the back of the car.

If you got flow there, the rail is being charged, and fuel will be sitting, under pressure at each Injector.

Reattach that hose.

Turn the Ign ON then OFF a few times, thus purging the rail, and then with the Ign ON, press the Gas pedal to the floor and back to idle position. This will squirt fuel into the cylinders, so go for start.

If that has the desired result,you need a beer.
If it starts and dies quickly, then I think????? the CTS (Coolant Temp Sensor) located on the backside of the B bank thermostat housing is having a bad day. Unplug it, bridge the termials in the plug, and try again. Lokk at the 2 wires in taht plug, they are reknown for sraying.

I am NOT sure, basically I forget, but that CTS is a Prime Signal to the ECU for Injection pulse. I DO know that the HE is a dead duck if the CTS and/or its wiring is damaged, but not 100% on the Pre HE beast.

On the LH side of the top radiator support panel is an alloy cylinder looking "thing", with wires and a Vac hose. This is a MAF Sensor. They are NLA many years now. The wires do fail, dead Injection system, and Vac leaks means super rich running, we not there yet.

 

The fuel return rail is flowing on the return side (also disconnected the trunk hose, blew the return out with lung power) but no fire. Also noticed the fuel pump relay took up smoking so there's work yet to do.

 

Fuel pump relay replaced, pump is talking. No fire. Thanks for all the help so far, hopefully the gremlins are thinning out.

 

Assuming the system completely depressurized when I checked the pressure & return sides, how long would it take for the pump to get everything back up to pressure at the regulators. I replaced the relay, let the pump run for about 10 seconds then cycled the ignition and opened the throttle wot before hitting the starter. No bangs yet

 

2 cycles of the pump circuit should be enough.

I am confused a tad,

It runs, sort of, with Ether, but not with Gasoline. My brain is saying no bang juice getting squirted. YES there is clickety clack, BUT that does not prove they are spraying liquid.

What pressure are the 2 FPR units set at, mine were 38psi each rail.

All 12 out, NAH, not possible as in Injector failure.

I would lift an Injector, then with PROPER PRECAUTIONS, Ign ON, Open the throttle (so you hear the clicks), and see what sprays.

I have to ask, coz I cannot smell it, how old is the fuel??

 

Tanks are new, fuel is fresh 93. I will do the ether test again to make sure I still have spark.

 

Ok the engine is catching on the fuel system without ether but it won't turn over and stay running. So close!

 

connection at the coolant temp sensor on the b bank looks good, feels tight. Bad cold start relay?

 

Bugga, that be a stubborn one there.

Next:

Voltmeter on the +ve side of the coil.
Go to Ign ON, should see about???? 7V.
Go to Crank, should see about??? 12V. That 12v is only applied at crank, to WHACK the coil hard to start the thing.
We call that system a "Ballast Ignition System" and the coil is a generic Resistor Spec coil, basically a 6v coil.

Grab any old spark plug, attach it to any lead, and lay it on the Dome head nuts. Crank it, and note the spark quality.

My thoughts for all that are"

MAYBE, the Ign Switch electrical section is playing up, MORE common now that beer in a bar.

Read the attached when you can.

Lets know what you find.

 

New observation - with the key on/ pump operating you can hear a faint gurgle/ hiss sound coming from somewhere along the rail (can't tell which bank). No leaks but what happened this morning led me back to fuel pressure. I replaced the cold start relay and let the pump run for a 5 count. Said a prayer, hit the key, heard it spin and catch several times in quick succession, then silence. Cycled the ignition and tried again for about 10 seconds but it kept spinning, never caught. Also the pump is not cycling off it just keeps running.

 

Mmmmm,

Gurgling/hissing on that system is kinda normal. Mechanical FPR,'s, one on each rail, will do that as they :"bloed off" and return fuel to the tank.

Pump running without the ECU Timer, Freddy been there, and Earthed the Orange wire on the Fuel Pump Relay, COMMON for trouble shoo0ting, BUT NOT for normal use. The ECU relies on an Ign Pulse to over ride the timer circuit, and keep the pump running, hence in a stall situation the pulse is lost so the ECU stops the pump, reduces fire risk, eh.

I still need to know the results of y previous ask.

It sounds seriously like its running on the Cold Start Injectors. They are FICKLE at best. They are meant to activate ONLY during the Crank cycle ONLY. I remove them on all my cars, as the problems are too stuoid for words in here. Block the suel rail sopigot, tuck the wires out of sight, leave the Injectors there to fill the Vac hole for now. MAke some oval plates later when the beast and you are happier.

BUT, where is the Injector Pulse, and/or spark when you go off Start Position???

Systematic system by system sorting is 100% needed, not flipping around all over the engine bay etc.

That 3CU ECU in the boot is Purely an Analgue Grand Daddy of what we have today. In all my years I have never seen one die. One was full of water, not a Jag, a long time ago, drained the water, left in the sun, an a few hours, and it worked just fine. Try that with todays rubbish, you only got to look wrongly at them, and they go legs up.

 

Results are in, getting 4- 8 volts with the key on and weird vacillating in numbers with the starter engaged. Coil is new, tested before it went in.

 

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