V8 fuel injectors.

So today has been eventfull.

I can confirm the the fuel rail is drawing fuel into it via the supply line. There is vacuum at the cold start injector supply and at the fuel return hose. If I clamp the supply line off, it eventually stalls.

I followed the AVO tests in the manual and other than a small anomaly in injector 2 circuit, everything is 100%. I cleaned the contacts/pins on the power resistor and that fixed the anomaly.

A mate of mine pulled the ECU apart and inspected/tested everything to have it come back as good. Very clean inside, no dry soldiers.

I eventually decided that I would pull the plenum apart and pull the injectors. It's probably going to happen anyway.

When apart we tested the injectors during cranking. Both banks fired as they should. But it was a stream. Next we pressurised the rail and cranked with no pump. Initially it streamed (40PSi) then eventually went to a spray at around 25PSi. But the injectors did not leak when not activated and at 60PSi. The system held its pressure.

So currently I have two trains of thought.
1-the ECU is holding the injectors open for the full duration and vacuum has the chance to draw in fuel to the cylinder's unmetered, causing it to run, albeit rich. Thus when fuel pump is supplying, it floods out.

2- injectors are so worn they are allowing the fuel to pass at a large quantity even though the duration is short.

My mate is rigging something the open an injector while we pressurised it and see what the pattern is like. If it streams, I think the injectors are shot. If it sprays, then there is another bunch of voodoo going on.

I have fully discounted the ECU yet, but it is unlikely.

Tomorrow I will pull the left rocker cover and redo a static timing and basic tune, to get back to square one.

I am hoping the gremlin stiffs up and jumps at me!

100% sure fuel pressure reg is ok?

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Originally Posted by Rick1970

100% sure fuel pressure reg is ok?

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Yeah, it's new and adjustable. So even if the gauge was incorrect I can still wind it up tighter than spec. When I measured vacuum at the return, I had it completely unwound.

We used 3v to operate the injector and as the pressure increased, it had more of a spray pattern. Even actuated it via the loom to get 3.8v and same deal.

I am at a point now where the ECU is holding the injector open too long, allowing vacuum to pull the fuel through or the coolant sensor which tests fine actually isn't and is telling the ECU to let more fuel in or the injectors are buggered on some level.

I am hoping to find a resistor to bridge the coolant sensor terminals and take that off the list first.

I will make a decision as to where I head next.

Can you test the coolant sensor resistance at the ecu plug, maybe a break in the wiring somewhere. Had to replace the sensor plug on my old pig as it was crook.

Checked and i do have an ECU and injector resister block here, had both connected and running on my old rangie when fault finding, so should be ok. If you want them, pm me an address and i will post them to you.

Yeah you can. When tested it was within the spec listed and only slightly higher than at the sensor itself. But it's one of those things I'm not 100% with and you can't voltage drop test it.

Rick, Il PM you regarding those parts would be much appreciated and I am sure the LR karma will be spread on.

Il keep up the testing until it's going great again

*Update*

Unfortunately even with some donated parts thanks to Rick, getting this old girl started is still being very elusive.

So, to start at the begining, it(89 RRC 3.5lt Flapper) was running without the fuel pump connected, albeit very rough. As soon as you connect the pump, it over fuels then stalls.

Ran every electrical test in the Rave manual and in the Lucas L electronic Flapper manual as found on here. Everything has come back in spec.

Dismantled the plenum and checked the injector spray, it looked poor, but from research looked pretty standard. I did order new injectors though unfortunately they didnt come in time before i reassembled. Replaced Coolant sensor with the OEM Lucas type, even though the previous one tested fine. Replaced a bunch of vacuum lines that looked suss and adjusted the rising rate fuel regulator to 40Psi.

Started without the pump connected again and corrected timing/idle. Connected pump, stalled. Fit given resistor pack, same deal. Fit given ECU, would not start. After I was doing some more checks with the power on, it decided to start. WOOHOO!!!

Nope, that was a celebration made WAY too soon!

It would idle fine, but when revved, there was a massive miss unless you opened the throttle up progressively. I seemed to get over most of this by winding up the fuel pressure to 65Psi. Again it idled well, not a huge miss when revved, so I decided to go for a drive.

The drive started ok, but as it went on, the miss got worse. Upon returning home I parked up the driveway which isnt steep and it struggled to get up without stalling. So that night I ordered all new leads, Plugs, coil, cap and rotor, thinking there must be a broken link somewhere.

Well, it wont start now. Not on that ECU.

Swapped ECU over and it will start without the pump, then die with it.

So I static timed it again, made sure everything is as it should be and still no go.

This morning I popped the cap off the AFM after a bit of research last night, with the hope I would find the biggest mob of salt water corrosion ever seen on planet earth. Unfortunately it was perfect! I did have the intention of adjusting the flap spring to see if that was why it was flooding. Before attempting this I had a bit of a play.. I got it started on the old ECU and with it running, forced the flap closed. Amazingly enough it started to rev more freely and smoothed right out. I thought id do this again, blocking the fuel pump contact and hooking up the pump again, I got it running really smooth then removed the contact block. It ran ok for a couple of seconds then it slowly died. Swapping ECUs and setting the flap in several positions, still didnt start. I am holding off on the adjustment until i can get it running properly.

I managed to find the schematic for the ECU and this afternoon spent a fair bit of time testing bits and bobs to try and get a better idea why.

From what I know with the new ECU, the injectors arent firing. And it seems that the Transistors for injection are not getting triggered. There is a signal at the pin and constantly shows 12.5v. With the old ECU, you can see the transistors being triggered, but when ohming them they messure three times more than those in the new ECU.

Other things I have done are bypass the overrun relay/switch, removed the Ballast Resistor at the coil and in the past completed the Bosch bin024 module replacement.

There is probably more that I have done, but cant remember right now.

Currently I am thinking about removing the plenum again to fit the new injectors.

If anyone has any other ideas, remedies- I will be very much open to hearing them. With an impending move back to Adelaide mid November, I really need this car going.

Thanks

I know that it may be far fetched but I have done it on a Federal injection system that I fitted to a 77RRC.

You don't have the flapper on backwards by any chance.?

Regards Philip a.

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Originally Posted by PhilipA

You don't have the flapper on backwards by any chance.?

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Ha, this is funny. Sorry..

Fortunately for me, it's actually one of the few parts that have not been removed from the car.

Thanks though.

Youve done a lot of testing but cant establish if you have meticulously checked the wiring under load.
This sounds more like a wiring issue - somewhere in the loom between the inputs and outputs is a high resistance point - or I have seen weak earth under load give fluctuating voltage at any point in the system EG fuel pump or ECU or any input output device.
BTW You cannot just check resistance on a wire to establish integrity I.E. Ohms test - the wire must be under load and voltage drops along the path are tested.
It seems illogical that the injectors are at fault or any of the other devices - as it has been yr daily driver.
My suggestion is to inspect every wire in the engine management loop for a rub or break - is any part of the loom rubbing, have scotch locks have been used anywhere, check all pins and terminals to pins for multiple copper strands adrift etc. Be extremely thorough.
Now power up - check battery voltage at the input side of every feed point to Input and output devices. E.G batt voltage at ECU or fuel pump input. A voltage drop of 0.1 V between battery and device is a suspect wire.
Check output voltage from ECU to actuaors or any output from ECU. E.G at flapper or any other device that receives a feed from the ECU. Be thorough.
Now check again as best you can after start - is the voltage at the pump or ECU stable over time?

We all tend to assume its an input or output device first but it is wiring issues that cause most faults - like the body if you have have healthy organs but a restricted vascular system then the system functions poorly.

If its a perfect body and you want to keep it then an aftermarket ECU with wideband would be a good investment - see FAST EZY systems in the USA - however AUD is tanking right now.
Best of luck - I feel your pain.

Replaced the EFI relays? I found a dodgy one on a later RRC system not long ago.