Today was the day to fire her up for the first time since March or so, when I started a thread of a delayed hot start issue.
I had two initial fuel leaks, one on a patch on the feed line under the car and another at a fuel pressure gauge I had put in near the fuel rail. Fixed the leak on the line under the car, but just replaced the gauge with fuel hose. No leaks.
Fire her up for the first time… everything sounds great, but no injectors. no clicks, no nothing.
That’s the - Ugggghhhhh…
Had a buddy help check and doesn’t look like I’m getting anything to power the injectors. Rand outta time with a helping hand, so thought I’d post a quick update for feedback.
Gonna hit the archives tomorrow for troubleshooting how to test what thing I screwed up when connecting the injector harness back up, what wire I messed up, etc.
For those that have followed the project, I’d love any feed back on what to check, approach to take, etc.
Thanks!
P.S. Yes, yes, probably did too much at one time, so could be a hundred things, but if I can narrow down to 10 places to start, she runs tomorrow
P.P.S. Of particular note how do I test that this connection is good? see pic…
missing the permanent +V, which is common to all injectors
disconnected / failed crank sensor (2 of those on the V12)
I had the later one morning, no clue what could be going on as the car ran 2 days before
the engine turned, but not fired
disconnecting / reconnecting the rear sensor did the trick
not sure what you want to test on the connecor ?
you could touch the back of each pin using “rear contact test probes” (ie very thin multimeter extensions)
Ok, so after going back and forth, figured it might be helpful to others that stumble across this thread to go ahead and document some things…
First, I did a whole bunch of updates over the last 5 months - new sensors like the CTS, air temperature, probably some others I can’t remember off the top of my head, new oil pressure sender, clean and wrap wires in engine bay, pulled and cleaned injectors, new injector seals, new fuel hoses, patched crimped fuel feed hardline under the car, added pre-sump 300 micron fuel filter, added fuel cut-off valve, new injector connectors, removed A-bank FPR, new B-FPR, and I think that covers most things.
Here’s what I’ve done to date during restart:
Verified that injectors are getting 12v
Verified spark
Verified fuel because it was leaking in a couple of places when I put it under pressure
Verified that injectors click when I do the throttle test - turn car to position 2, manually turn throttle capstan, and I hear it click
Verified it wants to start - when I primed things using many manually throttle tests, and tried to start, it would rumble for a second like it wanted to go which was a different thing when I didn’t pump and it just cranked
Added some more gas and this is where I started thinking…
I’ve got the back-end jacked up so I didn’t have to completely drain the tank, but I did drain out about 5 gallons or so, probably more. I only put back in about 2 gallons. I’m thinking that the fuel sender bobbing thingie maybe thinking there’s no gas, so it’s telling the car not to go.
Question - is that one of the things that the fuel sender does, ie. if it thinks there’s no gas because the bobby thingie isn’t “floating”, will it not allow the car to start, even if there’s some fuel pressure?
I’m going to add more gas today and see what happens, then I’ll move to the TPS, I think…
no the fuel sender won’t do any magic like this : it only provides some variable voltage to the dash indicator
you can run without any fuel sender connected, you’ll miss the dash info, but the engine should start and run
If I understand correctly you have 12V at the injectors but the injectors don’t click?
Either all the injectors are stuck from the car sitting too long (it has happened to me, car sat for a year and a half and 10 out of the 12 injectors would not click, some exercise with very short pulses of 12V freed them up)
Or your ECU does not ground the injectors.
Easy to check with a noid light or a LED with a 600 Ohm resistance
Right, so step #4 verified that the injectors are each clicking. Turn key to position 2, manually engage throttle, listen for click. Did that 12 times or so with helper and listened to each injector.
Then, as part of doing the manual throttle a bunch of times, when I cranked, I could hear a very slight rumble for just a second, which wasn’t there before.
Did that a couple of times, same effect, a rumble that she wanted to go - as if there was just enough go-go juice to fire the cylinders once.
That lead to the next steps and question about fuel sender impact on ignition.
This morning, TPS check… Initial reading at rest was something like 148v on the red wire, so that’s no good😁. Adjusted to proper 0.34v, but haven’t tested yet - only had 5 minutes to check this before the kids took over…
Sure sounds like it’s not getting fuel.
Do you hear your pump working?
Do you hear the injectors click while you crank the engine? (you need two people for this or noid/test light)
Bypass the pump relay to check. Details on the Book.
Fuel filter condition?
No such thing.
Should be able to start even with the TPS disconnected. Not your issue I think.
Fuel filter and pump both have only about 500 miles on them
Don’t hear the injectors during crank, but I’m old and too many heavy metal concerts, so noid light on the way - thank you Amazon! I do definitely hear the injectors click when I manually engage the throttle
Gonna add a couple more gallons of go-go juice this afternoon and check. Then will see what happens and wait for the noid light to show up.
Added go-go juice and then went and double checked everything. One thing that stuck oit was the coils wires. So I dug around in my photos and, while not 100% sure, decided I had the wires wrong - top on the bottom, bottom on top… So I switched them.
Still just cranks…
So, I primed it using the manual throttle, about 12 times turning the capstan and listening for the injector clicks.
Then she fired to life, but only for a second…
Did that a couple of times, same thing… fired to life, soind great, but just for a second.
Got in the car and tried it again, pumping the gas, same thing.
Gotta figure it has something to do with the fuel, but not sure.
Sounds like the engine is running off whatever fuel is injected when the injectors click, but the injectors aren’t working after it starts off of that. D I esnt sound like the ECU is getting a signal that the engine is running. Bad rpm sensor at the flywheel?
This is a Marelli car right?
You need to be 100% sure that you are getting spark and injector click when cranking.
Spark check with a noid light, injector click you can check with a long screwdriver in your ear.
You have to check it when cranking, rotating the throttle capstan isn’t the same thing.
If you lack both spark and injector click, then it’s likely either the crank sensor or the fly wheel sensor.
I’ve written a bunch of posts on these previously, can be found in the archives. Lots of folks have spent a lot of time chasing phantom problems that were eventually determined to be either the fly wheel sensor or the crank sensor. Both must be working and sending signals to the Marelli computer for the Marelli computer to send the signal to the ECU.
My .02.
Bob
I’m pretty sure I’ve mucked up the CPS in some way - either incorrect wiring when I changed the EV1 connector or some how otherwise messed it up. Potentially also the FPS during cleaning when I was working on the loom. Just going down the crank/no start check list…
Will know more tonight.
I do appreciate all the help on this very well documented problem - hence my dilemma after actually creating this thread as to whether I should continue with the troubleshooting steps I was following or just delete it and RTFM…
Jeff - in my opinion, please do not delete your troubleshooting posts as this may well help someone else that comes to the same point as you did and could use your posts as a help - Tex.
The only way to consistently and reliably troubleshoot Marelli no start problems is with an oscilloscope. The expected wave forms are well documented in the ROM. A perfectly serviceable oscilloscope can be heard for less than $100. Off soapbox. And definitely do not delete your posts. It’s all good information.
2 in 1 Handheld Oscilloscope Multimeter, New Update Professional LED Oscilloscope Multimeter with 2.5 Msps High Sampling, Automatic Waveform Capture Function,DC/AC Voltage/Current Test https://a.co/hkL9vca
If it’s the white coacts wire, it’s the wire that runs the signal from the Marelli computer in the right hand passenger foot well to the Lucas ECU in the boot. If it’s cut, no start.
And definitely do not delete your posts. It’s all good information.
