97 3.5 NL Not Starting

[fjarmabra]

Okay, manned up, cut my fuel line and inserted a tee with a pressure gauge on my supply line next to the injector manifold.

When cranking I get 48 psi (+-2 psi), with the vacuum line disconnected I get 50 psi (+-2 psi) and when pulling a "vacuum" with a syringe on the fuel pressure regular I can get it down to 42 psi. As far as I can work out that checks out. It really tries to start and if I unplug the injector wiring loom connection, it consistently starts for 2 seconds and then dies (when it runs out of fuel). I also partially opened the throttle using the lever on the dash and plugged the throttle position sensor into my spare (reading closed) to reduce the fuel being injected, which seems to help a little bit.

Also took off the intake damper, but couldn't find any moving components.

I bought an injector pressure testing kit since it's looking like injector or injector pulse issue to me. Has anyone used one of these before? I got a kit including a pressure gauge, a few check valves and a bunch of fittings (reducers) without any instructions.

Hoping to have a look at my crank angle sensor tomorrow. I've been trying to come up with a way of doing it without disturbing the timing and crank bolt given my past experience and care taken last time,

Has anyone replaced or rebuilt injectors? Is there an option that will cost me less than what I paid for the car?

[erad]

The fuel pressures you have measured are in the right ballpark. No gauge is exactly accurate, so small variations can be expected. As long as the pressures remain constant, I think you have no problems with the fuel. The leakage into the sump is probably unburnt fuel because you had no spark.

The immobiliser isolates the fuel system. i am not sure if it isolates the fuel pump or the injectors. If it cuts the fuel pump, this could account for the short running time before it dies. Connect a test lamp to the fuel pump supply and see if it stays lit after the engine dies. If it does, at least the pump is getting power and the isolation function comes via the injectors. If the fuel pump supply is cut after a few seconds, try to run a power source directly to the pump. if the engine keeps running, at least you are starting to know where to look, and you know that the injectors are not being isolated by the immobiliser.

An old fashioned timing light will tell you if you have spark. if that goes out as the engine dies, that tells you where to start looking as well. You don't have to be looking for the timing mark at this stage - only looking to see if the spark keeps going. If it does, then you look to see when it is actually firing. Immobilisers do not cut the spark - they isolate the fuel system, so if you are getting a spark, the only thing left to do is to check WHEN it is sparking - not easy if you are by yourself.

[fjarmabra]

Thanks erad.

I recall reading and checking what gets cut by the ignition and recall the injector pulse being the answer but will check again. My fuel pump only comes on when cranking, rather than other cars I have worked on that had it come on with the ignition. I thought that was how these are supposed to work based on forum posts I read here somewhere. I was assuming the ECU works out if the engine is cranking or running, so didn't expect it to run after it stops. Easy enough to check though so will just hook up a permanent power supply for testing.

How long is the fuel pump supposed to stay on after the engine dies?

I tested spark for all 6 leads with it being able to consistently bridge a 22 mm gap in my tester. I will re-test now that I can get it to run for a second or two, but am confident that it is the fuel at this stage given that messing with it seems to allow me to have a hopeful second or two. I clamped on a temporary remote starting switch and got a timing light, so it isn't too bad.

[Scooby]

Have you tried starting it with the exhaust off?
I know you have said that you have checked it but with all the work you have done so far it still seams to me like a air flow problem.
Have seen mufflers collapse before, good for a while then bad.

[stumagoo]

if you have fuel in the oil (and large amounts) its really got to be an injector sticking on.....

The possibilty of a fuel pump issue is weird - as you have already tried an alternative ecu.... the Fuel pump is triggered soley by the ecu via the fuel pump relay.... the ecu triggers it off one of 2 signals - power from the key or power from the alternator saying the engine is running.... thing is the alternator can be all but dead in the water and the fuel pump still runs - in fact I was running soley on the battery with no charge coming out of the alternator and it was running but disconnect the alternator and you will have the fuel pump stop 2-3 seconds after clicking off start....


I still think you have a leaking or stuck injector flooding the engine

[Scooby]

Also with the engine oil make sure you change it when you get it going. Don’t just drain it down to the right level, as it will be thinned out and could cause a bearing to pick up.

[fjarmabra]

Tried with fuel pump running on permanent power without any improvement. Will go and re-test the spark.

I originally took the catalytic converter off (and left it off for most of my tests) but put it back in when it ran for a bit after reassembling the intake with the new power transistor installed. I put that down to it having sat for a long time, which seems to increase the chance of it starting for a few seconds. I washed it out, couldn't identify any lose components, welded up the slightly split seam and blew air through it with ease. I could see through the honey comb component and it looked perfect, so figured it should be okay, especially at idle.

I finally managed to wiggle my boroscope up to the crank angle sensor from both sides (photos attached). It looks like the plate is sitting very close to the front, which is concerning, however I could not spot any obvious damage and still think the timing should be reading worse. That being said the sensor has a slightly raised metal component, which could be touching.

Does everyone think I have to take off my belts, ballancer and potentially timing gear to have a proper look?

[erad]

"Does everyone think I have to take off my belts, balancer and potentially timing gear to have a proper look?"

Sadly, Yes. And it is a pain. The pictures you have posted show a clearance between the blade of the CAS and the sensor, but are the blades truly flat? I managed to bend the blades when I removed the crank pulley to replace the oil seal and didn't know that it was so critical. The CAS cam seems to be located on the belt sprocket quite well, so I think you cam eliminate the bogey of it not lining up with the dowel pin. When I bashed out my cam plate, I set it up on a flat surface and slowly turned the sprocket/cam assembly while measuring deflection of the plate with a dial gauge. There was still a few thous of an inch 'wobble' in the blades, but when I installed it, I had, from memory, about 12 thous clearance on one side and a lot more on the other so I was confident that the blades would not foul the cam angle sensor.

I don't think that you could leave the cam belt in place and carefully rotate the engine, checking the gap with a feeler gauge, because once the belt goes on, you cannot get anywhere near the CAS to check it.

[Kaldek]

WHOA. Holy thread, Batman.

You really need two things here mate:

1. An oscilloscope (a single channel scope will cost you very little)
2. Some T-Pins (you can buy clothing/sewing T-Pins) online cheap

You can diagnose all the stuff you need to diagnose using these two tools. If you enjoy learning, I recommend starting by subscribing to "Scanner Danner" on youtube and watching how he probes stuff like crank signals.

If you can at least get the pulses read from the crank sensor, and then the cam sensor, you can see if it's dead or not.

These sensors are easy to back probe. They are two very similar looking three-pin connectors. I know where they are on my 6A13-equipped Mitsubishi Legnum, but not exactly where they are on a 6G74-equipped Pajero. My own Pajero is the 3.0 litre so it doesn't have a crank/cam sensor, just the stuff in the distributor.


Also if you're in Melbourne I have EvoScan and OpenPort cables so we can pull live data from your ECU. Even without an oscilloscope you could log if there is an RPM signal.

[fjarmabra]

Sorry about the delay in updates and responses, but it has been slow going, a bit of a rollercoaster and my last attempt at writing a post didn’t stick and I lost the lot.

I ended up towing the car 2 hours to a mechanic I trust who I told what I know so far and went to show how I can get it to run for a second or two when it just started and ran. It was idling a bit rough and was sluggish when revving up, but it just ran. We seized the opportunity to confirm the values I had been measuring with fuel pressure, spark strength and timing all being pretty much the same as when it wouldn’t start. I then wiggled the wiring loom to see if it would cut out due to a broken wire, but nothing changed.

Can any of you think of why that may have been the cause for its sudden change in mind regarding running?

After about 5 minutes of the above, he proceeded to play with the throttle position sensor in an attempt to address the idle and the sluggishness. We turned it off and cleaned out the idle plunger under the throttle body and restarted the car. It ran like before. With two mechanics and me looking around the engine bay we noticed that there was a bit of smoke coming from inside the timing cover. We turned it off again to investigate and found that the timing belt had walked forwards and was rubbing on the timing cover. He pulled it apart and found that the right-hand cam pulley was not tightly bolted to the cam and had the locating pin snapped, causing the cam pulley and timing marks to rotate but not necessarily the cam. Well done to those of you that suggested this. I talked to the mechanic who had done the engine rebuild who supplied a new cam, cam pulley, head gasket, seals and rocker cover gasket. The valves had made contact with the pistons, but it looked very minor and the current mechanic checked it and told me nothing had been damaged. The cam angle sensor and crank angle sensors both looked good and had clearance from the plate.

We got the parts last week and installed them. We tried to start it before full assembly (everything excluding the alternator, AC compressor, power steering pump and cooling system) to allow access to the timing components if we needed to and it unfortunately behaved the same as before: fired for about a second on initial start and then would not start, fire or run while fuel pressure, flow, injection pulse, timing and spark all look good.

So basically back to square one unless you know of a good reason why the auxiliary gear we left off would not let it run.

The current mechanic is suss on the immobiliser but I can’t find agreement on the internet what it would cut out (injector pulse, fuel pump or spark). My only two possibly plausible ways of thinking that one through would be either 1. The immobiliser chip has some sort of charge that is drained during the initial use and doesn’t have enough capacity until you let it sit for a bit; or 2. The immobiliser receiver has an intermittent power supply that causes it to re-check for the immobiliser signal when it is established, but I haven’t noticed any power supply cuts. Is there a way I can supply the immobiliser system with a secondary power supply or better yet bypass it?

I, unfortunately, am not in Melbourne Kaldek, thank you for the offer but can try to get an oscilloscope as recommended. Although buying a new crank angle sensor may be faster and I once pulled out the plug of the cam angle sensor while it was running and while being rough, it ran, so that’s unlikely to be it. I am starting to get desperate for this vehicle as my leave is fast approaching and I have stretched the work car usage as a result of this car issue already.

I really thought the broken cam pulley locating pin was going to be it and my current mechanic seems stumped, so am more than all ears regarding what anyone else thinks. I have messaged the mechanic that did the engine rebuild that works on these cars a bit, but nothing yet. Any ideas?

[erad]

Silly question, but they are easier to answer than sensible ones....

Do you have the high tension leads on the correct position? I ask this because, among my other mistakes, once after doing a timing belt change on my NL, I got the leads wrong. It ran on petrol but very poor power and occasionally it backfired. On gas it backfired massively. I had logically connected the HT leads to the coils as I would do them if I designed the engine. WRONG!

To my shame, my wife came out after a couple of hours and asked what those numbers were on the intake manifold. They were well back from the coils and I said that they would be a part number. Closer inspection showed the "part number" to be from memory 143625. A light bulb flickered somewhere and I connected the No 1 and No 4 leads to the coil marked 14. Similarly Nos 2 and 5 to the coil marked 25 and likewise 3 and 6 to No 36. Turned the key and VROOM! Smooth as silk. It took a long time before I was allowed to forget that one. The engine did run, but very roughly and it smelled strongly on unburnt petrol. It isn't easy to check the HT Leads, but try to follow them through and see if they are connected to the correct position.

[fjarmabra]

Thanks erad, that's a good point. The mechanic and I both checked them and agreed they were right but I will double-check them although will have to wait until the next time I drive out to the car, which should be Friday.

We seem to be at a point where it will have to be something like that as the other things have been double or triple checked.

I am toying with the idea to get a 4 door that has the same engine to get me around over Christmas and allow me to compare everything to a running model while also being able to swap out parts to verify they are not the cause, but I am getting a lot of eye rolls when I went to sanity check this approach with some of the people around me. With the mechanics out of ideas and increasing desperation for some wheels, I don't know how else I can make some decent progress.

My main worry would be if there are any differences in those year models that will make them non-compatible for part/engine swapping and voltage checks at plugs etc. Do I need to look out for anything else than 3.5 l SOHC from 1996 to 1999? I know there is a DOHC but wouldn't be getting that.