TB42 won’t start

[Lightwork]

Hi, Im hoping someone can spot the obvious reason that I have missed trying to get my ’89 TB42 manual SWB to start.

For a while she has backfired on occasion when you came off the pedal and she idled a little rough at times but fuel economy was good as was power. She is fitted with a Petronix ignitor.

Of late the backfire got worse and she started to miss so I decided to give the whole system a good overhaul. I did this in stages as parts arrived but she gradually got worse until she now simply won’t start.

She turns over on the starter.
I have replaced the coil with a flamethrower, removed the resistor, replaced the dissy cap and rotor (not an extended version), replaced the plugs and leads, put in a new mechanical fuel pump and filter, and put an overhaul kit through the carb.

I have confirmed that I am getting spark at all six plugs, have tried powering the Petronix direct from the battery and checked the voltage at the coil so I am pretty sure it is not electrical.
I have confirmed that fuel is getting to the carby and can see fuel being delivered into the carby when the accelerator is depressed.
I have tested compression (cold obviously) which is good and consistent across the cylinders.
I have checked all the vacuum pipes and made up new ones where needed.
I have cleaned the EGR value which rattles correctly.
The needle and float seemed good when I put the kit through the carby and I have tried another carby from an auto which has been sitting around for years.

But still nothing; she cranks but refuses to start and eventually spits fuel back out through the top of the carby. I am now at a bit of a loss what to try next. Any suggestions would be much appreciated.

[MB]

G’day LW Mate!
Probably no help here as I too became frustrated with petrol donks years ago.
Flashing back, you say mate that you’ve got “spark” (bright blue/white or pale orange) it can matter IIRC?
Your written description so far to my nuffy mechanical understanding still sounds like a fuel issue?
Try cutting off the fuel completely and squirt some ‘start U bastard’ and or CRC/WD40 down its throat to see quickly if it will at the least kick a rotation or two to isolate spark/fuel ?


Sent from my iPhone using Tapatalk

[mudnut]

Plenty of things to check.

[MB]

Fair call Muddy Mate[emoji106]
Maybe a flooding choke situation??


Sent from my iPhone using Tapatalk

[mudnut]

I reckon it was a timing issue at first, but too much fuel will cause a back fire and flooding.

[MB]

http://www.nissanpatrol.com.au/forums/images/imported/2020/07/185.jpg


Sent from my iPhone using Tapatalk

[MB]

If it were nuffy me, I’d start with zero fuel going in and a can of explosive shit squirting in hand to isolate one of two issues :-)


Sent from my iPhone using Tapatalk

[Avo]

Timing,if you have spark,you have fuel and you have compression.....it has to be timing
If that's out it's got everything but not at the right time,try and get top dead centre...take a plug out turn motor over by hand and feel the piston in number 1when it is at the top....yiu should feel it....check timing marks

Sent from my SM-A205YN using Tapatalk

[MB]

Who twisted his sister though, not mentioned?


Sent from my iPhone using Tapatalk

[Lightwork]

Thanks guys. I checked the timing when I first replaced all the electrical components (and still running sort of) and it was good so I am struggling to see how that might be the issue, which leaves the fuel option. I will go try MB's idea.....

[mudnut]

I think Avo is getting at that the timing chain has stretched or jumped a cog.

[Lightwork]

I suppose is is possible Mudnut. I disconnected the fuel feed for the Carby and she almost ran until the fuel left in the Carby ran out so I am suspected it is a flooding issue. So back out with the Carby again. Mind you, I will check the timing as Avo suggests as well. Thanks

[mudnut]

Check the needle and seat. I've had a bit muck stick in the seat, which allowed the fuel to pump in and flood the engine. Also squirt a smidge of engine oil in the spark plug hole of each cylinder and crank it over with the plugs out. (make sure you ground the coil lead). This is because the petrol will have washed the oil off the cylinder walls and lowered compression, adding friction for the starter to overcome. As I wrote, only a few drops of oil, so it coats the cylinder wall as you don't want to hydraulic lock the piston and bend a rod.

[Lightwork]

I checked the timing as suggested and that’s all good. I also took the Carby apart, checked the float and needle etc. She still won’t start.

So, I am back to checking through everything yet again. My understanding of the Petronix Ignitor is that it either works or it doesn’t, is that correct or can there be middle ground in its condition?

I ask because it is the only component in the electrical system which has not been replaced. The spark from the coil to the distributor looks strong and blue, whilst the spark from the distributor seems like it could be a little better. Starting to clutch at straws now!

[mudnut]

Did you try spraying a bit of "Start ya Bastard', down the carby, without the fuel pump on?

Where are you? Is there anyone you can swap components with, to trouble shoot?

[Lightwork]

Yes, I did try that, it sounded like it was going to start and managed a few revolutions but that was about it.

[MB]

G’day LW Mate!
When you mention it tried to start was that without assistance from the starter motor mate?
In theory, if spark is goodish, you should be able to keep her running for at least a little short safe while via carefully metered spray can hopefully.
Otherwise, back to Avo Mate and Mudnut whom runs similar I believe as his daily beast [emoji106][emoji106]


Sent from my iPhone using Tapatalk

[Lightwork]

Yes thats right MB, she would sound like she wants to go, I would release the starter and then she would manage another couple of revolutions on her own before dying again. The revolutions are a struggle, quite slow.

[MB]

Cheers LW Mate!
So so hard for my nuffy noggin to understand now, thinking AVO Mate is on the money for you bloke.
Any chance of a sound recording/video so betterer blokes can hear the shenanigans underway mate?



Sent from my iPhone using Tapatalk

[Lightwork]

Well the plot has thickened considerably...

During this whole saga, at one point the fuel pump killed itself and kindly let me know by weeping oil out as it should to alert me of its capitulation. However, what I have eventually discovered it that is also let a considerable amount of petrol into the oil pan. This made the oil so thin that it appears it didn't have the viscosity to make the valves do their job. Once the oil/petrol mix was drained out of the car and new oil put in, hey presto, she started!

However, its not all good news. Whilst she now starts, she is still missing very badly and belching out white smoke exactly as she was doing just before the fuel pump went and she stopped starting. Given I have changed everything else I am wondering if the valves are not seating properly or the seats have had it and she needs new seats, springs etc. Anyone had experience of this?

Is there a valve kit you can buy, so far I have only found new heads?

[mudnut]

If the white smoke continues after warming up, I think you need a new head gasket.