HZJ80 warm start issue

[AussieKymbo]

G'day.
I have an HZJ80 (1HZ), 10/97.
This last 10-12 months it has developed an annoying starting problem.
1st thing in the morning, easy, starts no problems at all.
But after that, throughout the day, its a pain, takes a good 5-7 seconds cranking over on the starter before it will start, pretty much every time.
Fuel filer changed, twice.
Same issue on both tanks.
Checked for the gauze filter at the injection pump, it doesn't have 1, hmm.
Checked and tested the pre heater temperature sensor, it tests within spec.
Interestingly, if I disconnect this sensor 1st thing in the morning, it replicates the same issue as it has once it's warmed up, but connect this sensor and it starts fine, as it does 1st thing in the morning. Maybe this, or something in this system is an issue, pre heater timer maybe??
Checked both preheater glow plug relays, both tested well.
I'll check the timer once I locate it, apparently somewhere under dash near steering column (RHD Aussie).

Any suggestions?
Cheer's

 

[DivByZero]

Often the problems with these rigs are reversed to yours - hard to get going in the morning but fine during the day. From what you've described, it seems likely the glow system is working as it should. Just look at the indicator light on the dash for the glow plugs, it'll give you an idea of what the sensor+timing system are doing. You'd expect it to be on longer for a cold start, less time for a warm start, but again, it sounds like it's doing its job. If in doubt, try cycling the key back to off and on again a couple of times, that'll fire the glow plugs again, and you'd expect that to stay on less time the second time around, and once it's going off quickly, it should start right up without fuss, if the issue is related to temperature.

If it's not the glow plugs (which it doesn't sound like it is to me), there's only fuel and the starter left. It's not uncommon to have issues with leaks from the injector pump on old rigs, as well as leaks from the primer pump, due to the membrane deteriorating after 20 years. Both of these can get air in the system, causing you to have to crank excessively to get it going. Typically this is again reversed to your situation - hard to start in the morning, but fine once it's going, but it's possible. Have you checked for fuel leaks around your injector pump? What happens if you hit the hand primer pump during the day until it becomes firm, then try and crank? If that fixes the problem, that tells you it's a fuel leak/air in fuel lines problem.

If if's not fuel, that just leaves your starter system. Does it sound like it's cranking healthily? Any different sounds when you try and turn it over in the morning vs during the day?

 

[AussieKymbo]

Often the problems with these rigs are reversed to yours - hard to get going in the morning but fine during the day. From what you've described, it seems likely the glow system is working as it should. Just look at the indicator light on the dash for the glow plugs, it'll give you an idea of what the sensor+timing system are doing. You'd expect it to be on longer for a cold start, less time for a warm start, but again, it sounds like it's doing its job. If in doubt, try cycling the key back to off and on again a couple of times, that'll fire the glow plugs again, and you'd expect that to stay on less time the second time around, and once it's going off quickly, it should start right up without fuss, if the issue is related to temperature.

If it's not the glow plugs (which it doesn't sound like it is to me), there's only fuel and the starter left. It's not uncommon to have issues with leaks from the injector pump on old rigs, as well as leaks from the primer pump, due to the membrane deteriorating after 20 years. Both of these can get air in the system, causing you to have to crank excessively to get it going. Typically this is again reversed to your situation - hard to start in the morning, but fine once it's going, but it's possible. Have you checked for fuel leaks around your injector pump? What happens if you hit the hand primer pump during the day until it becomes firm, then try and crank? If that fixes the problem, that tells you it's a fuel leak/air in fuel lines problem.

If if's not fuel, that just leaves your starter system. Does it sound like it's cranking healthily? Any different sounds when you try and turn it over in the morning vs during the day?

Thanks Nemesis1207.
The glow light has never worked in it, I have owned it for 2 and half years and cant say I have ever seen the glow light, I'll check the globe anyway, wont hurt.
No fuel leaks around the pump or filter/primer.
Yes, tried the prime up until firm, but no change.
I decided to remove that temp sensor this afternoon, just to check, as I'd unplugged it when engine was cold 1st start in the morning and it was difficult to start, plugged it back in and it started fine. I have temporarily connected it as normal and taped it to the loom in the engine bay as an experiment, I took it for a 10km drive, enough to warm it up and got back, switched it off, let it sit for 5 mins and started it, it pretty much started right away, within 1.5-2ish seconds anyway, interesting..
I'm going to take it on a decent run tomorrow and test the start problem again to see what happens, trying all I can think of.
I know diesel nissan navaras are are renowned for this same issue, start fine 1st thing then lots of issues after that, then next day, fine again 1st start.
I'll update tomorrow on what I discover,