Z18ET won't run/idle

[Mikewazowski]

So I drove to Appco today in the 610 to get new wiper blades. Everything run sweet going there, but when I came out to leave after a while I fired her up and after a few seconds the Z18 spluttered and died. I tried to turn it back on and the engine would just turn over but wouldn't fire. It fired half-assed once or twice but never really got running.
We left it there and went to get a car to tow it with. About 40 min later we got back to the 610, I put the keys in the ignition and it fired up straight away. It ran for probably 20 - 30 seconds (long enough that I thought it was sweet) and then the idle dropped down and it died again. It started once more for a couple of seconds then died. Then it just turned over and wouldn't start anymore.
I've towed it home and it is in the garage at the moment. I'm just waiting for a bit and then I'll have a look at it.
I had a quick look and nothing seemed out of place:
- spark plug/coil leads all connected
- doesn't seem to be any boost leaks
- I can hear the fuel pump running

Any ideas of things to check would be great. I've got a few ideas but would be good to hear any thoughts you people have

Thanks in advance

Michael

[85_Z31]

Hi Mike,

I would Assume the Z18ET is 1800 Overhead cam & ET for Electronic Fuel Injection & turbo ?

If so I would be looking

*Crank Angle sensor ( inside the dizzy undernearth the metal covering plate undernearth the rotor )
*AFM or MAF > these are notorious for causing weird running condition older Nissan/Datsun EFI motors
*electronic ignition Ignitor ( actually a transistor ) that fire's the coil
* Coils don't usually go bad, if its got a crack in it though that is definitly a problem

If it is none of these then it could be bad news for the ECU, but that would be rather rare and unlucky.

My Nissan Factory Dealer service manual outlines steps on testing these, although for a different motor the principles are the same.

One thing that stung me before was ASSUMING it was ignition.

Fuel Filters get blocked - cheap to replace - and fuel pumps get old and crap out sometimes.

you can also put a screwdriver on each injector & put your ear on the end to see if its ticking

If the injectors are not ticking then there won't be any fuel getting to the engine > this is where it gets tricky as if the crank angle sensor is not triggering the ECU won't know to pulse the injector.

Terminals on the injectors can also get pretty corroded, you would never know unless you pulled off the plug and had a look - worth checking cos its free but it probably won't be that


Hopefully this helps Mike, I Spent 5 months going over all this crap and it turned out to be petrol in the oil causing it go rich and fouling spark plugs which only make it get progressively worse. Wasn't even ignition related.

that brings me to my last point, its very unlikely you have lost compression but its easy enough to get a gauge on there and see what its doing - if anything just so you know

Can't assume anything here, these problems can be a real bastard on EFI motors- much worse to track down than points dizzy's and Carby's

[datsunboy]

do you have any fuel left?

have you tried pulling the plugs out and seeing if they're covered in heaps of black crap? give them a good clean while they're out anyway

[Mikewazowski]

Thanks for the replys guys. To answer a few questions:

The fuel pump is only a few months old so I hope it isn't that (although who knows).
Yeah it has plenty of gas in it.

I just went out to the garage to start having a look at a few things you suggested...turned the key...and it fired up with no hesitation. Ran sweet as all the way through the cold idle and continued to run fine once it warmed up!
Really weird but it seems to be running all good now?! I'll take it for a drive in a bit and see what happens. Hopefully it was just a blockage or something that has buggered off?

[classicdat]

Had that once with a pickup truck. The problem was some insulation tape in the fuel tank, it would suck up on the end of the fuel pick up every now and then, completely running the engine out of fuel, then when the pump stopped it would normally float off allowing the fuel to pump through the next time you started it. Had me beat for months if not years, tank was clean, no moisture, no obvious reason.
Blow back through the fuel line, costs nothing, might dislodge a partial blockage.

[torqued]

I had a car once of "such and such description" and once hot if you turned it off, it wouldn't start again until stone cold.

I never found the problem as Im a tight ass and didn't want to spend money on it. I disconnected the ignition switch so i could leave the car running, pull out the key then lock it while i ran into the shops etc.

My theory on the problem was the ignition module :reason , when something is hot it causes resistance and during start up it would require more pulse to run though it

probably not relevant in any way though

[85_Z31]

Mike, is it a Hotwire Mass Airflow Meter or is it the Flapper spring type ?

Nissans are usually hotwire, perhaps some shit got on the element and caused it to run bad ? might be worth a look in your airbox to see how clean it is.

Dosn't take much to upset the Hotwire type > the older ones are notorious for being intermittant

[datsunboy]

older nissan's are all flapper type AFM;s
the new ones from the SR/CA were hotwire type

[85_Z31]

I always thought most of the Nissan ECCS stuff ran hotwires, my 85 Z certainly does but it must be the exception of the bunch.

I actually keep a spare one in the boot they seem to cause issues that often.

Any other idea's mike ? is it still running ok or has it had its moments again ?

[Mikewazowski]

Hey guys, have been busy with the car lately. After my last post it seemed to be working again but then when I tried to start it the next day it wouldn't start and run. I checked the engine bay while the fuel pump was running and found a fine jet of fuel coming out of one of the fuel lines between the fuel rail and injector number 1. I inspected all of the fuel lines which feed the injectors and they all looked pretty terrible. I figured that the fuel leak would be stopping the rail from getting up enough pressure for the injectors to work. Turbo and Diesel Automotive in Hamilton (awesome place) put new lines and pincer caps on my injectors and I put them back in the engine. After that was done it still wouldn't start
I took the spark plugs out and they all looked really fouled. I cleaned them with some sandpaper and put them back in. That seemed to fix it and it was running fine when I drove it for about 20 min, but when I stopped after that it seemed to have a lumpy idle.
I think maybe the plugs are fouling up again?
I've got a suspicion that my thermostat might not be working as it should (will try and replace tomorrow), would this be causing it to run rich and foul the plugs up?

If anyone knows the answers to these that would be choice:

- Does the Z18ET use the same thermostat as the Z18E? (Or does it have markings on it to identify what type it is?)
- Is there a better way to clean spark plugs than just to rub with sandpaper?
- Most importantly, does my theory on cold running = rich plugs sound plausible?

P.S. My AFM is the old gate-style like the FJ20E has