No fire up condition

[johnny485]

Gentlemen,

Thank you all for the replies posted re my no fire up condition. I have read and inwardly digested all advice and will report back the outcome of my investigation based on your experiences.

I should be able to arrange a reply post to keep you informed before the end of the week work permitting.

Once again many thanks.

Best regards,

John

[johnny485]

Ladies and Gentlemen,

Here it comes!

Last time posted I had been hit with a no fire up problem. This has now been resolved insofar as the ECU loom had an issue. The issue was Electrolysis! This is a really dirty word as it affects all interconnects in a system where there is air, water and leckkie (electricity). On the main loom that adjoins the ECU loom the feed to the ECU and the Injectors had been badly affected and a connector strip and rebuild was necessary, added to that I ended up repairing the ECU loom by cutting back and re terminating with New EV1 connectors for the injectors , coolant sense, Aux Air valve drive add nauseum......

Now, the engine fires on the first turn but does not sustain so a look in the Fuel pump dept showed 12V to be there but continuous drive. I have been rained off by the weather at present but will update you all as soon as.

My advice to all who run Silvias at this time would be to Check all loom connectors and repair / replace where necessary, it is not enough just to scrape clean the lucar male and female halves....Replace them as they do not hold up well to semi repair effort.

[thenomisf]

Originally Posted by johnny485

Now, the engine fires on the first turn but does not sustain so a look in the Fuel pump dept showed 12V to be there but continuous drive.

+12v is supplied by the ECCS/EFI/Management Relay to the pump + connector when the key goes to stage 2. It is a constant feed.

The control is done one the negative/ground side - which runs back through the ECU which regulates the voltage that is allowed to return through the fuel pump.

If you can download the service manual (available from club-s12), then look at page EC-33 for voltage levels and how to measure. Page EC-12 has a full diagram of the ECCS wiring which helps show how the pump is wired, and EC-66 shows test procedure and ECU pin for pump return.

This has caused me many headaches on my car!

Good to hear you are starting to get it working right again!

[johnny485]

Thanks for the info on the club s12 site....I can't find what you suggested though. I do have a manual downloaded from the UK site but this seems to be lacking in the sections you mentioned. Head scratching time.. I was working on the old gal this evening between rain showers and darkness. I found by your suggestion of grounding the pump supply it runs well. The engine will still initially fire but won't sustain. I have a start signal of 12V and although have had to bypass the starter wire in the main loom it turns over, I was wondering if there is something in the loom thats affecting the operation of the system. Everything is there but it won't sustain, have you seen or heard of any ECU's going funny in your time? Apart from the connectors that I have reworked on the looms previously mentioned I am having trouble understanding the nature of this problems root cause. If you have an epiphany, let me know as I am struggling at the mo.

All the best,

John

[thenomisf]

I have popped the full service manual I referenced up here for you to download http://spafrost.me/nissan-silvia-s12...s12_manual.pdf - it should contain the correct sections

I have my full starter circuit bypassed, as the wiring went bad, so I should not imagine it will stop it from running.

The ECU is a pretty simple old thing, as far as computers go - They usually give up completely and you loose spark/injection all together.

When you attempt to start the engine, how exactly does it behave -does it start, run for a few seconds, then die - fire a few times but die if you let go of the key etc ?

[johnny485]

Hi Nomisfire,

First off, many thanks for your load up of the 200sx manual, it does indeed have more than my manual relating to EC sections mentioned in your earlier
reply.

The original fault (just to give you some history) was a no start after parking. Upon turning the key through acc, ign, all was there, when advancing to S everything on the board just died out. I returned the key to ign and push started her and got home. shortly after I by passed the S portion of the key start and wired a switch into the starter and all ran ok whilst turning the key to ign position ( i could live with that). The progressively she began to get more and more hestitant in starting. In some cases she started and run then during operation on rainy days she cut out. The cut out felt like poor fuel flow and a gradual degradation in power before shutting down.

There was a repair to the block connectors under the washer bottle as the start signal runs to / from the gearbox loom. Shortly after, the ECU loom as previously stated was repaired and new ev1 connectors / pins fitted.

In answer to your question about how long does the engine run; it fires up as a burst for a second or two then dies. If I hold a little bit of throttle it runs for aprrox 2 to 3 seconds max then dies.

Other than checking the super multiple junction and various other related connectors and relays which all check out, that's pretty much where I am at the moment.

Currently I have ordered a raft of new lucas spade and sockets with some new blocks to replace anything else on the affected looms just to ensure there's no chance of any unusual uglies raising their heads. I wish to keep the looms as original as possible whilst minimising to the absolute minimum the need for bypass wiring in the chassis.

I hope this gives you a flavour of what's been going on lately.

Thanks and kind regards,

John

[thenomisf]

I will have a think about this while I am working on my beast this weekend, and let you know if I have any bright ideas!