No fire up condition

[thenomisf]

Is the fuel pump running ? I am guessing you have pump but injectors aren't firing ?

The ignition switches often go stupid on these cars, so check its making connection on all pins. If not you may be able to feed the ECU a start signal on the right pin to see if it fires up ? Should just be 12v I would have thought.

Also, pull out your fusebox and check the red and blue wire is attached to the post fuse side of the fuel pump fuse. Can cause similar problems!

if pump isn't running

In the boot, in the right hand side (drivers) "cubby box" you can remove the "bowl" and reach into the rear wing. You will find two connectors that come up to the fuel pump.

Measure the positive feed, but make sure the ground of the multimeter is connected to the chassis, not the ground on the connector. You should have 12v.

The ground for the pump is voltage limited by the ECU to slow the pump at idle conditions, use a clip lead or bit of wire to short this ground to chassis ground. This will stop the ECU from being able to control the fuel pump.

[caz4244@essex]

Ive got same problem fuel pump wont run need to check for spark and power next

[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 ?