Won’t Start

[paul_a]

I’ve tried to search and I’ve read up on the topic but still have questions. 2000 450 Chimaera, push the key fob sounds like immobiliser is turning off and then engine will crank over (obviously won’t crank until button is pushed) But the fuel pump is not primming. It’s been standing since early December but normally starts well. I seem to recall that when I started it last time the pump made a screaming noise for a short while before settling down.
Question is the 3-4 seconds the pump should run, what turns it off, pressure or does the ecu just turn it on for the 3 seconds regardless. I can I switch ignition on and see if there’s 12v at the pump or will it only be on for 3secs? Thought it would be good to see if there’s voltage at the pump. 2 new relays ordered which will be good for spares if pumps at fault.
Any help advice appreciated. I’ve recently had a new knee so scrabbling under the car in the cold isn’t ideal.

[Zeb74]

Could be the relay but could also be the pump, try to hit it (gently) with a piece of wood or a hammer (very gently), if you are doing this with the power on, you will immediately here it priming if it was stuck.

[Loubaruch]

My understanding is that the ECU turrns the pump off after the initial 3secs prime. when the engine fires the pump should then run continuously.

The pump terminals get corroded very easily, if you can manage it run 12v direct to the pump before changing relays etc.and see if the pump runs, as Zeb says if it is sticky belting it with a rubber hammer etc. may shift it. If it is sticky it probably needs changing anyway.

Another prone area is behind the passenger seat( lift the carpet by the B post) where connectors to the pump can get damp and corrode.

Edited by Loubaruch on Wednesday 10th January 12:39

[paul_a]

Thanks for your fast reply. I did try tapping it whilst the ignition was on, no change. But I later thought does the ecu turn power off after 3 seconds anyway even if it’s not running.

[paul_a]

Loubaruch said:

My understanding is that the ECU turrns the pump off after the initial 3secs prime. when the engine fires the pump should then run continuously.

The pump terminals get corroded very easily, if you can manage it run 12v direct to the pump before changing relays etc.and see if the pump runs, as Zeb says if it is sticky belting it with a rubber hammer etc. may shift it. If it is sticky it probably needs changing anyway.

Another prone area is behind the passenger seat( lift the carpet by the B post) where connectors to the pump can get damp and corrode.

Edited by Loubaruch on Wednesday 10th January 12:39

I might try to get under in the weekend and test the pump supply whilst my wife turns on the ignition. To see if I get 3 seconds of supply. I can here a 1-2 second buzz from under the bonnet when I turn the key off but nothing when turning it on.

[blaze_away]

The buzz under the bonnet is the ICV(idle control valve) closing. Quite normal and nothing to do with your starting problem

[PabloGee]

Can you run a wire (almost anything will do) directly from the battery posts to the fuel pump?
Alternatively, park your daily next to the TVR and connect to that battery to save digging around in the footwell if your knee is still healing...

Fingers crossed the connections just need a scrub

[Belle427]

A good 12 volt to the pump can be a good idea to prove it, can sometimes also unstick it if its been sat but dont run it for too long.
As suggested things to check are poor connections at the pump and the fuel pump relay, the connections behind the carpet inside the car are another common failure point.
Make yourself a test light out of an old headlight bulb and long cabes, around 5 amps load, its very useful for testing purposes if your on your own and have a Tvr!

[paul_a]

All good advise thank you. It’ll probably be the weekend before I can venture to the garage. I’ll post my findings. Hopefully something simple.

[paul_a]

Can someone just confirm if I’m right.
1. Turn ignition on - power to the pump and runs for 3 seconds before turning off
2. Cranking the engine - power to the pump, to allow fuel for starting.

Thanks

[Loubaruch]

My understanding is that you are half right!

Pump primes for 3 seconds then stops.
When engine fires the pump starts again and continues to run while the engine runs.
The initial prime should be enough to start the car but unless the engine fires the pump will not start again.
I stand corrected.

[Belle427]

The 3 seconds is correct, a pulse is then sent from the ignition circuit to the ecu when the engine is cranking to run it so if that part is missing it wont run.
Difficult to check on your own.
Maybe someone else can confirm this.

Edited by Belle427 on Thursday 11th January 10:25

[bob-bobberson]

Belle427 said:

The 3 seconds is correct, a pulse is then sent from the ignition circuit to the ecu when the engine is cranking to run it so if that part is missing it wont run.
Difficult to check on your own.
Maybe someone else can confirm this.

Edited by Belle427 on Thursday 11th January 10:25

I think there is something in the dizzy that communicates this pulse back to the ecu. I came upon a FB post that showed where this, but never tested it as my problem was down to plugs. Posting for info

Edited by bob-bobberson on Thursday 11th January 12:16

Edited by bob-bobberson on Thursday 11th January 12:16

[Belle427]

All the info you should ever need is here.
http://www.g33.co.uk/pages/technical-fuel-injectio...

[paul_a]

Belle427 that’s some good bedtime reading.
I think I’ve got good news, jacked car this afternoon and cleaned the 2 wires on the pump. They were pretty badly corroded I struggled to get the yellow one off. After a good clean I tried the ignition and the pump came on. I didn’t try to start it as it’s on axle stands. Over the weekend I’ll clean again lower the car down and try starting, but it looks positive.
My knee is now throbbing like a blind cobblers thumb!!

[paul_a]

Update.
So having had the pump prime last week, I thought problem solved. Whilst it’s up on stands I thought a good time to spray some wax protection. Luckily I tried to start it before lowering, guess what no pump!!
I changed the earth spade connector as it looked fragile, no joy. Test lamp to see if any power no joy. I changed the relay (blue plug) and bingo it’s running.
Do you think I should change the other metal relay also. They are currently metal with red line on. I have one as I bought two from Motaclan.

Thanks Paul

[Belle427]

I would personally as the silver ones are original i think, you can always keep the known working in the boot just in case.
Always good to have a set spare.

[davep]

This link points to info that may help people's understanding:
https://www.pistonheads.com/gassing/topic.asp?h=0&...

[Steve_D]

Paul
Please make sure the relay you have used as a replacement is of the correct type. i.e. it has 2 pins marked 87. Not 87a, 87b, 87c.

Steve

[paul_a]

Steve you’ve got me worried now. I bought it from Motaclam, part no TVR M0124. I only fitted the 2nd one today. I’ll pull it out tomorrow and check.

Thanks Paul