Big Fuse location.

[Mark.]

I'm suspecting the big fuse, all electrics working except the fuel pump doesn't prime when immobiliser is disarmed. Or a wire dropped off the pump - funny how car was behaving perfectly normal when I put it away

I seem to remember it being on the chassis rail under the starter motor?

[Harrytsg]

Dont forget to try the reset button above the glove box.

The large fuse location is as you describe (on mine), though I've read on here that it can also be near the battery IIRC.

[JonathanT]

On my '99 450, the 100A fuse on the chassis rail sits between the alternator and the battery. If the battery is fully charged, this should not prevent any other electrics working - "all" that happens is that the battery will go flat.

[Mark.]

Harrytsg said:

Dont forget to try the reset button above the glove box.

?

[Mark.]

JonathanT said:

If the battery is fully charged, this should not prevent any other electrics working - "all" that happens is that the battery will go flat.

OK, so I'm half a bottle of Rioja down, but I'm not sure I follow this.

[scotty_d]

Mark. said:

Harrytsg said:

Dont forget to try the reset button above the glove box.

?

The inertia switch i has like a ball bearing in it , In the event of a crash it cuts the fuel pump off i had mine trip on the poor roads round my area before worth a try if its only the fuel pump thats down. Just pop the 2 screws on the Glove box and have a feel for it a big rubber button. If it's tripped it will push to the closed position again.

Scotty

[Goaty Bill]

Mark. said:

JonathanT said:

If the battery is fully charged, this should not prevent any other electrics working - "all" that happens is that the battery will go flat.

OK, so I'm half a bottle of Rioja down, but I'm not sure I follow this.

clicky for picy

What he means is, well what he said

If the 100 amp fuse goes, in my experience (and everyone else's I believe), the battery goes dead. That's it.
Everything else works as normal.
By that I/he means, if you throw (gently) a new battery into it, the car would behave as normal, until the battery dies again.
(we drove 40 miles on an RAC jump pack following a 100 amp fuse failure - long, very long story)

This seems to point to you having some other problem, or some other problem as well?
Inertia switch reset (as per Harrytsg) sounds like something you should push just in case.
And, as you suggested; the wiring / fuse to the fuel pump.
Of course, if the battery is very dead, then the fuel pump won't prime, but I am assuming you tried jumping it?

Good luck.
Keep us in the loop.


mmmmmmm Rioja

[Mark.]

Chaps, thanks will take a look at the inertia switch, thing that get me is car was running fine when I put it away.

Now I've finished the Rioja and had a sleep I understand the other bit. Hard to tell though as car is plugged in to a conditioner so will always be topped up.

So course of action (when it's not so bleedin' cold!

1. Inertia Switch
2. Check fuses.
3. Check wiring to fuel pump
4. Have a look at big fuse.

Cheers chaps!

[5.0ltr]

Try fuel pump relays, mine went down whilst parked in garage. As others have said 100 amp fuse blowing just stops the battery charging.

[Podie]

JonathanT said:

On my '99 450, the 100A fuse on the chassis rail sits between the alternator and the battery. If the battery is fully charged, this should not prevent any other electrics working - "all" that happens is that the battery will go flat.

Helpfully the Griff has one by the diff..! WTF?!?

Took us ages to find that one...

[M@H]

5.0ltr said:

Try fuel pump relays.

Yep, thats what it sounds like to me - its the blue one for the pump IIRC. (this being one of the two that float about around the battery and are free-wired off the ECU loom.)

[Mark.]

Thanks, relays sounds good port of call. Typical that I reverse the car in to the garage on that side so have approx 5mm gap between door and wall.

Headlong in to footwell I go!

[spend]

Fuel pump only primes for a second when you first switch the ignition on, itthen doesn't run at all until the engine is firing.....

Are you sure it isn't working as it should?

Jumpering the fuel relay (blue socket) across the opposite perpendicular terminals should make the pump run if you need to test.

[Mark.]

Absolutely sure it's not working as it should.

[Colin RedGriff]

If the fuel pump isn't priming when you disarm the immobiliser it could be an immobiliser fault. Try running a direct feed from the battery to the pump to see if it will run (prove that the fuel pump works).

[Mark.]

I wondered about the immobiliser but the engine turns over, and if I don't disarm the immobiliser the engine doesn't turn.

[Ribol]

Mark. said:

I wondered about the immobiliser but the engine turns over, and if I don't disarm the immobiliser the engine doesn't turn.

Keep in mind that the immobiliser might not be working properly on all "cuts" - if that makes sense?

[Mark.]

Indeed - but it's the newest bit of the car pretty much. Replaced by our local Guru a few years back. I'll be suspecting other things first.

[M@H]

Relay.
its the Relay.
its always the Relay.

thats better

[Podie]

M@H said:

Relay.
its the Relay.
its always the Relay.

thats better

Unless it's the...