Starting problems

[n1ck73]

Tried starting the S2 today and found the battery flat so put it on charge. As soon as the battery had some charge in it I noticed an electrical buzzing noise from the engine bay and from both rear wheel arches. Disconnected and fully charged the battery but on reconnection got the same buzzing noise and, although the car starts, its sufficient to drain the battery again once the ignition is switched off and is probably what drained it in the first place. Whatever it is runs from the 15A fuse (bottom right on my fuse box alongside three 25A fuses)and needs to be in place for the car to start so assuming it's fuel injection or fuel pump related....

Anyone know what the problem is and how to sort it?

[Wiz]

Don't think there's anything else that would make a noise at the back other than the fuel pump.
Is the battery ok? if its on its last legs it won't hold a charge long.

I'd check nothing is grounding/shorting to earth as well

Edited by Wiz on Sunday 28th February 19:01

[clarenceboddiger]

Sounds like your fuel pump relay is stuck Closed, ie the contacts have either welded together or its failed otherwise mechanically, jammed etc. As the relay is fed (according to my diagram) with a permanent feed then the ignition would not have to be on for this problem to power the pump.

[mep12345]

Wiz said:

Don't think there's anything else that would make a noise at the back other than the fuel pump.

I'd check nothing is grounding/shorting to earth as well

+1 for the fuel pump being only thing at rear of car that can make such a noise, but this should pressurise the lines and then stop (Does it start and then stop when lines pressurised?), also I would expect ignition to cut this off when switched off unless there is a rogue earth, therefore have you still got (and checked) the dreaded yellow connector in the ignition?

Mark

[n1ck73]

Thanks chaps,

I've had another play around this afternoon. I swapped the batteries over with exactly the same result so its not the battery....
Therefore, everything points to the fuel pump as suggested and this is definitely not being switched off with the ignition...it starts as soon as I connect the negative battery terminal and the only thing that stops it is pulling out the fuse...I'm going to try and investigate whether there is a dodgy earth somewhere but it appears that a previous owner must have replaced the yellow connector as I don't have one of those....
Therefore, are there any other typical problem locations, or any suggestions on what to look for?

[mep12345]

Could the relay be sticking in the on position? Having not traced the wiring diagrams for what they are worth please don't me down.

Mark

[clarenceboddiger]

clarenceboddiger said:

Sounds like your fuel pump relay is stuck Closed, ie the contacts have either welded together or its failed otherwise mechanically, jammed etc. As the relay is fed (according to my diagram) with a permanent feed then the ignition would not have to be on for this problem to power the pump.

The pump WILL run without the ignition on if the relay is stuck in the closed position, it has a Permanent feed, Check the relay

[n1ck73]

thanks for this - is the pump relay one of the ones underneath the fuse box or is it somewhere else? And, sorry if this is a daft question but learning as I go on this...how would i tell if it was stuck and causing the problem - do I just replace it?

[Wiz]

Not sure of the location of the relay but guessing it is in the mess of wiring under the glovebox. Connect the battery and have a look/listen and feel see if any relays are making a noise or getting warm. Then replace.

[beasleyneil]

In my recent experiences there are two relays one red/Brown which I beleive is the fuel injection relay and a yellow one which is the fuel pump relay, these are in the rats nest.If you disconnect ie pull the yellow relay from its base with the ignition on you should here the physical click of the relay contacts breaking as you are effectivly remove voltage from the energising coil of the relay.Again as you reinsert the relay into its base you should hear the contacts making.Just make sure you reinsert the relay correctly into its base as shorting the electrics may offend!!!!!!!

There is probably a correct more safe way to check the servicability of the relay by removing it from the base and applying a direct feed to the coil terminals of the relay,this will allow you to hear the making and breaking of the relay contacts.

Also the fuel pump is only primed on position 2 of the ignition switch for about 1 sec. It should not be on continuosly at this position.

Hope this helps

Neil

[Le TVR]

I thought the 15A fuse there was the switched ignition supply (supplies coils of both fan and fuel pump relays)? The 25A one on the other end of the bottom row was the permanent supply for fuel pump relay + ignition etc.

Does the buzzing stop with the 15A fuse removed? If yes it sounds like the ignition switch itself has a partial short.

[Gerald-TVR]

Le TVR said:

If yes it sounds like the ignition switch itself has a partial short.

Yellow connector?

[clarenceboddiger]

Le TVR said:

I thought the 15A fuse there was the switched ignition supply (supplies coils of both fan and fuel pump relays)? The 25A one on the other end of the bottom row was the permanent supply for fuel pump relay + ignition etc.

Does the buzzing stop with the 15A fuse removed? If yes it sounds like the ignition switch itself has a partial short.

Good point, I missed the fact it stopped with the 15a fuse removed.

[n1ck73]

beasleyneil said:

In my recent experiences there are two relays one red/Brown which I beleive is the fuel injection relay and a yellow one which is the fuel pump relay, these are in the rats nest.If you disconnect ie pull the yellow relay from its base with the ignition on you should here the physical click of the relay contacts breaking as you are effectivly remove voltage from the energising coil of the relay.Again as you reinsert the relay into its base you should hear the contacts making.Just make sure you reinsert the relay correctly into its base as shorting the electrics may offend!!!!!!!

There is probably a correct more safe way to check the servicability of the relay by removing it from the base and applying a direct feed to the coil terminals of the relay,this will allow you to hear the making and breaking of the relay contacts.

Also the fuel pump is only primed on position 2 of the ignition switch for about 1 sec. It should not be on continuosly at this position.

Hope this helps

Neil

Thanks Neil, found the yellow relay hanging under the fuse box and pulling it out stopped the pump buzzing but I didn't really hear any audible click on disconnection or reconnection of the relay. Noticed that it was a little wet as she is not entirely waterproof at the mo and on one of the reconnection attempts there was a series of clicks and the relay felt warm to the touch before the pump kicked in again. Maybe this is a sign of the relay on its way out?

[n1ck73]

clarenceboddiger said:

Le TVR said:

I thought the 15A fuse there was the switched ignition supply (supplies coils of both fan and fuel pump relays)? The 25A one on the other end of the bottom row was the permanent supply for fuel pump relay + ignition etc.

Does the buzzing stop with the 15A fuse removed? If yes it sounds like the ignition switch itself has a partial short.

Good point, I missed the fact it stopped with the 15a fuse removed.

Yes, it does stop when the 15A fuse is pulled. Does this mean its unlikely to be the relay even though it is prob a bit temperamental and maybe a bit waterlogged? (see above).
Removed the underside of the steering column to make sure I hadn't missed the yellow connector and it appears that (buried under several feet of insulating tape) each of the 3 wires from the ignition is wired to the loom separately and not via the same connector....was getting dark so didn't strip the tape off completely but would this be the most likely place to look?

[beasleyneil]

Nick,
Looking at the poor diagrams if you pull either of the fuses (25amp or 15amp) will cut the supply to the fuel pump. The 25amp one should be the direct feed to the pump via contacts in the fuel pump relay (higher amperage)whilst the 15amp controls the fuel pump relay coils via the ignition relay.

If your relay is wet it may be worth an inspection,Take the relay from its loom base.Then with a small terminal screwdriver prize the yellow casing off the relay itself.This will allow you to inspect the inner workings of the relay.If its been wet you will see corrosion inside so therefore my advice would be to change.Also clean the spade contacts of the relay with some glass paper.

It may the the dreaded yellow connector but my moneys on the relay.

Regards
Neil

[n1ck73]

beasleyneil said:

Nick,
Looking at the poor diagrams if you pull either of the fuses (25amp or 15amp) will cut the supply to the fuel pump. The 25amp one should be the direct feed to the pump via contacts in the fuel pump relay (higher amperage)whilst the 15amp controls the fuel pump relay coils via the ignition relay.

If your relay is wet it may be worth an inspection,Take the relay from its loom base.Then with a small terminal screwdriver prize the yellow casing off the relay itself.This will allow you to inspect the inner workings of the relay.If its been wet you will see corrosion inside so therefore my advice would be to change.Also clean the spade contacts of the relay with some glass paper.

It may the the dreaded yellow connector but my moneys on the relay.

Regards
Neil

Oops! does this count as corroded

[orange_dodo]

n1ck73 said:

Oops! does this count as corroded

WOW!

You may need a new one of them

[beasleyneil]

Worth changing me thinks!

Good Luck

[hvdweerden]

cheapest I could find :

https://www.simpsonsupplies.co.uk/prod.asp?product...

Br, Han