Fuel pump relay ??

[170sport]

Hi I got a 89 sport and it's been running fine, but the last two weeks it's been stood, went to start it toady, and the ignition lights come on but it won't crank, neither does the fuel pump prime. You can't hear it humm. Battery is fine etc..., so I pulled to drivers speaker out and reached in and pulled out the big relay box which was smoking so I unplugged it. But I know this is for wen u have an accident it unlocks the doors, but does it also control the fuel pump/ignition? Cuz before all the rain we had it was ok the car ran fine. So now that relay is dead and buried im just curious to know if it also controls ignition and pump? As it would make logical sense if it did but I don't know if it does or not?

If it doesn't then where would the starting and fuel pump relays be located?

Thanks

[Grrrmachine]

http://www.e30zone.net/e30zonewiki/index.php/Relays

[daimlerman]

Sounds like you have found the central locking relay to me!
Is the hole it lived in full of water?

Engine not cranking,is the battery charged?
Fuel pump will not switch in until the engine ECU sees the engine turning.

[170sport]

http://www.e30zone.net/e30zonewiki/index.php/Relays

Thanks bud! I'll take a look at the relays and see whats happening. I did have a look on the wiki but couldn't see it, obviously I wasn't looking hard enough

[170sport]

Sounds like you have found the central locking relay to me!
Is the hole it lived in full of water?

Engine not cranking,is the battery charged?
Fuel pump will not switch in until the engine ECU sees the engine turning.

Yep it was full of water haha! Not encountered this issue with them yet but I have now, yeah that big relay was hissing and smoking needless to say its ruined! But I assume this controls just the central locking?

As for the engine, no its not cranking you swtich the key over to 'start' but nothing happens, no clicking nothing! Its as if there isnt a starter motor fitted?? Battery is fully charged. Perhaps theres something wrong with the main relay under the bonnet but before when the engine was running if you switch the ignition on until all the lights came on you would be able to hear the fuel pump prime up, but not now??

[Grrrmachine]

I've just realised that the image in the Wiki describes a pre-1987 car, so disregard it for the moment. The central locking relay burning out shouldn't be the cause of your non-starting problems.

However, you can work through the Wiki Troubleshoot, and let us know how you get on.

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

Go for the Diagnostic Plug Test to start with, since your car isn't even cranking.

[170sport]

Oh is it? I'll ignore that then, yeah I was gonna have the wiki in one hand tomorrow and my e30 in the other tho I have just literally done abit of research else where and the 'main' relay located in the engine bay apparently controls numerous item on the car, the 3 they listed were starter control, fuel injection supply, heated screen. So I'll put a meter on the heated screen tomoz and see if it's working, and if it's not then I'll go for a main relay...

[Grrrmachine]

The only relays that matter are the DME relay and the fuel pump relay. The fuel pump relay won't work if the DME is knackered, but neither will stop your engine from cranking which is your real issue here.

The engine works on a chain; Part A feeds info to Part B which makes Part C do something to Part D, and so on. If nothing at all is working, you go to part A, which in this case means bridging pins 11 and 14 of the diagnostic plug before you do ANYTHING else.

[170sport]

Sorry mate, DME?

[Grrrmachine]

DME

http://www.e30zone.net/e30zonewiki/index.php/DME

But don't worry about that yet. Just follow the Wiki Troubleshoot and tell us how it goes. If you jump forward two steps, you'll just create more confusion.

[TPS]

Digital Motor Electronics, I think.

[daimlerman]

This fitted with an autobox?

[daimlerman]

Sounds like you have found the central locking relay to me!
Is the hole it lived in full of water?

Engine not cranking,is the battery charged?
Fuel pump will not switch in until the engine ECU sees the engine turning.

Yep it was full of water haha! Not encountered this issue with them yet but I have now, yeah that big relay was hissing and smoking needless to say its ruined! But I assume this controls just the central locking?

May be an idea to clear the cill drain point,before it rusts it's way out.

I would also be making sure that the sunroof drains are clear,the front holes from the sunroof tray have rubber tubes into the cill area...
Rear end of the tray drains,or should drain,into the rear of the cills,then onto the deck,of course!

[170sport]

This fitted with an autobox?

No it's manual mate...

[170sport]

DME

http://www.e30zone.net/e30zonewiki/index.php/DME

But don't worry about that yet. Just follow the Wiki Troubleshoot and tell us how it goes. If you jump forward two steps, you'll just create more confusion.

Ok, yeah I will keep you guys posted. Gonna run some tests tomorrow and start tracking down the prob...

[daimlerman]

This fitted with an autobox?

No it's manual mate...

So that rules out the auto inhibit circuit,then!

IF the engine is not cranking,there must be a break in the black/yellow starter signal wire.This starts at the ign switch as plain black,switches to black/yellow,runs via a connector behind the glovebox(where the auto inhibit circuit connects for an auto)to C101,then on to the starter.

[Rav335uk]

DME relay is thw white one underneath the cover by the headertank.

[170sport]

Sounds like you have found the central locking relay to me!
Is the hole it lived in full of water?

Engine not cranking,is the battery charged?
Fuel pump will not switch in until the engine ECU sees the engine turning.

Yep it was full of water haha! Not encountered this issue with them yet but I have now, yeah that big relay was hissing and smoking needless to say its ruined! But I assume this controls just the central locking?

May be an idea to clear the cill drain point,before it rusts it's way out.

I would also be making sure that the sunroof drains are clear,the front holes from the sunroof tray have rubber tubes into the cill area...
Rear end of the tray drains,or should drain,into the rear of the cills,then onto the deck,of course!

Yeah I think I might do that aswell tomoz, the little pocket wasn't 'full' with water it just seems as if water has tracked into it gradually filling the really box up over time. As its quite rusty and corroded.

But I'll run a line down each side and try an clear them abit more to try and prevent it again.

Cheers for ur help !

[170sport]

This fitted with an autobox?

No it's manual mate...

So that rules out the auto inhibit circuit,then!

IF the engine is not cranking,there must be a break in the black/yellow starter signal wire.This starts at the ign switch as plain black,switches to black/yellow,runs via a connector behind the glovebox(where the auto inhibit circuit connects for an auto)to C101,then on to the starter.

I've had the steering coloumn apart today to change the ignition barrel so maybe I might have disturbed something? I'll take a look at that area again aswell.

[170sport]

Although this engine and fuel prob was happening before I changed the barrel but I guess it's still worth a look...

[daimlerman]

Although this engine and fuel prob was happening before I changed the barrel but I guess it's still worth a look...

Could,just,be a problem with the ign switch,then.
That's the orange plastic thingy that clips onto the back of the barrel.

Un-clip it,and use a small flat-bladed screwdriver to operate it.

[170sport]

Yeah that's ok bud cuz all the ignition lights come on and fuel gauge move etc...just like normal when you go to start up. Just when you then turn the key into the final 'engine start' position. That's when nothing happens. So I then need to cycle off then cycle back on again, but still nothing. I'll run some tests tomoz and start digging I didn't get the time today. I'm hoping its just a relay, as it ironic the starter motor and fuel pump are both dead simultaneously....

[Grrrmachine]

The fuel pump shouldn't be running at the start anyway, since it's activated by the DME which doesn't switch on until the engine is spinning. So there's nothing ironic or coincidental.

Daimlerman's on the right path regarding the black or black/yellow wire to the starter, which is what the diagnostic start is supposed to confirm.

[170sport]

Fuel pumps should engage first, the engine doesn't start spinning before the pump is engaged. Because fuel needs to be pressurised to the rail quickly so the engine starts immediately. Why would the engine 'spin' and, (all be it afew seconds) then wait for the pump to engage and pressure fuel before the engine can start? Doesn't make sense? The driver would need to keep the starter engaged for longer until the fuel system is up to pressure. Even says in ur wiki, quote: Operation
Two pins of the DME relay, 30 and 86, are connected directly to the Battery through an unfused red wire and are therefore hot (constant 12V) at all times.
Pin 85 is connected to the ECU; usually pin 36. When the ignition is turned on, the ECU receives 12V at pin 26. It will then switch pin 36 to ground which will activate the DME relay.
When the relay activates, it will connect pin 30 to both pins 87, supplying live power to the Fuel pump relay, the injectors, the ABS if fitted, and back to the ECU at pin 37.

[170sport]

Disconnect your fuel feed to your fuel rail and turn ur ignition on, you will get lots of fuel coming out and the crankshaft wouldn't have turned a single degree.

[Brianmoooore]

....... the DME relay.
When the relay activates, it will connect pin 30 to both pins 87, supplying live power to the Fuel pump relay, the injectors, the ABS if fitted, and back to the ECU at pin 37.

The DME relay supplies power to the fuel pump relay, ready for it to be activated, but does not turn it on. It still requires turning on by the ECU, which it will not do until it sees pulses from the crank position sensor - when the crankshaft is being turned by the starter motor.
Sufficient residual fuel pressure should be maintained in the fuel rail between starts at 'normal' intervals, without assistance from the pump.
There is no relay fitted at the factory, on manual cars, which has anything to do with the starter motor, except for a relay that is an integral part of the motor.
There may be a relay, dealer fitted or aftermarket, which is part of an immobiliser.

[170sport]

But how can the DME relay supply power to the fuel pump relay, yet the fuel pump then does not activate? Providing everything is working ok once the relay is energised the component will start working? Your saying the engine ecu 'switches the pump on and off' once the fuel pump relay is engaged? But that sounds alot like can-bus wiring?

[Grrrmachine]

The wiring for the fuel pump is quite basic. One wire comes from the fuel pump relay, and is controlled by the DME relay. The other wire isn't ground; it goes back to the ECU.

The DME relay supplies permanent 12V, but if the ignition is on and the engine is NOT spinning, the ECU wire will also be set to 12V - therefore there's no potential difference to supply charge.

When the CPS pulses, the ECU will switch its fuel pump wire to the ground rail, which activates the fuel pump.

It's a safety design, to cut the pump off when the engine stops spinning in the event of a crash.

[daimlerman]

Disconnect your fuel feed to your fuel rail and turn ur ignition on, you will get lots of fuel coming out and the crankshaft wouldn't have turned a single degree.

Errrr,no!

Just the held pressure in the line will be lost.

Think logicaly,if the car is crashed and a fuel line ruptured,having fuel sprayed out of it will cause a fire.Therefore,no engine turning,no fuel pump running.

It is possible to make the fuel pump work without running the engine,once we have your engine cranking solved,if nesessary we can tell you how to do this to test the fuel pump and it's wiring.

[170sport]

Ok chaps the engine is now running, I will tell you wat I found in abit. Just got to pop out.

[170sport]

Ok right take a seat, I checked the main engine relay and the fuel pump relay as indicated on the wiki and I'm not sure the middle one is the fuel pump relay as I was assuming the DME relay was at fault because the ecu wasn't energising thus cranking the engine, but anyway I bridged 87-30 on the main relay seat and the fuel pump suddenly burst into life, went to go and start the engine - nothing. I thought well perhaps it needs a closed circuit from 86-85 aswell as 87-30 so I bridged that aswell - nothing. Then assuming what I thought was the centre relay which runs the fuel pump, 'apparently as indicated by the wiki' I thought well this relay obviously works so I fitted it in the main relay housing. At least then the engine should crank but obviously not start with a functional relay yes? - no it didn't crank.

So thinking it prob wants a signal aswell from the, 'so called fuel pump relay' I went to bridge 87-30, now technically your prob thinking, well the fuel pump will now activate? As its a direct feed - nope it didn't work at all. Now I'm thinking wtf? The middle one can't be the fuel pump relay? So pulled back out the main relay and now we have the left hand and middle relay removed. I bridged 87-30 on the main relay base and the fuel pump burst into life! How can the fuel pump run if the centre relay is removed? As wiki indicated.

So I thought 'maybe' both relays have simulatiously gone tits up, slim chance but It can happen. Knocked up some Enxtention cables quickly and realising 30 is a direct feed from battery to earth in 87 connected 85-86 on the relays and plugged in 30 then earthed on 87 just to hear if they are clicking? Yep they are both clicking. Ok let's check feeds from the ignition to relay bases can't remeber which it was 85 or 86 but anyway the moment the key was turned there was 12v at the bases. Well what the hell is wrong? Plugged all the relays back in got some one to flick the ignition on so I can hear if their clicking - no clicking.

Now I'm getting upset, how the hell can the relay bases hi and low feeds both be working, relays are both working yet when plugged in nothing happens?!?!?!? It's like draining a 10l fuel tank and wen u put it back in it only takes 9l ???

So giving up with those relays I remeber you guys saying about steering colum wiring, now I pulled the steering column apart yesterday to replace the ignition barrel assembly but this was AFTER the none starting issues. Now there's two white blocks which piggy back sat ontop of the steering tube yeah? Pulled this off to have a nose couldn't see much that would cause any major issues, unplugged them plugged back in gave it a wiggle, pulled out the single black and yellow plug had a look - ok plugged back in. Clipped it all back up.

Checked battery, yep 12.2-3 volts, thought lets check fuses again incase I've popped something whilst poking around all fuses ok, only thing i found where the fuel pump fuse is its suppose to be a 7.5amp and a 15amp fuse was fitted. So changed it for a 7.5amp.

Flicked the ignition on went to start it and - FML !!! It cranked !!! Then fired !!! Engine running I'll be f*cked!?!? Only thing I can think of is that maybe it might of been an iffy connection on the column blocks? It still doesn't explain why the relays weren't activating when plugged into their bases? And the middle one must control something else? Cuz bridging 87-30 on the main relay activates the fuel pump with the middle relay removed.

But anyway it's running now.

[Brianmoooore]

Do you listen to anything we tell you? THERE ARE NO RELAYS ASSOCIATED WITH CRANKING THE ENGINE.
The three relays under the cover easily unclip from their mounting bracket, and can be replaced in any order, so position is not a reliable indication of their function. The one that activated the fuel pump when you bridged 30 and 87 is the fuel pump relay, whatever position it's in on the bracket.

If you linked 85 and 86 on a relay base, you are lucky you haven't done serious damage, such as cooking the engine loom or destroying the engine ECU.

A 15A fuse fitted in position 11, instead of a 7.5A one is often an indication of an intermittent fuel pump problem, but it may have already been replaced, of course.

Whatever your problem was, it's somewhere in the location of the steering column; either the plug and socket on the column not pushed together properly, or a faulty ignition switch.

[Grrrmachine]

Can you show me which parts of the Wiki you're referring to, as you've definitely misunderstood something. Neither the DME relay nor the ECU itself have anything to do with the engine cranking, so if there's a part of the Wiki that makes you think there is, then I need to know so that it can be amended.

Also, if your battery is only showing 12.2V, something's not as it should be:

http://www.e30zone.net/e30zonewiki/inde ... ge_Battery

And did you even try the Diagnostic Plug start? If you had, you'd have saved yourself all that messing around with relays in the first place.

[170sport]

Brianmoooore - perhaps you could explain the path from the ignition switch to the starter motor solinoid?

[Brianmoooore]

Black wire from the ignition switch, changes to black/yellow at the plug and socket clipped to the steering column, goes across behind dash to a single pole plug and socket above the glove box (where the inhibitor plugs in on an auto), then goes into the duct at the back of the glovebox that leads up into the fusebox.
The wire passes straight through the fusebox, unbroken, then goes to the C101 20 pin engine loom plug on the bulkhead, near the fusebox. It passes through pin 18 of this plug and socket, into the engine loom, still black/yellow, then splits at a joint, with one wire going to pin 11 of the diagnostic socket, and the other going to the 8mm stud on the starter solenoid.
At any point along this path, the wire may have been intercepted by an aftermarket immobiliser fitter.