Fuel Pump.... The Saga Continues

Post Fri Mar 10, 2006 7:57 pm

Don't assume that because you've fitted a different fuel pump, that it's a good one. It may have been sold to you in good faith, but fuel pumps don't like being left dry in my experiance, and a pump which was working fine when removed from its original home may not work reliably when fitted to a different car if it's been stored for a while.
Remove the pump relay, bridge pins 30 and 87 of the socket, and see if fuel is pumped from the fuel line when you remove the hose from the fuel rail.
If you don't get any joy, then take a 12V 5W lamp with a couple of bits of wire attached, and connect them to the plug on the fuel pump.
Next, bash the rim of the pump with a hammer. This may start it up, confirming a dud pump.
Don't forget to remove the link when you finish, and don't let the pump spray fuel every where.

Post Sat Mar 11, 2006 4:31 pm

the first fuel pump was ok mate, till i fried it !

Post Sun Mar 12, 2006 9:01 am

Car is gunna get towed home today, and im gunna check things, before i call in a Mechanic

Post Sun Mar 12, 2006 3:07 pm

Well couldnt get it home, coz there was no Tow Hook

Post Sun Mar 12, 2006 6:20 pm

Have you checked on the left hand side of the boot? Mine has a little storage pocket with the towing "eye" in it. Most breakdown services should carry towing eyes.

Post Sun Mar 12, 2006 6:30 pm

I had a very similar problem to this on my 325i last year. It turned out to be a faulty crank position sensor. Same symptoms can occur if the sensor is dirty. The fuel pump doesn't fire up if the ecu is not getting a signal from the crank sensor.

hth.

Taylor.

Post Sun Mar 12, 2006 9:31 pm

Taylor325i wrote:I had a very similar problem to this on my 325i last year. It turned out to be a faulty crank position sensor. Same symptoms can occur if the sensor is dirty. The fuel pump doesn't fire up if the ecu is not getting a signal from the crank sensor.

hth.

Taylor.

Taylor mate, is it easy to get to, to clean ?

Post Sun Mar 12, 2006 9:35 pm

i had the same prob after my fuel pump was knacked

you checked the fuel filter? sorted my prob out

Post Sun Mar 12, 2006 10:07 pm

Taylor325i wrote:I had a very similar problem to this on my 325i last year. It turned out to be a faulty crank position sensor. Same symptoms can occur if the sensor is dirty. The fuel pump doesn't fire up if the ecu is not getting a signal from the crank sensor.

hth.

Taylor.

Crank position sensor picks up from the big toothed wheel behind the crank pulleys. Sensor is on the right hand side of the engine, held close to the wheel by a little alloy bracket.
True that a faulty CPS will cause the fuel pump relay not to be triggered, but you should have bypassed the fuel pump relay (link pins 30 and 87) by this stage in the fault finding anyway.
If CPS is faulty it still won't start though, because there won't be any sparks.

Post Sun Mar 12, 2006 10:18 pm

yes mate by-passed that, where is the ECU located so i can check the connections ???

Post Mon Mar 13, 2006 1:10 pm

Did you know there is a fuseable link that comes directly off off the battery terminal with a thin black wire. It is buried under the plastic trim and is wrapped in sticky black tape. Mine corroded through because I had a leaky boot. Took me 5 days to find it.

Hope this helps.

Peter

Post Mon Mar 13, 2006 3:08 pm

Cheers matey, where is the fuse on that then ??

Got a tow hook now, so hopefully get it home this evening, am off work tommorow, so see what i can do..... AGAIN

Post Mon Mar 13, 2006 3:20 pm

Follow the thin black wire off the battery in the boot. It will dissappear under the trim with the big thick battery wire. There is a nut holding the trim and wires down out of the way. Undo this and pull out the big wire. The thin one will be wrapped around it with black tape. You will find it contains an inline fuseable link which protects the pump from overload. I think it was about Ãƒ”šÃ‚£7 from BMW but I ended up putting a large HIFI fuse holder and fuse in . THe ones they use for show cars with big stereos. You can get them from Maplins. Half the money and you can screw them in with terminals rather than soldering the BMW one in. Much easier.

Hope it solves the problem.

Peter

Post Mon Mar 13, 2006 3:30 pm

Battery in the boot ??

Post Mon Mar 13, 2006 4:24 pm

My 325 has the battery in the boot. Your car may not have but the principal should be the same. You should have a feed coming off your battery terminal for the fuel pump? I presume the fuel pump is in tank under the rear seat? Follow the feed lead back from the pump or down from the battery. You should somewhere along that lead have a fuseable link. In my experience there is not a fuse for it in the fuse box. It's a circuit like every other and must have a fuse in there somewhere. If the link is the same as mine then it's about 50mm long and will bulge in the loom if your wire goes into a loom. It is quite big so if it is there you should find it. It will probably be covered in plastic and wound with tape.

Peter

Post Mon Mar 13, 2006 5:02 pm

I don't have a clue what peterjk is on about but on ALL E30's the fuel pump fuse is number 11 IN the fuse box, regardless of where the battery is.
Whitterz
Did you do as Brian surgested and fit a bulb in place of the fuel pump to check for a constant voltage ?

Post Mon Mar 13, 2006 5:05 pm

Just shows you that you can learn something everyday. There is a fuseable link but obviously not too many know about it. You can buy them at the local BMW agent.

Post Mon Mar 13, 2006 5:07 pm

Havent been able to get it home yet

Post Mon Mar 13, 2006 5:11 pm

It took me 5 days to locate that fuse. It does not show in the manual. It is so buried away I was amazed because it was all bound up in plastic and tape. On mine that was the problem and it was damn difficult to solve because no one told me it was there. It was only when I looked on the parts catalogue I saw it. Bingo.

Peter

Post Mon Mar 13, 2006 10:51 pm

Thanks for the info guys

Post Tue Mar 14, 2006 1:13 pm

Right then guys went down the car today, replaced the fuel relay, there is power getting to the pump, but it isnt spinning up, or sucking thru....

i wired it to the battery and its doing the same, Just clicking......

any ideas

Post Tue Mar 14, 2006 1:26 pm

I know if the Idle control Valve fails it sends a signal to the Ecu . The ecu cuts the fuel I think?

Anyone?

Post Tue Mar 14, 2006 2:02 pm

this is even through direct wiring tho pal

Post Tue Mar 14, 2006 3:24 pm

Does it feed fuel through the system ?

Just because you can't hear it i wouldn't condem it just yet, Pull the bottom hose off the fuel rail and see if it is pumping petrol.
If not, THEN get a NEW one. Not another second hand one.

Post Tue Mar 14, 2006 4:37 pm

I know if the Idle control Valve fails it sends a signal to the Ecu . The ecu cuts the fuel I think?

you can disconnect the icv and still run????

Post Tue Mar 14, 2006 5:29 pm

Yes but if it has failed and is connected it can cause this fault

Post Tue Mar 14, 2006 8:05 pm

peterjk wrote:Yes but if it has failed and is connected it can cause this fault

not very convinced of what you say especially when you say a 316 has bat in boot!!!!!

first step as suggested is to confirm supply to fuel pump before lashing out.

Post Tue Mar 14, 2006 8:46 pm

gcorky wrote:I know if the Idle control Valve fails it sends a signal to the Ecu . The ecu cuts the fuel I think?

you can disconnect the icv and still run????

Engine will run normally with the ICV electrically disconnected, or physically removed and the hoses blocked. Just won't idle and will stall if you release the throttle.

Post Wed Mar 15, 2006 11:32 am

What will suggest a blocked fuel pump ???

Post Wed Mar 15, 2006 8:11 pm

Pull the bl**dy fuel supply hose off the fuel rail, power the pump up by jumping 30 and 87 of the relay and see if the damned things pumps!!!!
If it does then the pump is probably not the problem. If it doesn't, check for power at the pump terminals - with a 12V21W lamp NOT a meter.
If there's power there, then the pump is dead, if there's not, find out why.

Post Wed Mar 15, 2006 9:50 pm

ive fuckin checked it with a direct 12v supply if ud ready the fuckin post