E30 Fuel Pumps

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Thaumaturge
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Thu Jan 10, 2019 12:14 am

Hi all. New member here and completely new to car mechanics. I've had an F reg 318i SORN for a long time in an underground garage and thought i'd do what work i could myself in getting it back on the road to learn something and cut costs. I bought a replacement fuel pump on ebay which the seller, having asked for my reg, assured me was the correct part. Too late now for a refund but the point is once i opened the tank i find i have the two-pipe setup and the new pump is single pipe. Can the actual pump part of the unit work in both versions or do i need to order a whole new unit?

thanks
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Brianmoooore
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Thu Jan 10, 2019 10:01 am

Assuming the new pump is of a similar design, the pump itself can be swapped over. The only difference between the two is that the second (fuel return) pipe is cut off at the top, capped off and only used as a support for the pump.
Your tank uses the returning fuel to prime a siphon system that transfers fuel from the RH side to the left.
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paultv
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Thu Jan 10, 2019 10:02 am

Have you got any part numbers? or a link to what you bought? and did you check your VIN on Realoem to see what your car should have?

Paul :-) and what Brian said!
4th May 1990 325i Convertible.

BMW E30 Cabriolet Best Mod Ever:

http://bmwe30cabriolet-wdm.blogspot.de/
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martauto
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Thu Jan 10, 2019 3:23 pm

I have no idea about this but the guys above are pretty darn good.lol

Welcome to Zone as well mate :beer: :beer:

Pics are most welcome .

Mart.
E30 316 Baur 1987 ( Legal again !)
E46 325 SE Cab 2004 (Undergoing serious top down time !)
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Thaumaturge
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Fri Jan 11, 2019 6:07 am

Thanks for he replies and welcomes :)


I'm attaching pics of the pump purchased. I didn't check it against realoem as it's completely new to me.


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As i say i'm new to car mechanics so not really understanding the explanation of differences between the pumps. If fuel is being combusted, why is it returning? And does the siphoning mean there are actually 2 tanks i need to drain?


Part number on the new pump reads

G4V18PC0328-04


Here's a link for the purchase/ad

https://www.ebay.co.uk/itm/NEW-Electric ... :rk:1:pf:0


So if i strip the pump portion of this i should be able to put it into the older unit?
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Brianmoooore
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Fri Jan 11, 2019 10:54 am

That pump looks like it can be transferred to your original frame.

Fuel is pumped from the tank by a pump that is capable of producing several bar of pressure. The fuel goes to the injector fuel rail , connected to the 'in' end of the injectors via a filter.
Also connected to the fuel rail is a pressure regulator, where the fuel in the rail acts against a spring loaded valve, allowing fuel to escape. The spring tension is such that the valve opens at 3 bar (for a 2.5 litre engine), so the pressure in the rail is stabilised at that pressure.
The fuel that 'escapes' from the regulator is fed back to the tank, where it enters via the second pipe on the pump on the smaller 55 litre tank, or via a pipe on the side of the tank in the case of the 62 litre tank, where it primes an internal siphon system.

Yes, on the 62 litre tank, there are effectively two tanks to drain, unless you keep the fuel pump running by 'hot wiring' it.
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Thaumaturge
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Fri Jan 11, 2019 11:41 pm

I see, thanks for the explanation. I'll pull the pump out and see what's what. On the offchance it isn't compatible do you think a benchside run through some degreaser would be good enough? The whole reason i'm doing these bits is the car has sat for a decade with stale fuel.
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Brianmoooore
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Fri Jan 11, 2019 11:58 pm

If the fuel in the tank predates when a small proportion of ethanol was added, then the pump my be savable. Ethanol absorbs water, and corrodes anything ferrous it comes into contact with.
It's possible to carefully bend back the crimp on the bottom of the pump, remove the black plastic base, free up the pump, then put the base back exactly where it was and bend the crimp back again.
Having said that, most original E30 pumps are a bit long in the tooth now, and either the commutator of the motor is nearly worn away, or the pump gears are worn and prone to jamming.
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Thaumaturge
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Sat Jan 12, 2019 12:21 am

Hmnn.. i did add a bit of fuel more recently when i tried to see if it would start so, if doable i'll try the swopover first. Finger's crossed! Draining fuel wise.. do i just need to remove that other panel on the LHS of back seat to get to the extra tank?
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Brianmoooore
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Sat Jan 12, 2019 10:00 am

Under the other panel you will find a second fuel level sender, required because the levels in the two tanks differ from each other. The second fuel sender fits into the tank in an identical way to the fuel pump.
P.S. Probably should have mentioned earlier that to remove the fuel pump, you have to remove the level sender fitted to it first, otherwise the assembly will not come out of the hole in the tank, and trying will damage the level sender's tube.
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Thaumaturge
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Mon Jan 14, 2019 2:49 am

Thanks again and no worries. I watched a few youtube videos of these being removed which showed the fuel level sender etc.
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Thaumaturge
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Tue Mar 26, 2019 2:49 pm

Bit slow here.. but i finally got around to pulling the pump and removing the old fuel/creosote. I'm charging the phone up to take some pictures that i'll add later but as it is the old housing, contacts etc look pretty corroded so i'lll be interested to see if you think they'll be worth salvaging. Also.. on opening the cover on the LHS i only saw the top of the tank and no access.. which remimnded me that the tank had been changed in a previous service so does this look like i have just the one tank although still the two pipe setup?

Also.. i wasn't able to remove the last little bit of fuel from what looks like a close fitting sump under the pump. Is that likely to cause a problem if left?
Lastly, now extracted i can hear the float in the sending tube sticking at the top. Should i replace that to or is there a way or cleaning it? Or is it ust the case hat once extracted it's actually too dry to float freely as it would in fuel?
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Thaumaturge
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Tue Mar 26, 2019 8:04 pm

Pics attached ... doesn.t look like itll'l work anyway as the bottoms are different.

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Brianmoooore
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Tue Mar 26, 2019 8:28 pm

Old pump's not pretty, but I've resurrected worse! Unsolder the wires and unhook the pump from the frame at the bottom with a bit of gentle pressure. Fuel outlet at the top is just pushed in and sealed with O rings, so just slides apart.
Get some releasing fluid up inside the pump, and connect it up to a 12 volt supply. Try correct polarity, and then reverse polarity alternately, and it may free up. If it refuses to work, it's possible to uncrimp the bottom of the pump and remove the black plastic disc (mark its position first). This gives you access to the rotor of the pump, so, if the motor is any good, you can definitely free it up. Carefully refit the base and crimp the aluminium.
Had to do this to the one that suffered ethanol damage.
It still looks like your new pump could be fitted to your existing frame with a bit of cutting work to the bottom plate. As long as it can't fall out it will work fine, and the O ring connector piece at the top can be replaced with a short piece of high pressure fuel hose and clips if necessary.
Make sure you solder the wires back on the pump the correct way around.
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Thaumaturge
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Tue Mar 26, 2019 8:43 pm

Thanks for all that. Another factor is that the old sock didn't come out with the pump and i can't see it in the tank. As you can see the fitting for the sock on the new pump is different. I would probably want a dremel or the like make the base on the old frame accept the new pump which i don't have. It's a shame there isn't a handy way to simply make the new pump accept the 2nd line again.. i.e. removing the capped off section and adding the lug but i suppose anything proper there would need welding which again i don't have.
All this being said i'll prob just sell the new pump and order the proper replacement. But this is all good knowledge if i ever service these again. What would you have recommended for releasing? Would thinners have been good enoug.. methylated spirit/isopropyl alcohol?

Also what about that second tank.. is it possible he swopped in something that works as a econdary tank but doesn't have access for me to drain.. or might i just have the larger tank under there?
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Brianmoooore
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Tue Mar 26, 2019 8:54 pm

OE tanks have a drain plug on the outside of tank, at the bottom, on the pump (RH) side. On a 55 litre tank you can drain nearly all the fuel through the drain, but on the bigger tank tens of litres with remain in the LH side, unless the pump is hotwired to transfer it to the RH side.
Lidl's sell a 'dremel' type tool from time to time for about £20, IIRC.
You've nothing to lose by trying to free up the old pump, so worth a try. WD40, Duck Oil, etc., is what I mean by releasing fluid.
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Thaumaturge
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Wed Mar 27, 2019 8:54 am

It's not really worth it as I don't have a sock that will fit it. All in all too much more expense and hassle now when i can resell this new one and for another £20 get a correct new replacement. That's a pain about the tank ..
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Thaumaturge
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Wed Mar 27, 2019 9:23 am

Are there any guides for hot wiring the pump to drain the lhs tank? It'd be worth getting the pump working if i can use it (sockless) to move the fuel over. I stripped it off and the bottom gasket completely crumbled away which i guess in the long term might allow fuel to get into the housing but maybe it'd be good enough for this task..
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Brianmoooore
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Wed Mar 27, 2019 10:14 am

Remove fuel pump relay (orange one under the bulkhead cover, next to fuse box, on 4 pots), identify pins 30 and 87 of the socket by looking at the numbers on the relay base, and link them together with a short piece of wire. Fuel pump will be powered continuously.
Note that if the pump is jammed, fuse 11 (7.5A) will be stressed and will eventually blow.
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Thaumaturge
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Wed Mar 27, 2019 10:53 am

Thanks again
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Thaumaturge
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Sat Mar 30, 2019 12:40 pm

I stripped the pump and ran 12v through it. It feels like the motor is running but no suction. How do you go about disassembling the housing the further inspect/clean?
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Brianmoooore
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Sat Mar 30, 2019 2:10 pm

If the motor's running (should take around 2A), then I can't really see how the pump can't be running. - it's just a simple gear pump. It has very little 'suction' - it's designed to be immersed in fuel.
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Thaumaturge
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Sat Mar 30, 2019 2:14 pm

I had the bottom immersed in thinner and ran it off my 6A charger. Although it activated nothing was coming out of the top pipe. Am i doing something wrong?
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Brianmoooore
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Sat Mar 30, 2019 7:18 pm

Electrical polarity correct?
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Thaumaturge
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Sat Mar 30, 2019 8:28 pm

I started with correct polarity then tried opposite. No change.
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Brianmoooore
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Sat Mar 30, 2019 9:34 pm

There's a non return valve built into the outlet of the pump which, I suppose, could conceivably be stuck shut.
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