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Fuel pump delete?

September 01, 2012 05:29PM
Hey guys, quick question;

Has anyone heard about the fuel pump delete for E30s with the duel pumps?
I've read about it but can't find the procedure online, anyone know?

My "main" pump isn't receiving power while my sender pump is reading low on volts, despite replacing it, so i suspect wiring faults.
And so I figured I'd reduce my pump number to one.
September 01, 2012 10:13PM
Is the high pressure pump external to the tank? If the "sender" pump is in the tank, the one outside will cavitate and not provide the pressure at full flow that is needed.

Bob in Everett
September 02, 2012 02:41AM
Bob is right, it would involve more than simply removing the transfer pump.
The way I would approach the task is to replace the in tank pump with the high pressure pump from one of the later models that only had the one pump, the high pressure pump in the tank.
Thus doing away with the transfer pump and moving the high pressure pump into the tank.
This would be the simpliest way to do it, of course the first prize is to investigate why you have no/low voltage.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
September 02, 2012 10:11PM
Are the pumps (the old style transfer pump in the tank and the new style high pressure pump on later models ) the same shape for direct bolt in?

alan
September 03, 2012 04:35PM
Al. it looks like they may just be the same, I doubt BMW would re-invent the wheel.
Looking at this diagram for the '84 325 with two pumps, the tank and the "pre supply" pump as they call it, look identical to the pump in my '91 318i that only has the one pump.



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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
September 03, 2012 07:24PM
Might want to check the part numbers.... The thing with the second pump might be getting all the usable fuel out of the tank.

Bob in Everett
rkj
September 03, 2012 10:05PM
I think there are pressure differences too, between the two systems. The older eta runs on less.

Rick
September 03, 2012 11:39PM
Bob you are right of course, before spending coin, you would want to check the part numbers, or at least take the old one with as a sample to check the fitting and length.
Rick,.I reckon the pressure would not be too much of a problem, they all run around the 3 bar mark, give or take half a bar, therefore it would be logical that the pump would supply more pressure than that and the final injector pressure is controlled by the fuel pressure regulator, keeping fuel pressure at a steady value above ambient pressure, and the fuel pressure regulator would be suited to that motor anyway, or am I missing something?

----------------------------------------------------------------------------------------------------------------------------------
E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
September 05, 2012 12:49AM
Quote
Flyboy
Bob is right, it would involve more than simply removing the transfer pump.
The way I would approach the task is to replace the in tank pump with the high pressure pump from one of the later models that only had the one pump, the high pressure pump in the tank.
Thus doing away with the transfer pump and moving the high pressure pump into the tank.
This would be the simpliest way to do it, of course the first prize is to investigate why you have no/low voltage.

Ahh, I understand this concept, but I put in a newer aftermarket "transfer" pump from my friend's car, though this is no great difference, unless it's newer. Should the newer single pumps have weird net things on them? This one does.

As for the conversion, I've heard you can simply take out the underside pump, connect the fuel lines in its stead, and run it that way but that just begs the question; "WTF BMW, WHY YOU HAVE 2 FUEL PUMPS!?" :wall::doh:

Still welcome to any input, I haven't been up to work on her in a bit. Haven't had the parts to figure anything out, or the ride for that matter.
If a main pump swap doesn't work, ima be jumpin around, stomping my feet like an angry leprechaun.
BARG. :furious:
September 05, 2012 01:30PM
Whatever the reason, the engineers designed the system such that the low pressure pump feeds the high pressure booster pump downstream of the tank. Most cars have a single pump in the tank which does it all. As was posted above, BMW went to the single pump down the road.

The mesh stuff is probably to keep the big chunks in the tank and out of the pump and rest of the fuel system.

alan
September 05, 2012 02:54PM
Yep, the mesh bag on the end is to keep any gunk out of the pump, mine has it as well, sounds like the right pump.
I am still inclined to have a niggling feeling about the low voltage, I really think tracing and rectifying that problem first is of more importance, once that is sorted, install away to your hearts content.

----------------------------------------------------------------------------------------------------------------------------------
E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
September 05, 2012 05:48PM
I think the fuel pump runs off of the relay so you should be getting 12.0V. Not sure of what the current rating is or if there is a fuse as well on the fuel pump.

alan
September 05, 2012 10:32PM
Al, the pump is indeed 12v, so he should be getting 12v at the pump wires under the back seat, you don't even want to know how I know that...........:rolleyes:

Bam, you need 12v there, any less and pump performance will be degraded and you are not going to get the required pressure, no matter what pump you put in the hole.
Try putting 9v to your starter motor and see how well it spins the engine over...or not, same concept.

----------------------------------------------------------------------------------------------------------------------------------
E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.



Edited 1 time(s). Last edit at 09/05/2012 10:36PM by Flyboy.
September 10, 2012 04:40PM
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


rkj
September 10, 2012 09:53PM
Quote
bam_loves_his_bmw_325i
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


Give up on the single pump idea?
September 11, 2012 05:08AM
Quote
bam_loves_his_bmw_325i
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


Your car grew teeth! eye popping smiley
September 11, 2012 09:02AM
Quote
Jose Pinto
Quote
bam_loves_his_bmw_325i
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


Your car grew teeth! eye popping smiley

And horns :eyes:
September 11, 2012 03:43PM
Quote
rkj
Quote
bam_loves_his_bmw_325i
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


Give up on the single pump idea?

Yeah, it seems plausible but I'm too frustrated and/or lazy to see if i can make it happen haha. smileys with beer
September 11, 2012 03:46PM
Quote
Jose Pinto
Quote
bam_loves_his_bmw_325i
Got a new underside pump put in, was a nightmare to get those hose clamps off.
She lives again!

Thanks guys.


Your car grew teeth! eye popping smiley

That's my shark, watch out; she bites. :cool:
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