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View Full Version : so im about to change my fuel pump..and


W2WDETAILING
04-21-2009, 09:38 AM
i go to my car look at the old fuel pump and i get very confused then i realize the po put the early e30 pump in and blocked off the return line... i knew it wasnt possible because i allready replaced the return line

but hey if you only have access to an early pump i guess this works too

InfiniteDice
04-21-2009, 11:09 AM
Some of the earlier in-tank pumps are transfer pumps only. But you probably know that.

The Sly
04-22-2009, 12:20 AM
Some of the earlier in-tank pumps are transfer pumps only. But you probably know that.

Well E30's up to end of 1987 had 2 pumps and 88 and up have only one in tank pump.

But this is crazy, this is a 1990 e30, so one pump but it needs a return line or else the fuel pressure with go high since there is no return:confused::confused::confused:

W2WDETAILING
04-22-2009, 01:08 AM
Well E30's up to end of 1987 had 2 pumps and 88 and up have only one in tank pump.

But this is crazy, this is a 1990 e30, so one pump but it needs a return line or else the fuel pressure with go high since there is no return:confused::confused::confused:


yeah ok you lost me there ofcourse it needs a return line but it goes directly into the tank instead of going into the top of the pump if that helps explain it. but the po used a 88/89 pump im guessing and blocked the return because it has a return in the tank.

richie_s999
04-22-2009, 01:41 AM
so is it running good with the new pump???

W2WDETAILING
04-22-2009, 01:55 AM
so is it running good with the new pump???

yeah and it fired right up before i had a bit of lag when i would give it gas now it seems pretty percise. my old pump had a funny fitting sometimes the car wouldnt start unless i jiggle the connection thanks for the pump riche

richie_s999
04-22-2009, 01:58 AM
yeah and it fired right up before i had a bit of lag when i would give it gas now it seems pretty percise. my old pump had a funny fitting sometimes the car wouldnt start unless i jiggle the connection thanks for the pump riche

*th-up*

The Sly
04-22-2009, 03:02 AM
So your saying that you replaced the fuel pump and it is working great!

My question is : Did you connect the return line from the fuel rail back into that hose...

See the way it works, this is a in tank high pressure pump which pumps fuel to the fuel rail and the fuel pressure regulator on that rail will give you a constant ~43psi and what ever is too much coming from the pump, will return to the gas tank.
A fuel injection pump will certainly give you alot more than the needed fuel in the fuel rail for the injectors and that is why you have a "FPR" fuel pressure regulator.

Now i sure would like to see what you got at the end of the fuel pressure regulator where the return fuel is suppose to go.

I guess at this time if the fuel pressure regulator is blocked, your running at the fuel pump maximum pressure.

Anyway you should investigate further into this, specially if you have replaced the pump...

Sly


yeah and it fired right up before i had a bit of lag when i would give it gas now it seems pretty percise. my old pump had a funny fitting sometimes the car wouldnt start unless i jiggle the connection thanks for the pump riche

echo
04-22-2009, 03:13 AM
READ the thread - he has a return - it goes back to the tank, not the pump. It was the wrong pump for year of car and someone has simply blocked off the return as it is not needed at the pump - it goes directly back to the tank

The Sly
04-22-2009, 03:50 AM
OH GREAT AND THANK FOR PUTTING IT IN BIG LETTERS ECHO
you woke me up*shiner*

I completely MISSED that part of the thread...I was so trying to figure out how this car could still run without a return line...that i went right past that line.

W2WDETAILING
04-22-2009, 09:23 AM
OH GREAT AND THANK FOR PUTTING IT IN BIG LETTERS ECHO
you woke me up*shiner*

I completely MISSED that part of the thread...I was so trying to figure out how this car could still run without a return line...that i went right past that line.

ahah well now im awake too... ofcourse i have a return line

The Sly
04-22-2009, 01:34 PM
yea
Weird that they had a line going to the tank instead of using the right return location...no matter which pump you use,transfer or high pressure pump, early or late pump, they all look the same in there and the tube that is blocked off is for fuel return to the tank....
but as long as your ride is running like it should, that's what counts.
*th-up**th-up**th-up*

W2WDETAILING
04-22-2009, 02:28 PM
yea
Weird that they had a line going to the tank instead of using the right return location...no matter which pump you use,transfer or high pressure pump, early or late pump, they all look the same in there and the tube that is blocked off is for fuel return to the tank....
but as long as your ride is running like it should, that's what counts.
*th-up**th-up**th-up*

ok wow you lost me ..i have a feeling your still confused. here let me show you a picture of the new"er" pump
ok the first picture is the early model pump in a late model e30

the second picture the late model pump is in the late model e30 the way it should be

The Sly
04-22-2009, 06:31 PM
He He don't mind me.....
This is the perfect picture for this model....man that gas tank looks pretty clean. No rust around the pump Unit whatsoever.*th-up*
Has it been replaced?

W2WDETAILING
04-22-2009, 07:08 PM
He He don't mind me.....
This is the perfect picture for this model....man that gas tank looks pretty clean. No rust around the pump Unit whatsoever.*th-up*
Has it been replaced?

as far as i know thats the original gas tank.

echo
04-23-2009, 04:11 AM
lol, sorry wasn't meaning to sound like an asshole, but reading it back that's what I am.

Do you guys have trouble with rusting tanks?? Maybe something to do with salt on the road with cold weather??? Rusty tanks are fairly rare here. That tank looks like it has rust protection on it - none of the ones over here do, and that is pretty rough-looking compared to almost all the ones I've seen.

BigD
04-23-2009, 09:01 AM
You'll need to do this again with the proper pump or you'll fry this one in no time (and I'm sure at WOT runs you'll be going lean). The in-tank pump of the early cars is only a transfer pump, it's not designed to be the sole provider of the spec fuel pressure.