M10 Main Relay???

[1990e30coupe]

Hello Rev,
I have a 1985 318i and I am not getting power to the fuel pumps. I Found that I had No Power to the fuse that activates the key on power at the main relay (fixed). I am curious to know if there is cranking power at the main relay that sends power to the pumps. When I turn the key on I have 3 positive powered wires at the main relay; therefore, does that mean I am back feeding power somewhere, or is there supposed to be three hots before cranking?

I am also wondering if someone has a reference to the fuel pump wiring as I find nothing in the Bently unless I'm looking past it (probably)? Can someone provide a link to the pinout of the main relay or where it would be at in the Bently?

I know there is cranking power that comes from somewhere, just not exactly if it comes from the main relay or the ignition?

All Grounds have been checked and are intact. The Bently doesn't really cover this fuel system well as far as a specific fuel wiring diagram.

Any ideas or help would be greatly appreciated as I have lost the path and not sure where to go from here.

Thanks.

[glnr13]

you checked the fuel pump relay beside the main relay?

[1990e30coupe]

you checked the fuel pump relay beside the main relay?

There is no fuel pump relay for this car, The main relay is for the fuel pump. It is a 1985 318I M10 (hince i posted under the M10 forum). Why does everyone on here respond without knowing what the hell they are talking about? I been an avid BMW enthusiast for years now and know a decent amount, but for some reason the little shit I get stumped on and turn to this forum I get mislead. Stop posting if you don't know!

[1990e30coupe]

Can anyone tell me how this motor reads engine speed. There is no crank position sensor, Nothing on the bell housing that reads the flywheel that I noticed unless I missed it ( which is very possible). I can't find it under ignition in the Bently as it just explains sensors for certain years all pertaining to 325e and 325i cars. Yet the main relay says it gets a engine speed signal from somewhere?

This is the first M10 I have delt with out of the 5 E30s I have owned and 2 E34s; therefore, somethings I am getting stumped on this fuel system.

[glnr13]

I had an m10 in my car initially and it did have fuel pump relay, right beside the main relay. 84 318i, US 6/83 build.

https://www.r3vlimited.com/board/for...28#post5833628

it's the little square shaped relay.

There is no fuel pump relay for this car, The main relay is for the fuel pump. It is a 1985 318I M10 (hince i posted under the M10 forum). Why does everyone on here respond without knowing what the hell they are talking about? I been an avid BMW enthusiast for years now and know a decent amount, but for some reason the little shit I get stumped on and turn to this forum I get mislead. Stop posting if you don't know!

you know, I get it. you're frustrated and trying to find a solution. here i am trying to offer some help and you wanna go and say i don't know what i'm talking about. cool. good luck on your journey.

[Jaxx_]

glnr13 is right, I would look at the fuel pump relay. Looks like confirming ground on pin 31 and grounding 1 should turn the fuel pump on. Obviously you want 12V at pin 87. Diagram below

What diagnosis have you already gone through?

[1990e30coupe]

I had an m10 in my car initially and it did have fuel pump relay, right beside the main relay. 84 318i, US 6/83 build.

https://www.r3vlimited.com/board/for...28#post5833628

it's the little square shaped relay.




you know, I get it. you're frustrated and trying to find a solution. here i am trying to offer some help and you wanna go and say i don't know what i'm talking about. cool. good luck on your journey.

I have a vacuum advance relay next to the main, and an o2 relay next to that. So the three relays under the hood go main relay, vacuum advance, and O2 for my car; therefore, no fuel relay next to main. Sorry but what your saying is that the Bentley is wrong! They are all tall large square relays man.

[1990e30coupe]

Glnr13,
Did you even read the post you sent me a link for cause even it says the main is the fuel pump relay.

[Sunnyledge]

Fuel pump relay for E30 M10 per factory BMW repair manual.

[1990e30coupe]

Have a broken wire, got it figured out, and yes Sunnyledge you got it right I already knew the position of the relay I was working with. You can tell the other two above that the fuel pump relay is not in the middle as your evidence shows. If you go to the one next to the fuel pump relay it says idle speed. The Bently calls it an vacuum advance relay in the middle. Now my 87 325 has a fuel pump relay in the middle next to the main, but not on this 85 318i. I appreciate the help locating what I already knew and it just fueled my drive to figure it out so thanks in that respect.

However, I should have been more clear on stating fuel pump relay and not saying main relay so sorry for the confusion on here.