1998 318i Fuel Pump Troubleshooting

[dsrtftr]

Hello - this is my first post. I hope someone will be able to provide some wisdom. Thank you in advance.

This is a car that was running, but was parked for 6 months, and now we have a no-start situation. Initial diagnostics show no fuel pressure. Fuel pump works when connected directly to 12 volts. There is no voltage at the wiring harness leading to fuel pump. So I started poking around the relay.

[IMG]https://photos.app.*******/VEgoSvvL8tqqzV8D6[/IMG]



Questions:
1. Is it correct that the relay with marks (A, B) is the correct relay?
2. Is it correct that the fuse marked C is the correct fuse?
3. Is it correct that A should be hot; and shorting A to B should make C hot?

What I am seeing confuses me:
1. A is hot.
2. There is continuity between B and C.
3. There is continuity between C and the hot lead at the fuel pump.
4. When I short A to B, a. It sounds like some kind of a blower starts near the intake side of the engine. b. There is not 12 volts at C. c. Fuel pump does not kick in.

What I expect is that shorting A to B would cause 12 volts to appear at the fuse, which would make the fuel pump kick in. Does anyone have any ideas what I'm doing wrong, or alternately, what might explain what I'm seeing?

Thank you for your help!!!

(I don't know if the image is visible, but remove spaces from url below to see image in google photos)
https:// photos. app. goo. gl/ VEgoSvvL8tqqzV8D6

[MarcoZandrini]

Go to www.newtis.info for wiring diagrams. It sounds like you’re messing with the wrong relay.

You did check the fuse panel, didn’t you? Where was the car stored? Rodents like to eat wiring for some reason.

[dsrtftr]

Go to www.newtis.info for wiring diagrams. It sounds like you’re messing with the wrong relay.

You did check the fuse panel, didn’t you? Where was the car stored? Rodents like to eat wiring for some reason.

Thanks for the resource you provided. The link: https://www.newtis.info/tisv2/a/en/e...e-line/4UGvs82 confirms that shorting those terminals in the relay should trigger the fuel pump.

I looked for rodents or chewed wired but did not see anything. i guess I'll need to look again more closely.

[bmwdirtracer]

Your links don't work for me at all, spaces removed or not.

Now, I've got to tell you that TIS really screwed the pooch on this one. Trouble is, TIS is too new, and just threw all the E36's into the same pile: WRONG ! (Actually, there are TWO mistakes: fuel pump relays do not use terminal 87b, either)

Go here, instead:

http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

These are the actual BMW factory ETM's which were used when your car was made. Follow along with me:

Click on M44 engine , in the left directory column.

Go to page 111 of the Adobe document. You will see K6301w, the fuel pump relay for your 318.
Note that there is NO terminal 87b shown, because the fuel pump relay works through terminal 87 to power the pump. Note that the wire at terminal 87 is green and violet. (We will use that to doublecheck, in a minute)

Now, in the left hand directory column, scroll down to "Component location chart". Click on this.

Scroll down the list until you come to page 299 of the adobe document, where you will find K6301w, your fuel pump relay.
Note that it says this is shown on page 7100.0 -19 - 1

Use the left column directory to click on Component location Views, which will bring you to BMW page 7100.0 (see the right margin of the page)
Scroll down 19 pages, to page 7100.0 - 19-

Now, look at View #1....uh oh...you're testing the wrong relay! The fuel pump relay on your car is in the middle slot.

But, let's double-check: There's a little black tab on the outside of the relay, which is a clip that holds it captive on the fusebox. Push that tab towards the relay (maybe away from it, I don't remember), while pulling up on the relay and it's plug.

Does this relay have a green and violet wire? That's the one that needs power. Terminal 30 of that relay should be hot all the time, jumper it to the green violet at terminal 87.

[dsrtftr]

Your links don't work for me at all, spaces removed or not.

Now, I've got to tell you that TIS really screwed the pooch on this one. Trouble is, TIS is too new, and just threw all the E36's into the same pile: WRONG ! (Actually, there are TWO mistakes: fuel pump relays do not use terminal 87b, either)

Go here, instead:

http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

These are the actual BMW factory ETM's which were used when your car was made. Follow along with me:

Click on M44 engine , in the left directory column.

Go to page 111 of the Adobe document. You will see K6301w, the fuel pump relay for your 318.
Note that there is NO terminal 87b shown, because the fuel pump relay works through terminal 87 to power the pump. Note that the wire at terminal 87 is green and violet. (We will use that to doublecheck, in a minute)

Now, in the left hand directory column, scroll down to "Component location chart". Click on this.

Scroll down the list until you come to page 299 of the adobe document, where you will find K6301w, your fuel pump relay.
Note that it says this is shown on page 7100.0 -19 - 1

Use the left column directory to click on Component location Views, which will bring you to BMW page 7100.0 (see the right margin of the page)
Scroll down 19 pages, to page 7100.0 - 19-

Now, look at View #1....uh oh...you're testing the wrong relay! The fuel pump relay on your car is in the middle slot.

But, let's double-check: There's a little black tab on the outside of the relay, which is a clip that holds it captive on the fusebox. Push that tab towards the relay (maybe away from it, I don't remember), while pulling up on the relay and it's plug.

Does this relay have a green and violet wire? That's the one that needs power. Terminal 30 of that relay should be hot all the time, jumper it to the green violet at terminal 87.

Really interesting information.... I'm away from the car until Thursday, but will trace things based on your insight then. You are correct - the large hot leads from the relay I was testing were red, not green-violet... I'll report back what I find. THANK you!

[dsrtftr]

Hi Chris - thank you very much for your reply. I'll look at the car later in the week based on your advice. The leads coming from the relay I was looking at were red - so that matches what you wrote. I'll update you with what I find. Thanks!!!

[bmwdirtracer]

Be VERY careful NOT to switch relays around, by the way. Some are safe, some will melt the wiring harness. (The SAP relay slot must ONLY ever see the correct relay).

In my experience, the fuel pump relay is rarely the culprit. I would recommend looking for spark, first. If you have spark, then you can worry about the fuel delivery. If you don't have spark, we look at why the computer is unhappy.

[dsrtftr]

I have no pressure at the fuel rail & when I spray starter fluid in the intake - it catches for a tiny bit... So at least I'll continue 'till I have pressure at the fuel rail. If that does not do it, will go from there.

[bmwdirtracer]

I highly recommend that you use brake cleaner, or MAF cleaner, and NOT starting fluid (ether). Ether is SO volatile that it can compression-ignite, like a diesel, even if there's no spark. It can also explode your intake manifold.

[dsrtftr]

Chris -

Just wanted to follow up. You were correct that the fuel pump relay I was testing was the wrong one. In my case, the relevant one was the #3 one (closest to the rear of the car). That said, you also were correct that this wasn't my problem. Long story short, flooded DME Dried it out and engine fired, though it has a rough idle still at this point... I shut things down, will move the car to my garage, and will take my time proceeding from here. Hopefully by Feb, will have something reliable for my 16 y/o daughter to drive Thank you for your detailed help. It got me on track!

jP