Fuel Pump Replacement

Changing out my fuel pump because of a no-start situation from this thread:

http://www.e9coupe.com/forum/showthread.php?t=12475

My buddy and I did some hi-tech trouble shooting in the parking garage and determined there was no fuel flow. The consensus here is that it's the pump. Although my BMW buddy also cautioned the relay by the ECU energises both the fuel pump and the injection ECU. Well, no fuel=bad pump to me. We'll see. So I oredered a new one, should be here tomorrow. About $265 (my screaming deal, frequent buyer price) from the local dealer.

Had the poor thing towed home and pushed it into the shop. Long story short, I pulled the pump for replacement tomorrow.

A SPECIAL PSA HERE:

WEAR YOUR SAFETY GLASSES WHEN WORKING ON YOUR CAR! (Or anything else for that matter).

No problems happily, I just thought about them while laying under the car with dirt/grime and gasoline falling down on my head. Had my "cheaters" (reading glasses) on so was semi protected but not enough.

Anyway.....

This falls into the catagory of "you can't make this $hit up". Somebody around here has a sig line that goes something like "if you can make it more complicated, why not?" in German. Well, the fuel pump fits this description perfectly.

The pump and "expansion unit" are mounted with a three point rubber mount set up.


double ended rubber vibration mounts? Really?


So when you take off a nut and think you can now push the matching bolt thru to release the mount, it ain't happening.

I finally got enough of the nuts off to be able to release the pump/expansion tank off the bottom of the car.

Here's the pump on the bench. You can see the rubber mount in the upper right






Here's a shot of the clamp

So even though you now have the assembly out of the car, you still can't take it apart. You have to remove the fuel fitting and, even then, there is a pin you have to get by to remove the pump from the assembly bracket. You can see the pin between the fuel fitting and the plug, right next to the bracket. You can see one of the double ended rubber mounts at the upper left.



Anyway, got it out, new pump on the way, but I really don't know how I'm going to get it back installed. I'll try to take some shots of what under the car. The stuff on Real OEM and what not don't do any justice.

Sure wish I had a lift!

To be continued......

hello bwana

Hey I don't know where Conroe TX is but I'm in Cedar Park/Austin and if you ever need to do a week-ends work with a lift and most of the "goodies" just send me a note. My e9 is lonely!

Peter C

Wine tour

Just north of Hootin'

We'll swing thru sometime this winter/spring on the way to the Hill Country Wine Tour!

Thanks for the offer!

What to do now?

Got a new (superceded) pump from the dealer. But the nozzles are slightly different and so is the electrical connection. Both can be overcome. But the diameter is significantly smaller so I'd have to shim it with something like a piece of rubber.




Differences in diameter



In case you wondered, here's what it looks like with the top off. I think the fuel flows from the tank, thru the motor for cooling, then out to the engine (big suction, small discharge)



So, do I

1) Modify the new pump to fit?

2) Do I try to fix the old pump?

3) Try to find an new/old pump to replace the bad pump?

Suggestions?

A thought

I think I would bring both new and old and the bracket down to a muffler shop and have them expand a piece of pipe to fit snugly around the new pump and then clamp it into the old (cleaned up and freshly repainted-I'm sure) bracket. Then it would look close to "factory" and since it's under the car no one would really see it. Also, since below you mentioned how much of a PIA it is to take off- at least you would have a spankin' new pump- hopefully good for another 40 years

I think reliability in this case trumps all - just my 2 cents as I had my electric pump go out on a 740il with both 2 year olds in the car and allot of traffic- quite scarry!

Looks like a good project though!

Maybe use some radiator hose cut to fit - it would provide the tightness as well as be an added sound/vibration insulator

Well, if it were not for Ace hardware, old cars would never bee restored. Went to Lowes and Oriley with no luck looking for some sheet rubber, the guy at Ace said "sure" and took me right to a package of two different thicknesses of rubber sheet. Fit the pump right into the old bracket.

My next challenge is figuring out the polarity of the plug coming from the car. Both wires appear to be white but the wiring diagram seems to indicate one brown (ground?) and some other color. The new plug has a different wiring set up but I've made some pig tails that will with tdifferent ends that will work. So how can I figure out which is hot and which is ground? I've put a volt meter on both, turnend on the cat, heard the relay click, but no voltage on either plug.

Suggestions?

Edit: Found the ground side! Hopefully the lack of voltage on the first test doesn't mean something else

Run a jumper or pin out continuity on the wire to ground and to the fuel relay. You did test the fuel relay before ordering the pump right? )

sfdon said:

Run a jumper or pin out continuity on the wire to ground and to the fuel relay. You did test the fuel relay before ordering the pump right? )

Click to expand...

I didn't check voltage output, I took the seat out and could hear and feel the relay pickup. Not real scientific but it seemed OK. Replacing a 40 YO fuel pump probably isn't a bad idea anyway.

verify the relay is good- buy a new one and keep the old in the glove box as a spare.

Success!

New pump in and no leaks. I figured out you can remove the wheel and reach in in most cases instead of having to crawl under the car.

Thanks for the suggestions!

congratulations