[hegg]

So I just swapped out my fuel pump via the tank-dropping method. This means that I pulled off the shear panel and in doing so I noticed one of those bolts had a wire attached to it (a bolt on the left of the car). Figured it's just a ground wire, no big deal, just remember to hook it up later.

Well apparently the other end was not screwed into anything so I must have already unhooked it from somewhere. I found the wire laying on the floor a bit later (after moving the tank around, so it jarred it loose). I can't see anywhere within about the length of the wire and in areas that I've been working where it might connect.

It's a fairly short wire - maybe about 12 inches?

On a second note, after I got the new fuel pump in (following this excellent writeup: BOEFabrication.com | Beyond Original Equipment) I hooked the battery back up and turned the key but didn't get any pump sound. The fuel indicator also reads completely empty.

Seems to me that the mysterious wire could be the ground wire for the fuel pump, especially seeing that I can't see that the fuel tank is grounded anywhere. All of the mounting hardware is insulated from the tank. The fuel pump assembly had the ground wire connected to a flat piece which looks like it was intended to touch the tank opening for ground.

Anyone have any ideas? I'm the world's biggest moron when it comes to electrical, and Lotuses make it even harder since they're all plastic anyway!

Thanks in advance!

 

[hegg]

Oh, and regarding the fuel pump not pumping, the rest of the car is pretty much torn apart since I'm undergoing an engine rebuild. The potential for something being unhooked is pretty high, but in my very limited understanding of electricity, it seems like the fuel pump should still be turning on when the ignition comes on, right?

 

[kestrel74]

Don't ya just HATE when you have parts left over !!!!!!:huh:

 

[kmt63]

i think that is the engine to chassis ground.you most likely took the one end off when you removed the engine.then the other end when you pulled your tank.

 

[SirLotus]

Can't tell from the photo, but if this is a large gauge wire then maybe it is the ground from the tank to the chassis.
Michael

 

[charliex]

post the part number, if its A120M0030H/A120M0017F its the earth lead for the fuel tank.

most of the chassis earths are braided cables.

 

[hegg]

post the part number, if its A120M0030H/A120M0017F its the earth lead for the fuel tank.

most of the chassis earths are braided cables.

I'm almost certain that it's that part number (I can even make out the A12...00..H from that horrid iPhone picture). I've seen the braided chassis cables elsewhere - definitely not that.

So where does the other end connect? It doesn't look long enough to reach up top, but if it did, was it just connected to the retaining ring around the fuel pump? That's the only place with bolts I can think of that would touch the tank...

Thanks!

 

[darkSol]

So where does the other end connect? It doesn't look long enough to reach up top, but if it did, was it just connected to the retaining ring around the fuel pump? That's the only place with bolts I can think of that would touch the tank...

That's exactly where it goes... 10 o'clock position... right under the nut.

Upside down picture here - you can see it in the bottom right hand corner here:

 

[hegg]

That's exactly where it goes... 10 o'clock position... right under the nut.

Upside down picture here - you can see it in the bottom right hand corner here:

Oh!! Right there! The corner I can't see!

Now it all makes sense. I'm positive that's what it is. Thanks!

btw charliex, I just got my ECU back from you for VFII, thanks! I just saw in your signature that you do M100 tuning too - what kind of stuff? (I'm sure the answer is "anything".) I also had a few questions about what can be done with the Elise ECU. How's the best way to contact you? I don't want to waste your time and I'm sure you get about a million PMs a day...

 

[charliex]

easiest way is to call me 818 404 2395, the the link in my sig contains a lot of info about what i can do with them.

i guess didn't really word the sig correctly, i have an m100, and i can tune those ecu's. But i don't, instead leavng it upto MountainChips/ElanScanMan on lotuselancentral.com

cheers

 

[hegg]

Ok, I gotcha. I have the Everest from ESM in my M100 already and it's awesome, but I wonder if having a non-stock exhaust (damn thing rusted out) would necessitate a better tune sometimes.

As far as the Elise goes, it's just a silly question - can you display the current MPG on the digital dash readout area? (obviously it'd have to replace something else) I tried doing something like that with my Elan by taking the current speed, rpms, and injector duty cycle and applying some maths to it, but I was really just tinkering. The digital display on the Elise cluster always intrigued me to do it again though.

 

[charliex]

Cool, yeah i have one too, never used it since i ended up with a bigger impellor and lots more boost, so i just went with a rising rate.

You can display estimated MPG on the 08's+, but not previous cars without some significant mods, or a secondary display. then you might as well use one of the devices that do that.

For the significant mods part, its reprogram the freescale chip in the cluster, then add in the ECU an extra CAN message that tells it what the MAF/fuelling is.

the Injector DC calculation in the ecu isn't that great, so its better to roll your own.

 

[hegg]

Ok, thanks for the great answer. Sounds kinda like not worth it - it's just more for fun than anything. Getting 34 mpg (lifetime average) on the Elise now, was just curious how the SC will affect it and then I can alter my driving style by watching "live" mpg.

Wish tuning my twin Strombergs was as "easy" as flashing a chip. I hate carburetors sometimes...

 

[charliex]

yeah its a fair bit of work. just change that 34 to 'a lot' when its on boost/WOT, otherwise its not a lot different, depending on who's tune, which SC you're using etc.

 

[hegg]

All is well again - thanks everyone for your help. A few notes for further posterity...

(1) the fuel pump connector ground runs through the ECU somehow, so the fuel pump will not turn on without the ECU plugged in

(2) a fuel rail that's just laying out can easily and quickly have its injectors shot out (along with a large amount of fuel) from the pressure that the fuel pump can provide