Engine stops in reverse gear

[Bali]

Hi,

The following strange thing happens with my 2.0 IE nowadays: when I put it into reverse gear, the engine stops, and it seems that it runs out of fuel.
I think it will be an electrical issue around the fuel pump's relay and the reverse switch/lights (?), but if anyone has experienced similar - please let me know what should I check first.

Thank you,
Balázs

[Gregory Smith]

I would suspect the fuel pump ground. It's one of the many ring terminals at one of the taillight studs, a common problem. What's probably happening is the fuel pump is grounding through the reverse light ground, and when the light is lit, the fuel pump loses it's ground, or enough of it to stop the pump.

It's usually a good idea to clean/recrimp/solder the terminals and also clean the stud and sheet metal there. Over time the stud can get hot from the current and resistance and pull out or otherwise melt the housing, not pretty.

When I had my Zagato, I put new separate grounds on each light and attached them separately to the sheet metal around the tail light. Certainly no borrowed ground issues after that.

[SubGothius]

Sounds about right to me. When I first got my Zag, I had similar problems starting it when any other electrical items were in use, sometimes the reverse lights but particularly the HVAC fan.

Had a devil of a time figuring that one out, purely by chance as I was stranded (yet again for the umpteenth time) in a parking lot, cranking and cranking to no avail; after some time of this and fiddling underhood, I'd decided to conserve battery charge so shut off all electrical accessories, after which the fuel pump sound promptly settled from a loud buzz into the low purr that I'd learned to recognize as "ready to start".

This was with what I now realize was a marginal, on-the-way-out cubed-style electric fuel pump, which was never very effective to begin with and was apparently allowing fuel to drain back towards the tank while the car was off, so it was necessary to leave the low-oil-pressure light sender unplugged to allow running the pump for several seconds before cranking the starter. ::)

At any rate, make sure your fuel pump leads (esp. the ground) are perfectly sound, as well as those for the reverse lamps. It could be that the reverse lamp wiring alone has gone so dodgy as to soak enough current that the pump starves for adequate power.

[Jim Keller]

I'm with them! gotta be a lose ground at the tail lights, when you stick it in reverse the amperage pull with the backup lights on is taking all the power/grounding away from the pump, they ground at the same place on a couple tail light studs in the trunk. Take them off, clean them very good and re-install so they are tight, grease them so they do not coorode again

[Bali]

Hi,

Thank you for your help!
I have checked it, cleaned the connection - engine still stops a few seconds after putting it into rever gear... :(

I have disconnected both taillights - not help.
At the end I removed all the grounds above that taillight - the engine (fuel pump) runs fine without that.

What do you think, can the reverse switch be the problem? Where is it located?

Thanks,
Balázs

[SubGothius]

If you disconnected all the grounds at the taillight, and the fuel pump still runs fine, then the fuel pump must be gounded somewhere else... ??? This might be time to trace the pump's ground wire back to wherever it's actually attached to the body, since apparently at some point -- unless I misunderstand you -- someone rewired the pump and improvised their own ground terminal in a non-standard location.

I just discovered this myself when replacing my own fuel pump recently. Apparently a PO wasn't sure whether the ground wire they found dangling was supposed to attach to the pump, or supposed to attach to the body to provide a ground for something at the wire's other end, so they attached that "mystery ground wire", plus a homemade ground wire for the pump, to an improvised ground terminal screwed into the underbody of the car, where it would be nice and vulnerable to corrosive and contaminative influences... ::)

[Jim Keller]

The reverse light switch is on top of the tranny under the battery tray area, you should be able to un-plug that and see if it has anything to do with the problem, it is the only thing on the tranny with wires going to it ;) maybe it is shorted??? Also, check the fuses in the box, make sure the fuses and the terminals are all clean and snug, could be a problem there basically caused by the same amp pull senerio with the grounds, only on the power side and most likely, at the fuse box, is yours in good condition WITH a cover with no cracks or holes? if it is open to the eliments with even just an un-sealed crack in the plastic, they can coorode fast on you. I think the fuel pump fuse is #13..... :-\ or #16, I cant' remember for sure ???

[Bali]

Hi,

It works!
I have checked that switch, and cleaned its connector. Also checked it with a multimeter - it is OK.
Then cleaned a little bit the fuses (actually they are in quite a good condition).

After these the car behaves well, reverse lights work, engine does not stop.

Now I am not sure what was the real cause of the problem - the fuse or something around the reverse switch.
I have recently changed the clutch bowden - maybe I dislocated something during that maneuvre (I did not know the reverse switch is somewhere there - actually it is at a quite tricky place). But right after the bowden change there was no such problem...

I really think that re-wiring the whole car should solve 50% of my problems (rust: 40%, other: 10%) :)


So thanks again for your help.
Balázs

[Jim Keller]

Yea! :D
It is always hard to help over the internet! LOL glad we coul help! ;)