nine9six

Constructing as the title says...

I am thinking the use of a fused, 12 gage wire, with blade connectores at each end.

So what amperage fuse should be utilized?

P.S. This is an emergency fuel pump operation jumper; and yes I do carry a spare DME relay.

Thanks in advance, gentlemen...

From the workshop manual...
"Pull DME relay (R53) off the Central Electrical
System and use a fuse-protected shopmade
jump lead to connect pin 30 to pin 87 b
(identifications 3 and 7 on Central Electrical
System). The fuel pump should now operate."

Paul902

Hmmm...when I made my emergency jumper I did not put a fuse inline with it. I would say that one would want to use a fuse equal to the rated current of the fuel pump. I have no idea how much current that is.

Kika

Isn't it just as easy to carry a spare relay?

Vorsicht

Mine looks like this one, no fuse. I have not gotten around to it. Here is a pic and instructions for its use:

http://www.clarks-garage.com/shop-manual/fuel-05.htm

Vorsicht

If you want to use a fuse how about using one that is the same rating as the one in the fuse box (fuel pump fuse). Peter

Paul902

The one I made is actually an immobilizer bypass for no-crank situations, and is a simple piece of wire with a male spade connector at each end. For the DME, I only carry a spare relay, not a jumper.

TMc993

I carry both a spare relay and 3-wire jumper...No fuse on the jumper since it's only used to confirm that the relay is bad (I've used it once for that purpose)....I would think that if you wanted to use a fuse on the jumper, you would just fuse it like the 15 amp fuse on the fuel pump circuit...No?

ilko

Paul, could you please elaborate on this? What terminals do you connect and what relay is it?

Thanks!

Paul902

It is R61. You jumper terminals #87 and 30. The relay is for the starter, and is controlled by the Immobilizer. If you have Immobilizer trouble, and the starter will not crank you can jumper the relay, instead. Saw this info on here somewhere. I'm not sure how frequent this situation is, but the jumper is cheap insurance.

Edit: I was mistaken about the effects of bypassing R61. Jumping this relay will let the car crank, but will NOT allow it to start. Not sure what that does besides wear out the starter...

ilko

This is great, thank you! I've never had issues with the immobilizer on the 2 993s that I've had but it's good to have options in case of trouble.

Paul902

Yup! I've not had immobilizer trouble, either, but when my DME relay gave out during a lapping session, it sure was great to have the spare handy. Having this little wire assy aboard may come in mighty useful someday.

nine9six

Paul902,
This is what I was looking to make...Is the wire 14 gauge? I was thinking of adding maybe a 15A fuse between spade ends.
Thanks for posting a photo!
...and yes, I do carry a spare relay.

IainM

I'd pick wire gauge to match the crimp spades, even 22ga can handle pump current in an emergency
Isn't the circuit already fused?
I have one just like the picture but putting a label with the relay contact #'s on is a good idea

Paul902

I think IainM has good advice here on matching the spades. The 1/4" spades I used are stamped 22-18 ga. I think what I used is 18 ga, it was just a piece I had sitting around. Although I made and marked this for the Immobilizer bypass, I did use it this summer in place of the DME relay to run the fuel pump. It ran continuously for several minutes with no issue.

In Vorsicht's link it shows a three terminal jumper, rather than my simple two terminal jumper. As noted above, I could run the fuel pump (with it with the engine not running), and nine9six references a two terminal jumper from the manual. Anyone know offhand what the purpose of the third jumper terminal in Vorsicht's link is, or is it superfluous?

IXLR8

Paul, the DME relay is a dual relay. Power in (30) and power out (87 and 87b). Follow the paths on the schematic and it'll be clear.

That is the way I made mine.