Indy Rev

LOL no Bill, the pump is coming out. I was just trying to get it to run so I could diagnose other issues with the car.
Still cant figure out why the FP wont run without being jumped from the battery. I tried to use a jumper at the relay, but that didn't do anything.

Bill Ball

With the wiring diagrams you can trace the current flow to the FP. Working backwards, 12v+ comes from U15 on the CE panel from fuse 42 and the FP relay output. If you jump pins 30-87 on the FP relay socket and the car starts, then it's either the relay or one of the feeds to that relay. Check that that pin 86 sees 12V when the ignition is on. Pin 85 gets a ground signal from the LH, but that is only on start up and continues only if the LH gets a crank signal that the engine is running. The fact that you have spark tells me that this signal and the alarm are OK, because if either were not working you would not have spark. If jumping the FP relay socket 30-87 does not power the FP, verify that 30 is seeing constant battery power which comes into the CE panel at U12 and that there is continuity in the output path to the FP as I mentioned at the beginning of the paragraph.

Anyway, that should get you on the path.

Indy Rev

Thanks Bill. I will check that out tonight. I did jump 30-87 and the car had no signal to the pump. I also checked to make sure the kickdown had the proper relay in it. I saw that somewhere on a thread. will check 30's power.

auzivision

Hi Sean, Welcome to the online aspect of the shark tank and glad to here you already have her running.

Just so you know, I have a complete set of 928 Workshop Manuals. If you want to borrow the binder with the wiring diagram, stop by on your way home... or I can run it by, but it will cost you some more of that home made brew!

Indy Rev

Thanks Kurt. The wife has to work early tonight so I have to run straight home, but if you want to swing by for some cider your more than welcome to. The electrical diagram would help.

Indy Rev

I feel like I'm going cross eyed looking at this small print out of the wiring diagram. I have power to socket 30. I have power to 86 when the key is on. If 30 and 87 are jumped I do not have power to the fp. Now I pulled fuse 42 15amp and it was broken. Replaced it and the car fired up then 4min later died so I pulled fuse 42 and found the fuse not just blown but melted.

If I understand all of this correctly, power comes from 30 to 87 then to fuse 42 to U15 and out to the fuel pump. So I toned out u15 from the ec to the fuel pump and got tone, then decided to tone u15 and a ground and also got a tone I unhooked the lead on the fp and tone went away.

Is it possible that the fp is grounding itself out and tripping fuse 42?

Hilton

edit: nevermind my original comments - 15A is correct fuel pump fuse.

Have you cleaned the ground points on the car? I also recommend threading an M8 bolt into the chassis-side of the battery earth strap, and using a battery jump lead to make a temporary known-good ground from it to the negative terminal (a corroded ground strap isn't uncommon - due to battery vapours and moisture).

Indy Rev

The ground strap is good and the strap point has been cleaned. Also cleaned the ground points the the ec attach to. The strap was one of the first things I checked.
My first thought when I saw the fuse was that it was the wrong size.

SteveG

By what means did you check the gr strap? the point is, visual is not enough.

Indy Rev

I inspected it by sliding the sheathing enough on each end to confirm that there is Un-corroded shiny copper under there.

danglerb

If you get the workshop CD set, like Roger has at www.928srus.com you can put a .pdf file of the electrical diagrams on a CD and take them to an office printing place like Kinko's and have them output on the large format printer for about $10. I did my model years in I think 17x30 inch sheets.

Jim Devine

Go one step further & have them laminated. That way you can use markers from a dry erase board to trace wires . When you are done, just wipe it off. Learned that one from a long time shop owner. Also companies that do blueprints can enlarge. I asked how big they could make it & the guy asked how big is your wall?

Indy Rev

Nice. That sounds awesome.

Indy Rev

So back to the question what would make fuse 42 melt?

hans14914

Bad fuel pump pulling too much current.

Stick your ammeter in there and see what the pump is pulling.

This tool is invaluable for quick checks of things like this, or finding parasitic drains in a system:

http://www.harborfreight.com/30-amp-...ter-67724.html