Installed a new battery, blew a fuse, now my 78 Fuel Injected Vert won't start.

Old battery died :( Boy was it crusty under that seat! Its a wonder it was actually charging and providing enough current to start the car :-0
Installed a new battery and heard a loud "POP" from the other side of the shifter tunnel. Replaced the fuse and as soon as I closed up the little round fuse holder, the second fuse blew too.
Wow???? The vert was running great just yesterday????
Installed fuse number three, and it held, but now the car won't start.
Engine turns over but it won't start. Will check for spark, fuel, compression, etc tomorrow (i.e. the usual troubleshooting routine) but was wondering if any of you may have experienced something similar before?
Any ideas??
Jim
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fenderjw wrote:

Typically, the only fuse under the seat is for the rear window defogger.
Is there any chance that the new battery was installed Reversed polarity? Not all batteries have the same post orientation.
If you want, e-mail me directly.
Speedy Jim http://www.nls.net/mp/volks /
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Thanks for the reply Speedy Jim! No, it was installed correctly, Its nice to know however, what the fuse was for. Its really got me stymied. I guess Ill have to look elsewhere for the culprit if that fuse is only for the defroster. The dang thing was running great on Sunday!!!
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fenderjw wrote:

Go here: http://www.thesamba.com/vw/archives/info/wiringt1.php Download:
http://www.thesamba.com/vw/archives/info/wiring/76-79113wiring.jpg
Do a thorough inspection of the battery positive cable connection. There should be a thick Red/Wh wire and a thick Red wire joining the monster black cable in the battery post connector.
Check especially for corroded joints here.
The reason for all this is that the FI gets all its power from this battery post connection. It may have been disturbed during the battery replacement.
If that checks out, do this test with a multimeter:
Ignition switched On. Connect meter from chassis ground to the Coil (+) terminal (Blk wires). Should read 12V. Now connect meter to one of the ballast pack resistors. These are 4 ceramic tubes on a bracket mounted to the fender well in the engine bay. You should read 12V on any of the ballast terminals. This test will tell if the FI ECU is getting power.
Post back here or e-mail me with results.
Speedy Jim http://www.nls.net/mp/volks /
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Thanks Speedy Jim! I'll run through these steps this weekend and will let you know how it turns out. Jim
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OK, Confirmed that the battery has all three wires connected to the pos side of the battery and that I have 12v at the coil , but I have nothing at the ballast terminals. Guess that means either faulty wiring or bad double relay or ECU?????
Thanks again Jim
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fenderjw wrote:

I have a simplified diagram of the double relay circuit here:
http://www.nls.net/mp/volks/schem/2fi.gif
Turn the Ignition On/Off a few times and listen/feel at the double relay to see if it clicks. If it does click, then you know the trigger signal from the coil + is getting there.
Before replacing the relay, I would measure voltage on the wire feeding all power to the relay. This should be a solid Red wire from the + battery post terminal. Stick a probe thru the wire insulation to get a voltage reading without disturbing anything.
Jim
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OK, will check the voltage this weekend. In the mean time, I used this checklist http://www.type2.com/bartnik/dblrly.htm to troubleshoot the relay. I have power to the relay at pins 88y and 88z (power from pos term of the battery) I have power at pins 86c with the ignition switch in the on position (power from the coil) I have power at pins 86c and 86a while the starter is engaged (power from the coil and starter solenoid) I don't have power, however, at 88d with the starter engaged, which tells me that the relay is not working.
Looks like the relay is not engaging. Could this be from a lack of voltage as you mentioned before, or is some other condition frying the fuel pump relay (remember the pop and two blown fuses when I reconnected the battery?)?
Thanks for your advice. Jim
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fenderjw wrote:

Did you make those tests with the relay unplugged? If so, the readings may not be valid.
Do the test on the Red wire with the relay plugged in and Ign On.
And check whether the relay clicks.
Jim
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Wouldnt make mu h sense to he k for voltage with the relay unplugged would it? All the above checks were made from the back side of the harness using a test lamp with everything plugged in. The inoperative relay bugs me cuz this is the second one in a year that I've toasted. Toasted the other one last year when the internal voltage regulator in the alternator decided to quit.
Thanks Jim
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fenderjw wrote:

OK. Good. I wasn't sure it was possible to get to the back side.
You may be right about the relay.
There are a few for sale on Samba: http://www.thesamba.com/vw/classifieds/search.php Search "Double Relay"
Jim
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OK, replaced the relay, but Still no Joy I have 11.8 volts at the battery, at terminals 88y and at 88y and, with the ignition in the "on" position at terminal 86c.
Assuming that the new, out of the box relay is good, then what else should I check????
Thanks Jim
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fenderjw wrote:

With Ignition ON, check for 12V at the ballast resistors, or at Term #88b.
Next, find out if the fuel pump runs during cranking. Either measure the fuel pressure (at the Cold Start valve connection) or at least listen/feel the pump for running. I would not accept the mere presence of voltage at Term #88d (pump connection) for this although you could check that as well.
If the pump is working, check for spark at the HT lead from the Coil during cranking.
If the ballast pack has power and if the pump runs and if there is spark, then the engine should start.
There are a number of ground terminals scattered around the engine case for the ECU and its component accessories, but I can't imagine these getting disturbed by the battery change.
Jim
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OK No voltage at terminal 88b. No Voltage at the Fuel Pump. Fuel pump doesn't run when when trying to crank the engine. I'm really stumped here . Sounds like the double relay is bad, but I just replaced it. I just cant seem to get the relay to function????????? What caused the relay to engage and to provide power to the fuel pump via pin 88d?? I know that If I cant get the relay to "click" then I will never get any power to the fuel pump.
I've heard that the relay can be "jumpered" to limp home for example. How do I do this to test the function of the rest of the system since I know that the relay is not providing power to the fuel pump in its current state?
On another note, I have the rear window defroster relay disconnected from the car. I haven't been able to fine one locally and the replacements on order, but for now all the wires to the defroster relay are disconnected. Would this have any effect?
Thanks Jim
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fenderjw wrote:

Defroster shouldn't affect the FI.
The pump runs when the starter solenoid sends a 12V signal to the relay. The ECU and ballast pack get power when the Ignition switch sends 12V signal to the (other half) relay.
Try this test: Connect meter from chassis ground to pin # 85 on the double relay plug (with relay plugged in). Pin #85 is a Ground. Turn Ignition ON and crank engine. See if #85 remains at Zero volts. If it jumps up to ~12V, then the Ground is broken.
I'm just guessing here that this might be a possible cause for the relay not to operate.
------------- To "limp", jumper from battery + post to Terminal # 88b and to # 88d. That will power the ECU and run the pump.
Jim
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Jumpered #88d and #88b to the pos battery terminal and she started right up!!!! Now if I can only get the relay to work properly. I am getting voltage between #85 and chassis ground. Only around 8 volts or so, but I guess that means I'm not getting a good ground. Later this evening I'll pull the ground strap and make sure its making good contact with the battery. Ill post the results shortly. Jim
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Problem SOLVED!!!!! Thanks to hints from Speedy Jim! Wend I found the voltage between #85 and chassis ground which indicated a fault with the ground, I pulled the ground strap to ensure that I was getting a solid ground and I found that the small ground wire that was supposed to be connected to the neg terminal of the battery with a crimp on connector, was not making a good connection through said connector. Reconnected the small ground sans the crappy crimp-on connector and now the relay clicks, the fuel pump hums, and VIOLA.... The engine runs. SHE's ALLLLIIIIIIIIIVVEEEEEEEEEEE!
Thanks again for all the hints Speedy.
jim
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fenderjw wrote:

<Phew!!>
:)
T'other Jim
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