83 911SC Electrical problems, no start

[roadster49]

Just took delivery of a 1983 911SC. The transport driver said he drove the car onto the carrier and it ran fine. It would not start when he tried to get it off the truck at my home, so he rolled it off and we pushed it into my driveway here in Michigan.

I charged the battery and with starting fluid, I could get it to sputter for a few seconds, but it would not run. I jumped 87a and 30 on the FP relay, but the fuel pump did not run. I jumped the FP from the +battery and the pump ran.

The car has an alarm system but it is not connected. When I did connect it, the FP still did not run. Fuse 16 has no power. The wiring is cobbled, but if it ran to go on the truck, I am thinking something shook loose and that is why it is not starting now. I have contacted the PO but have no response.

Other observations, there are 2 black wires running from the front trunk to the inside of the car that have been cut. There is a toggle switch in the ash tray that has been jumped. Some splicing has been done in back of the fuse panel.

Here are some pictures:




Help!

[yelcab1]

i think you start by removing the after market alarm system. Then we will figure out why the Fuel Pump is not getting juice.

[LWJ]

Lets start with some positives: 1) you just got a really cool toy! Congrats. SC's are great. I just got out of mine 5 minutes ago. 2) the PO left a bunch of loose change in the ash tray! Bonus!

On the the diagnosis. First, do you have a good schematic? My recollection is that Bentley may not be the best for this. I think the Haynes manual has a good schematic. If you want me to check, send me a PM. They are both buried right now.

Old alarms suck. Bad wiring sucks as well. It seems you have confirmed that the fuel pump is a culprit. Could a funky ignition switch do this? They do go bad.

What you need to do is consult the schematic and circuit by circuit test this. I hope you can put this in a garage as Michigan in the winter sounds ccccold!

Keep us posted. I agree that the truck ride changed something. It will be a piece of cake once you find it. Finding it will take a little effort. Also, when you do your testing, take good notes so you can cut the crap alarm out later.

Good luck
Larry

[schumicat]

the toggle may be a kill switch. I would trace the wiring on it. also look at the fuse diagram and see if any of those crimps relate to the fuel pump. crimps are notorious for coming loose. SCs are great cars.

[boyt911sc]

Roadster,

Could you test terminal #85 (FP relay socket) for ground? Use a test lamp/light and connect one end to the (+) terminal of the battery and use the other end as probe for (-) ground contact. If the test lamp lits up, proceed to the next test.

While the test lamp is 'on', push the AFS (air flow sensor) upward and hold it up. I want to see what's the effect on the test lamp. I got a few ideas why the FP is not getting power. So I'm trying to eliminate one possible culprit at a time. Thanks.

Tony

[roadster49]

Test Lite "Lights" at (+) battery terminal and probe in #85. Proceeded to next test.

With AFS in up position, test light is not lighting. When released, test light lights.

Feedback from PO. He said to not step on the gas when starting, to let it start and then give it gas. but this is not starting at all and I did not step on gas.

Thank you.

[boyt911sc]

Originally Posted by roadster49

Test Lite "Lights" at (+) battery terminal and probe in #85. Proceeded to next test.

With AFS in up position, test light is not lighting. When released, test light lights.

Feedback from PO. He said to not step on the gas when starting, to let it start and then give it gas. but this is not starting at all and I did not step on gas.

Thank you.

roadster,

The test results indicated that the car alarm unit is not attached to cause the FP not to run. The AFS is good and working. The PO is correct in his advice to you. Put the car in neutral (hand brake on) and turn the ignition switch to start the engine. Never step on the accelerator or use starting fluid to facilitate starting. This is a fuel injection system and not a carburated engine.

Additional FP relay socket tests: Using the same procedure to test #85, but reverse the connection of the test lite/light/lamp to the battery. Hook up one end to the (-) ground terminal and check the following:

a). With IS (ign. sw) @ ON and relay pulled out, check terminals #87a, 87, and 86. Terminals #87a & 86 should have power; #87- none.
b). Check fuses #11, #12, and #16 for power. Both fuse terminals (upper & lower) should have power when IS @ ON.
c). Test FP by jumpering terminal #30 (FP relay socket) using power from battery. Use a wire jumper preferably with an in-line fuse added. If you don't have one, just make the connection to #30 very briefly (tap & off).

Let us know what you get. It would tell you where the source/s of the problem (non-FP start) and fix it. Keep plugging the information coming. I like to make the FP run before New Day. The clock is ticking and we'll wait. Thanks.

Tony

[boyt911sc]

Originally Posted by schumicat

the toggle may be a kill switch. I would trace the wiring on it. also look at the fuse diagram and see if any of those crimps relate to the fuel pump. crimps are notorious for coming loose. SCs are great cars.

roadster,

Trace where the two wires lead to and where the wires of the toggle switch are connected. These are not factory set-up and got to be identified first before doing any further inspection work. Keep us posted.

Tony

[roadster49]

With "IS" on no power at 87a, 87, & 86 (test light grounded to - battery terminal) probe used in sockets.

Fuses light up at 11 & 12. No lite on 16

FP runs at #30 jumped to + battery terminal

Toggle switch is not connected. Note the one picture where the orange and black wires are connected under the dash. I will check where they go in the car next.

[schumicat]

does the relay get power from fuse 16? i would change that fuse. these types of fuses can have corrosion that prevents them from working sometimes even when not blow. In fact I would add replacing every fuse with new on your list for down the road.

[roadster49]

Thanks. I already changed the fuses on 16 & 17 and rotated the others

[Joe Bob]

I agree, shyte can the old alarm.

According to Bentley and my experience.....you need to check grounds and power at the relay, and fuse 16. It requires at the minimum a test light. I prefer a multimeter as it gives you a number on the voltage and can give an indication of partial connectivity.

Once you establish power and grounds at the relays or lack thereof, you can proceed to lifting of the flapper and testing the fuel pump.

BTW, you have a PM.

[roadster49]

I followed wire in cabin. Toggle switch is bypassed the wires going to it are joined with wire nut. see pic

Found another push button switch with red and blk wires, it does not seem to work and is bundled into a heavily taped set of wirees see pic. Found a little red light in that circuit which also does nothing whatever I push.

Traced the orange and black wires into trunk. Blk wire is spliced into fuse 16 (which does not have juice) and orange to 11 that does not have juice when IS is off. When on from previous test it had juice.

There are also 2 wires that are cut...not sure where they go or came from see pic

So if 11 has juice, it should be feeding 16 when ignition is on, or am I getting ahead of myself?

Here are some pics.

[schumicat]

the red light is very likely related to the alarm (blinks when ignition off to deter thieves). where is that other push button? if it is kind of hidden I would guess it is the valet switch for the alarm (deactivates alarm). fuse 16 powers the fuel pump. if it is not getting power with ignition on that could be your problem.

[roadster49]

See picture two above. It is between the steering column and the heater control mounted into the dash. I think the valet switch was in the ashtray as shown in pic 1. it is not connected and the blk and orange wires nutted. Yea 16 needs power when IS is on

BTW I ran the fuel pump through relay #30 for a second during the earlier test, and the little engine sputtered to life for a second.

[Mattlock18]

Sounds like you have quite a mess there. I would check the simple things first. Make sure the ground strap under the car didn't get jarred loose during the trip on the carrier. If that's not it you'll probably have to continue going through the wiring. I have had a couple electrical issues in my SC (also here in Michigan). With one, it would start fine sometimes and then others I'd get nothing at all - turned out to be a bad solenoid in the starter. I spent a lot of time looking at wires, etc. before figuring out it just needed the new starter. The other time, it would start fine most of the time and then on occassion wouldn't pump any fuel to the engine. Turned out there were a couple exposed wires that had come through their casings that my mechanic found, which were causing intemitant problems. He fixed them up and solved the problem.

Good luck and let's hope for a short winter here in MI so we can get these SC's back on the road.

[roadster49]

Amen, this car is in the driveway and subject to the elements. its warmer today so trying to get her running.

[roadster49]

Well I must have messed up something tracing the wires, 85 is not lighting now. went back through but could not get it back on....

[boyt911sc]

Originally Posted by roadster49

With "IS" on no power at 87a, 87, & 86 (test light grounded to - battery terminal) probe used in sockets.

Fuses light up at 11 & 12. No lite on 16

FP runs at #30 jumped to + battery terminal

Toggle switch is not connected. Note the one picture where the orange and black wires are connected under the dash. I will check where they go in the car next.

roadster,

When IS @ON, fuses #11, #12 & #16.............all three (3) should have power but only #11 & #12 have power!!!! Fuse #16 is directly wired from fuse #11 so the line between #11 - #16 is 'open'!!!!!

Are the black & orange wires some what connected to either S11 and S16? You mentioned something about these wires but do not completely understood it. S16 should have power for the FP relay to work!!!!! This is your first and foremost goal to fix. This is electrical 101 and the very fundamental wire connections!!!!!

You could make the FP relay socket work by simply connecting S16 to S11 (see factory wiring diagram circuit #48). But before you do this, I like to find out what happened to the original wire (RED) between these 2 fuses. Had it been cut/ altered/spliced or something else(???). Look carefully at the fuse panel and inspect the input end (top) of the fuses (S11 & S16). S16 should have a red wire directly connected to S11 and S11 should have 2 wires going in as per factory wiring schematic!!!!! Take a look and see what you have. This is where the problem is. This a 10-minute job to fix it!!!!

I want to understand why S16 fails to energize the FPR socket before doing any immediate repair. Lastly, could you take picture of S11 & S16? I believe we are very close in identifying the culprit/s. Keep us posted.

Tony

[boyt911sc]

roadster,

After re-reading your ealier post with the picture of the fuse panel showing a close-up shot of the black & orange wires, my suspiscion has been re-inforced. Based from your information and pictures, the black wire is connected to S16 and the orange wire to S11. This is encouraging info.

Connect the black and orange wire and turn the IS @ON. Now check terminal 87a and 86 (FPR) for power. They should have power this time. Am I correct? If 87a & 86 have power, plug the FP relay back. Before starting the engine let's do check the FP first. Pull out one injector out and place in a container. Turn IS @ ON and lift the AFS very briefly. Did you get some fuel out from the injector? If you did get some fuel, you have successfully energized the FP.

Place the injector back and start the engine. You should be ready for a drive. Let me know what's the outcome...........Happy New Year!!!!!

Tony