help-car wont start!!

isaacyoon · 07-19-2004, 10:18 AM

I have a 76 911 s w/ a 2.7 cis. With the help of my friends, we've put a rebuilt engine in the car. When I start the car, the car will start and run when the key is is in the start position but when the key goes back to the run position, the car stops. I have been scouring the bulletin board and this is what ive done to trouble shoot.

1. I've checked the fuses blocks front and back. All are intact and functioning. I've noted that the 3rd fuse from the top on the back fuse block does have power when the key is in the run position.

2. I've cleaned the 12 pin connection in the back.

3. I've swapped relays in the front w/the fuse block and the one in the back.

4. I've checked for fuel coming out of the injectors.

5. I've checked and changed the gap to .035

6. I've tried to check if power was going to the coil when the key is the run position w/my light probe(im not sure what you call it but it turns the light one when you connect one end to power and the other to ground). I dont seem to be getting the light to turn on.

Any help or insight will be much appreciated.

Paulporsche · 07-19-2004, 02:48 PM

Did you say power was going to the coil @ start, but not run?

These may not be related but did you check your points/dwell? Also check your grounds, ignition wires and dist cap, rotor, and check to see that the dist shaft rotates and springs back.

By the way, the fuel pump relay is the red one, not black. And shouldn't the plug gap be.028?

isaacyoon · 07-19-2004, 04:17 PM

I am sorry. I was talking about the gap in the distributor. I am not referring to the pluggs. I read the .035 gap on another thread on a similar problem w/a 76 911.

I believe the power goes to the coil in the start b/c the car runs when the key is in the start position and turns off in the run position.

The fuel pump works b/c we get fuel to the back.

Any insight why the there would be no spark when the ignition is in the run position?

isaacyoon · 08-16-2004, 05:14 PM

I had an old german friend look at my engine. He said check the alternator b/c it may be causing a short. I have no idea how he figured this out. I found out that someone had wired the ground wrong. I fixed that then I figured that this had damaged my original ignition system. I replaced this w/a msd unit. THE CAR STARTS!!!

I just need to fine tune the car and I will be on the road hopefully in the next 2 wks. I wrote this just in case someone else has a hard start and does a search. This might be helpful. Thanks Paul for your reply.

Early_S_Man · 08-16-2004, 07:19 PM

Issac,

The proper point gap is 0.35 mm or 0.014" ... I don't think you will be getting any closing of the points with a 0.035" gap!

Jim Sims · 08-16-2004, 07:55 PM

Check to see if you have switched the connectors for the air flow switch and CSV. Here's a section from a previous reply on the topic:

However, if you are connecting the wiring harness plug for the air flow switch to the cold start valve (CSV) instead of the air flow switch, the cold start valve circuitry will ground the circuit, energize the relay coil and cut power to the fuel pump(s). The connector for the air flow switch is higher up and just below the fuel distributor on the front (car's front) of the CIS system; the wiring harness plug that attaches to the airflow switch should be painted green or have a green dot on it. The CSV is down lower on the front side of the CIS system and it's wiring harness connector should be painted blue or have a blue dot on it. If these two connectors are correctly installed then check the air flow switch to see if it has continuity across the terminals. Put a VOM (voltage ohm meter) or powered 12 volt test light across the terminals and lift the air flow meter arm; if there is continuity when you lift the arm then there is a problem with the switch.

Jim

RoninLB · 08-16-2004, 08:57 PM

Quote:

Originally posted by Jim Sims

will ground the circuit, energize the relay coil and cut power to the fuel pump(s).

Fuel pump red relay. Think about the guys info.

Jim Sims · 08-17-2004, 02:43 AM

Didn't see the guy's final post. I don't believe the diagram you posted is correct (at least for a 1976). When closed (no air flow), the air flow switch provides continuity in the circuit which causes the fuel pump circuit to unlatch when the ignition key switch is in the on or run position. This is why one can disconnect the air flow switch connector and still run. Cheers, Jim

Paulporsche · 08-17-2004, 11:32 AM

isaac

I just noticed your subsequent post. How did things work out? Do you still have points in that dist?

BTW the figure of 35 that you have should be degrees of dwell in your points, not the gap, as someone else pointed out. You should get/use a dwell meter and make sure the gap is correct. I like to set mine when new @ 36. Then as the rubbing block wears down and the gap goes down, the dwell angle goes up. It should then be changed @ max 41.

isaacyoon · 08-17-2004, 02:46 PM

Thanks for the information. Next time I work on the car is sunday. I work to pay for porsche parts and that's my next day free. I cant wait. I will have read this many times before then and I will update the post. but by God, this car will RUN!

The funny thing thing is that I had threatoned my wife and said if the car didnt start last week I was going to buy a 993. Now my car starts but runs roughly.

RoninLB · 08-17-2004, 03:22 PM

Sensor plate Switch.

isaacyoon · 09-15-2004, 05:09 AM

Latest update.

Jim Sims must be clairvoyant. I was working on the car and saw smoke in the back. A bad fuel pump relay caused parts of the wire harness to melt. I replaced sections of the wire harness. Then when I tracked all the involved wiring I realized that I flipped air flow switch and the csv. That was corrected.

The problem now is the car still doesnt start. I definitely have fuel. Ive pulled the injector and checked. I have huge spark from my MSD. I will try again to adjust timing but I am going to review Ronin's suggestion of a sensor plate switch. I will also check the airflow switch continuity.

thanks

ps If i cant this thing started by november, a boxter from Mannheim never looked better!

isaacyoon · 09-17-2004, 01:37 PM

Ive got it running. Sometimes the basics are the most important. I had only checked one fuel injector for fuel. I pulled the others yesterday and several were blocked. I cleaned them and the car runs. I figure this would be good information if anybody else pulls a search. Thanks again for all the help. Now I have just a stuck accelerator and brake pedal.