78 911 SC - Fuel Pump issue

[opticalfuel]

Short history: Recently: as of 3 months ago, I dropped my engine to at least change out the bad ring starter gear. Well it turned out I had an opportunity to really clean up the engine and get some parts spruced up ( mostly all cosmetics) and get the engine really clean.



I did so with pretty good success; http://www.opticalfuel.com/slideshowpro.htm



So now I have put the car back together, and now she won’t run. The problem has been narrowed down to the fuel pump. No fuel pressure, and it’s not coming on.

The fuel pump is pretty new(2years old at most). I know it works, after taking it out and inspecting it, and applying 12v to it. It spins – believe me. While I was at it, I cleaned it up, and tightened the connections.



I checked the fuses, they are fine. The relay is brand new, and it made no difference if I replaced the relay with the adjacent relays.



Also I tried fooling with the socket a bit, rocking it back and forth.



NOTE: >>> The only thing that consistently made the pump activate was plugging in the red relay partly: using only the three prongs (excluding 86, 87a)

That DOES fire up the pump, but only if I hold the relay like that.



This leads me to believe a sensor or a wire somewhere is mis-wired.

Can you suggest a way to troubleshoot this to track down what on 86/87a (on the relay) could be causing the shut down of the pump?



I am pretty darn sure I got the wiring right, but if there are any spots on the wiring harness that I am not 100% sure of it is TWO areas:



The alternator / generator wiring – although the dash lights show green and red lights as you’d expect…
The wires that go to the ‘fuel injector type’ connector on the Aux Air sensor… (right side of engine looking into the deck lid: bolted to the 5th cylinder intake)
Possibly the connectors for the Air flow sensor, and cold start valve could be swapped, but I think it’s highly unlikely – I don’t think they reach opposite ways


So … do you think we can get her running again?



I am really stumped.

[2.7RACER]

Good morning,
The fuel pump runs when the fuel pump relay is not energized.
If you suspect the wiring to the air flow switch and cold start valve is switched unplug both, then see if the fuel pump will come on when you crank the motor.
The Air flow sensor plate may be stuck. Pull the air filter out and find the arm and plate. Raise it carefully to determine if it moves freely.
A further check is to raise the air flow plate with the ignition on, once the plate moves up slightly, the air flow switch should go open, this will cause the fuel pump relay to de-energize and allow the fuel pump to run.
You'll notice with the ignition on now, if you pull the fuel pump relay it will click off. Or as you slowly insert the fuel pump relay it will click on.

This is normal.
It should click off if the wire to the air flow switch is disconnected. Once it clicks off the fuel pump should run with the ignition on. Don't let the fuel pump run more than a few seconds.

[opticalfuel]

Ok....

That is the same advice from another source I trust. I must have in-invertently swapped the coldstart valve sensor plug and the air flow switch plug. I am in the process of switching that now.

I'll report back as soon as I see how that goes.

[opticalfuel]

That did it. It is running. Now I just have to tune, tune, tune.


First drive --- coming up...

[opticalfuel]

Another interesting chapter in the saga of this machine.

I swapped the plugs as you know, and it made it run, but not very well.

The paint job and baking of the catalytic converter didn't bode very well. It only ran for a few minutes and then plugged itself up!! The sucker turned bright red hot and I knew there was something not right.

Swapped it out for my old cat - with no internals, and it seems to be OK. When I checked the cat that I replaced... it had pieces missing from the mesh. Not good. I just paid 400+ bucks for that last spring. Crap.

I will have to replace it again. Anyways ... the exhaust pipe is still kicking out chunks of hot ceramic waste. Not cool! LOL.


Also: I started to tune it and was not very pleased with the running. It had occurred to me earlier that perhaps the rotor was a gear off.

Sure enough, I reset it tonight after setting the engine at TDC... Z1, and resetting the distributor (rotor) to match. It seemed to run much smoother after doing so.

However, it was getting late, and I had to quit. The sound of the engine (especially with no cat) is pretty loud... and bassy... so I didn't want to annoy the neighbors.

I bet it'll run almost perfect tomorrow.

Now ONE question remains.

FOR the distributor: WHERE do I connect the opposite end of the vacuum line?

I am pretty familiar with the throttle body, so please just reference which terminal (small tube) I should connect it to. There are two on the rear, and two on the front (toward the rear of the car)

Which one is the proper place to get the vacuum for the distributor?

['78 SC]

This should help ...

[opticalfuel]

I have a perfect solution to the whole thing.

Check this out:

I called Mobile Works West. Contact:
MobileWorksWest@aol.com


The guy who owns that is a Porsche Genius. He had my car totally fixed within a few hours. It was AMAZING!! He had an entire shop in the back of his truck and handled everything.

He only charged me 318.00 including a $100 FEE for travel to Sacramento area. Very reasonable.

I was more than happy to pay it. I am going to place a promotion on my website for this guy!!!

His name is Tom Amon, and he is talented. He straightened out the running of that motor.

How well? This well:

I had the confidence in the work and the sound of that engine to drive it 300 miles today!!! I drove from my home in Roseville > San Jose, Los Gatos, and home again, and the sucker didn't miss a beat.

NO PROBLEMS!!

This car is a joy. It is running perfect again.

WOOOO HOOOO!!!