No start...no cylinders firing

[Bigoledave]

My 1979 Porsche coupe in excellent condition
will not "fire" suddenly.

Recent work done:
Installed new battery
Added 6 qts of oil

So....I installed a new battery..and it started up
and idled OK in six seconds or so. The car was
sitting in my garage for months with no useage
or even starting.

After the engine ran fine. I checked the dipstick
and there was NO oil shown. Yes..I have a
leak which I know about and have not fixed.

I then added almost six quarts of 20-50 so that
the dipstick showed full. I did this with the engine
off.

I then tried to start it and there is ZERO firing at
all. I waited an hour....same thing.

I am stumped and have these wild ideas:

1) The fuel pump is not working suddenly.
2) When I installed the new battery I pulled back
the snap on felt cover over the electrical panel.
The black plastic cover has been off for..years?
3) I need to look closely at a schematic of the
fuel system and try to debug there.
4) I bought a cheap service manual....it is on its way.
5) I read that the fuel system has several strange
sounding sensors in it.

Ok..bottom line...what would cause the engine to
not fire or start at ALL after a routine oil addition
procedure. If I overfilled it is there some sensor
SW system that stops the fuel pump?

When my manual arrives I guess I will grab my
dvm and start tracing it out.

Comments and suggestions appreciated.
-Dave

[yelcab1]

You did not know how to check the oil? Do it with the engine idling at temperature. Here is what I would do if I were you.

Wait overnight, drain all the oil from the engine and the oil tank (do you know where that is?)
Refill it with 8 quarts of oil of your choice.
Fire it up.

If it starts, wait for it to warm up, check the oil lever while engine is idling, top up to half way between min and max. STOP.

If it does not start, now we have bigger problems. Come back for more.

[pampadori]

if you are full on a stone cold engine, you are a couple of qts too full. You must only check the oil when the oil temp gauge is registering at least the first bar on the temp gauge. This takes a solid 30 minutes or driving to achieve.

This is not what is causing your no start issue though.
Check for spark. If you have spark, check for fuel pressure. Pumps are very common on these esp if left to sit with E10 or E15 fuel in the tanks for months.

[PeteKz]

Ditto what pampadori said about the oil level is not causing your no-start. There is no oil pressure switch that shuts off the engine if it loses oil level or pressure (I wish there was).

Fast and easy test: Spray starting fluid into the intake and see if it fires briefly. If so, you have spark but lack fuel. Then look for the reason of no fuel.

Do you hear the fuel pump run at any time? A check for that: remove the air filter and turn on the ignition switch, then push up the air metering arm. You should hear the fuel pump run and the injectors squeal. If not, find out why.

[Bigoledave]

I just saw the note about the fuel pump perhaps is not operating...as yes..it has been sitting for months. So...perhaps this was proven when I jumped the #6 wire on the electrical terminal panel to the # 5 and saw a very small spark..which may indicate that the fuel pump IS getting power..but is "stuck" in some way and does Not operate.
Very good info.fom Pampeforis post. Thank you!!!

[boyt911sc]

Originally Posted by Bigoledave

I just saw the note about the fuel pump perhaps is not operating...as yes..it has been sitting for months. So...perhaps this was proven when I jumped the #6 wire on the electrical terminal panel to the # 5 and saw a very small spark..which may indicate that the fuel pump IS getting power..but is "stuck" in some way and does Not operate.
Very good info.fom Pampeforis post. Thank you!!!

Dave,

Could you share with us the test you did above regarding bridging terminals #5 and #6? Which panel was it? A picture would help. Thanks.

Tony

[Bigoledave]

nothing fancy just a jumper interesting there was a very small spark seen when I connected the,...now I am going to measure current with a dvm when I connect them...this will be interesting to see to undrstand why the fuel pump does not operate but...possibly..it is drawing current

[Bigoledave]

"......Do you hear the fuel pump run at any time? A check for that: remove the air filter and turn on the ignition switch, then push up the air metering arm...."
Responding to that post by Pete kz.....
...I am unfortunately ignorant about where exactly the "air metering arm" is located..photo or description appreciated.
THANK YOU!!!!!!!

[PeteKz]

That is the arm that holds the metering plate in the intake funnel. That is under the rubber boot on the top of the CIS, right side of the boot. Remove the air filter and get your head sideways and look up in there and you will see it.

Another way to make the pump run is to unplug the connector on the front (towards the front of the car) of the air metering unit. You will need a mirror to see that.

Yet another way to make the pump run is to remove the FP relay and jumper from terminal 87a to terminal 30.

But first, does it fire on starting fluid?

[Brian Cameron]

Further to PeteKz, remove the air filter cover by unhooking these rubber bands:



Once the cover is off, the fuel metering arm can be seen at upper right of the air filter housing:



As Pete suggests a quick check with starter fluid is a good idea once you get the air filter cover off. But if you’re out of starter fluid, lift that arm with ignition in the “run” position and you should hear the fuel pump run, sort of a whirring sound from underneath the front of the car.

The fuel pump is mounted on the front suspension cross-bar (underneath metal protection plate). SAFETY WARNING ⚠️ if you end up replacing the pump, the gas tank will empty itself onto you and your garage floor or driveway and you could end up like the Fantastic 4 Human Torch.

There are several players in the fuel pump circuit, first there is a relay in the fuse panel, the one furthest toward the back of the car. Then there is a automatic speed, limiter circuit hidden way up behind the gas hood lifter on the driver side. And of course, the ignition switch, and then the fuel pump itself. Check your PMs.

EDIT for posterity: and last but not least, the blue 25A fuel pump fuse, in the sixth position from the rear of the fuse box. If it's blown, the fuel pump will NOT run.

[Bigoledave]

great info...thanks very much. Moving the arm test I figured out
and it is a no-go on the fuel pump.......more info tomorrow. Thanks
very much for your excellent photos and comments.
-Dave

[Bigoledave]

thanks to perek and earthling...
great info....I will do that jumper test tomorrow for sure

"....Yet another way to make the pump run is to remove the FP relay and jumper from terminal 87a to terminal 30..."

But first, does it fire on starting fluid?-YES>>RUNS FOR @ SECONDS OR SO AFTER 4 SCOND SF SPRAY

[boyt911sc]

Originally Posted by Bigoledave

I just saw the note about the fuel pump perhaps is not operating...as yes..it has been sitting for months. So...perhaps this was proven when I jumped the #6 wire on the electrical terminal panel to the # 5 and saw a very small spark..which may indicate that the fuel pump IS getting power..but is "stuck" in some way and does Not operate.
Very good info.fom Pampeforis post. Thank you!!!

Dave,

I am asking you again for the second time, what are wires #5 and #6 you were referring in your post? Spend sometime reading DKLever48’s thread about FUEL PUMP relay/socket tests. Communication and feedback are important if you like this problem fixed. Learn the basic CIS troubleshooting procedure instead of doing unknown procedures. Take a picture of these wire terminals so people trying to help you get better information. Good luck.

Tony

[Bigoledave]

[Bigoledave]

Again..counting from the left...I connected 5 and 6.
Now..better informed thanks to all the helpful post I have received,
I am going to do this test NEXT:"....Yet another way to make the pump run is to remove the FP relay and jumper from terminal 87a to terminal 30..."

[Brian Cameron]

In your first post, you mentioned that the electrical cover had been off for years. By that I gather you don’t have info on which fuses and relays do what?

If so, this picture might help; I believe it is correct for our 79s (photo credit user tkmoore “Tim”):



When you mention you jumpered fuses 5 and 6 (on the panel, left to right), that would have been battery (via emergency flasher) to fuel pump fuse. May want to check that the blue 25A fuel pump fuse is still intact ie that the metal strip hasn’t fried in the middle.

[Brian Cameron]

Your fuel pump fuse is circled in red below, I can’t see from your picture whether the metal strip is still intact:



Also the fuel pump relay is the round red thing at top left.

[boyt911sc]

Originally Posted by Bigoledave

Again..counting from the left...I connected 5 and 6.
Now..better informed thanks to all the helpful post I have received,
I am going to do this test NEXT:"....Yet another way to make the pump run is to remove the FP relay and jumper from terminal 87a to terminal 30..."

Dave,

Bridging fuse #5 and fuse #6 is not applicable to your ‘79 SC wiring system. That is applicable for Carrera 3.2 Motronic.

Tony

[Bigoledave]

yes...I saw that too. My mistake.

so...plan is to finally do this test tomorrow."....Yet another way to make the pump run is to remove the FP relay and jumper from terminal 87a to terminal 30..."

[Bigoledave]

...I should be able to see about 12v at terminal 87a....or....terminal 30 when the ignition is turned on I surmise.
So...when I momentarily connect those two...I should hear
the fuel pump run as I understand it. If I do see 12v at this
small jumper...and do Not hear the pump...then I most likely have a "bad" pump.