This can't be right?, D-Jet Options

[McMark]

First things first.

Does the fuel pump run for 2 sec. when you turn the key on? If not, solve that problem first. Don't worry about starting the engine or how it's running, etc until the fuel pump is running reliably. I think your relays, your relay board, or the fuse on the relay board are the problem.

Then address the fact that the fuel injection is running RICH enough to kill the motor. Check your CHT connection to make sure it's not grounding out. That's the most likely culprit.

[FlatSix]

I did make the mistake of buying an 'OEM' pump from China. It was a POS and I wasted many hours trying to solve a problem that was not there. It is now safely in a box! The fuel pump I have now is a Bosch, made in Germany, part no. 580 464 070 which will pump more than enough fuel!

McMark is correct, there are two separate issues to solve here:
1. Sometimes the fuel pump will run for 2 seconds when key is turned;
2. After running for about 2 minutes (cold?) the car stalls and won't restart.

[Spoke]

1. Sometimes the fuel pump will run for 2 seconds when key is turned;

This should (must) happen every time the key is turned ON. If it doesn't happen sometimes, there could be an issue. It is difficult to hear the pump if you are in a noisy environment.

[swl]

Fues on relay board - Isn't this 'downstream' of the relay i.e. between the relay and the fuel pump. Therefore if the relay is not switching this is not the cause? I will check it though but I'm thinking the fault lies elsewhere.

On the contactor side of the fuel pump relay (30-87):

Battery
Pin 14 of the 14 pin connector
passenger side fuse terminal
fuse
drivers side of the fuse terminal
Pin 30 of the FPR
contacts of the FPR
Pin 87 of the FPR
Pin 13 of the 14 pin connector (signal also available at pin 12 of the 12 pin)
Positive terminal of fuel pump
fuel pump
Negative terminal of fuel pump
Ground connector (not sure which one)

If there are opens along that path the solenoid will still make but the fuel pump won't run. From watching the threads over the years the most likely culprits are the fuse connectors followed by brushes on the pump.

Spoke is right - hard to hear the pump at times. For an intermittent like this I wonder if it might save time to tap in an idiot light right at the pump. Then you would know for sure when the pump is getting power.

Another tap point would be the left side of the fuse. That should always be on.

[swl]

2. After running for about 2 minutes (cold?) the car stalls and won't restart.

There are at least 2 major affects from warm up:

1. The AAR starts closing down. This should gradually reduce your revs to normal idle speed.
2. The CHT starts leaning out the mixture.

In the extreme either of those two or a combination could stall the engine. Throttle feathering should compensate and keep the engine running if it were one of these two. Could you catch the stall on film? That worked well on your early post.

[FlatSix]

I've made some progress. I've taken apart and inspected wiring to ignition switch and main fuse box. This didn't show up anything notable to report.
I plugged in the fuel injection test box I purchased from James T. I went through the tests and everything checked out ok so I went to start the engine. The fuel pump ran and the car started as you would expect. The engine did not stall after a couple minutes unlike previously.
I disconnected James' box and went to start the engine. NO fuel pump running for 2 seconds. Connected the test box back up - everything ok! Repeated exercise several times. I have now 'bent' the connectors on the white plastic strip in a little and that seems to have solved that issue.
So I can now get the engine running. I'm not sure about the idling though. Have a look at the video. The revs oscillate between about 900 to 1800. Note the CHT sensor is new. When I use the test box to read the resistance of the CHT it is in line with what it should be (about 500 ohms, the engine isn't that warm yet). When I use the test box to substitue for the sensor and I 'dial in' about 500 ohms for the resistance then the engine idles smoothly at about 1200rpm.


https://www.youtube.com/watch?v=gvRmkUeS024

[r_towle]

wiring...
ohm your FI harness to verify you dont have a short in the CHT wire.

Rich

[FlatSix]

In trying to test the CHT white harness wire it broke! Luckily it's right by the connector so I won't loose too much length when I re-solder it. The rest of the wire dosn't look to be in great shape. I may just bypass the wire and put a new wire in from the CHT sensor to the brain's connector. Has anyone else done that?

[r_towle]

Jeff Bowlsby makes complete new FI harness setups.
He has what you may need.

look him up here...good man with all the wiring knowledge and pieces you could want.

Rich

[FlatSix]

I'm thinking a new harness would be the most reliable option.

[Rockaria]

has anyone mentioned checking the ignition switch. If so, sorry I did not see that post.

EDIT: Slits did mention the switch.

They are cheap and easy to switch out. I had this exact problem with mine. The ignition switch looked fine but would only work for a while but once warmed up the FI and pump would stop.

I took out the switch to find a very small crack. Installed new switch and the car ran perfectly.

Just in case,

[FlatSix]

Christopher,
Having thought about this a bit now, I'm going back to basics on this one and am going to replace the ignition switch. Looking on the bird site they only sell Chinese ones which the reviews say are problematic, just what I don't need.
I’m going to put a WTB on the classifieds to see if anyone can supply a German ignition switch for a ’76.

[Porschef]

Christopher,
Having thought about this a bit now, I'm going back to basics on this one and am going to replace the ignition switch. Looking on the bird site they only sell Chinese ones which the reviews say are problematic, just what I don't need.
I’m going to put a WTB on the classifieds to see if anyone can supply a German ignition switch for a ’76.

Chris,

The OEM switches are available, I ordered mine directly from a Porsche dealer. In fact, I'm headed over this morning to pick it up. I have some other errands to run, but will report back once I return home to let you know what it looks like. I had gotten a Beck-Arnley part that looks and fits fine, but after reading about some of the reliability issues some have had, was reluctant to use it. Ill keep it as a spare.

I removed the one in the car yesterday, it looked exactly like the one shown in George's book. A small crack that was making the car more and more difficult to start; in fact, I could not start it after the last time it went into the garage. Had a bit of difficulty removing the housing, but stuck with it and it suddenly came off. What I thought was a bad crush sleeve was actually just a loose 6mm cap screw that holds the assembly to the car. But I've got a new sleeve coming also, and will replace that at the same time.

Joe

[McMark]

Joe, some pictures of the box and part would be extremely appreciated! (IMG:style_emoticons/default/smiley_notworthy.gif)

[r_towle]

Joe, some pictures of the box and part would be extremely appreciated! (IMG:style_emoticons/default/smiley_notworthy.gif)

(IMG:style_emoticons/default/agree.gif)

[Porschef]

Here it is! It is for a 76, which I think goes back to 73. But I'm not certain.

Now to go install it. Yeah!!

[FlatSix]

That photo was just too much for me. I've just ordered a new one from my local dealer. Porsche UK are showing stock available in the country so I should have it next Wednesday.
I can't do anything to the car this weekend as I'm taking my youngest son to a sailing competition along the coast at Weymouth, the sailing venue for next years Olympic Games. That could be more stressfull than an intermittent 914!

[SLITS]

3 different switches

'69 - mid '72 .... hard wired into loom

mid '72 - '74 ....

'75 - '76 ...

Difference between the last two is in the securing screw & shape.

[FlatSix]

I ordered the same part number as in the picture. The packet even says 'Made in Germany'!
I'm just trying to remove the old switch. I believe I need to remove the metal plate to get at the screw. Is that correct? If so how do I do that? I've tried putting the key in but that made no difference, that metal plate is still there. I've tried levering it out with an old small screwdriver but to no avail.

[KELTY360]

This link will take you through it step by step.

Pelican Parts Ignition Switch Replacement