Help - Djet running way too rich Options

[Halfnelson]

Help - my new to me 1973 1.7 Djet came running really sweet, but almost immediately developed the 'hunting tick-over' of lean running / air leak. We replaced all the vacuum pipes, found one of the inlet gaskets had a very slight leak. Seems somewhere along the line things have been tweaked to compensate for the leaks so that now they're cured, the car is running super rich. Having had a L-jet for years the Djet is new to me so any advice on where to start first would be much appreciated. Thanks Chris

[914_teener]

Time Out.

There is a difference between testing and speculation.
Testing is methodical (there's a method) and speculation guessing albeit it MAYBE somewhat educated guessing.

FIRST IS TO Confirm the right parts to the engine. Has this been done?

Let the OP provide results.....I think there is a lot of speculation that throwing partsat the situation is testing and not confirming that a component or system is good. A system is component driven. You need the right components for a 1.7.
First off...is it in fact a 1.7? How do you know that it is? Let’s ASSUME your cam is the stock cam and not another grind. Has the engine ever been rebuilt to your knowledge? You can measure valve lift and degree the cam for duration to be sure.
Make sure all the mechanical systems are within spec. This includes valve function and piston compression specs FIRST. Any failure or out of spec situation here means that you haven't assured that the engine vacuum system mechanically is functional or functioning properly. If not, D-jet won't function properly if at all. You don't have to have the engine running to do this.
Air-Fuel -Spark
Vaccum
If you’ve checked your valves and compression and this is ok then the next thing to check is the actual system for vacuum leaks...everywhere the is vacuum. You mention that you did this, but a smoke test under vacuum is a very definitive test. Instead it reads like you just visually tested the components and not the intake system like the plenum and all the parts installed. This Do a smoke test to make sure there isn't a crack there or anywhere else. There are threads here on how to do it….safely.

As far as the MPS is concerned...I had an instance where the Diaphragm was cracked and only intermittently would leak which did the same thing...dumped fuel like crazy into the manifold and cylinder to the point where the fuel vapor coming out the exhaust like a white fog and gas dripping out of the tip.

So when you do a test on the MPS you should pull it to about 12 HG and test it for leak down overnight. Make SURE you test it for leak down and not just for a minute or two. Any leak down could mean it is only slightly cracked or it is leaking somewhere. You also did not mention if you testing it electrically. All of this procedure is listed on Brad (Paul) Anders website with addition of all the component testing for the D-jet system. We’ll assume you’ve done this and all the D-jet components test good.

Fuel:
It doesn’t appear that you have a fuel delivery issue except from your post, it appear you have a mismatched injectors….maybe. If you’ve had check for components for the 1.7 D-jet you probably would have picked this up already.
Testing for injectors is best left to hydraulic bench and electrical testing for pintel function and is best left to a house that specializes doing it. Its well worth the money and aggravation. Forget baby jars or coffee cans as a test. They will check mostly for flow rate…that it..not worth your time.
Fuel pressure test is essential and easy to do at the test point at the driver side fuel rail. Check also the fuel tank sock and return lines. and all fuel connections for safety, correct type and for cracks while your’re there. Make sure the fuel pressure is to spec and you don’t need the car running to do this.
Testing for a bad CSV is simple. Just bypass the fuel line for it. There is a gasket there…however youv’e done the smoke test already so don’t worry about it. You found no leaks…right?
Spark:

Again we’ll assume you have done a component checks and testing and if good the only check are for there installed function. These are mostly electrical connections such as the ground contacts and wires for the CHT, wires and contact to the head. The test for these are resistance to ground and if either the head thread is dirty and the ground lead to the ECU is not cracked or grounded properly the engine will not run. Period.
The CHT is a thermistor so it is resister to ground but it must ground to provide a signal to the ECU. The full test is to ground the lead and see if the engine will run. Again…if you have tested the harness you know either the CHT is bad or the ECU and if you tested the CHT and the ground points then it HAS to be the ECU. I hate the threads about bad CHT when very rarely do they actually fail.
As already mentioned the dizzy is a big issue, but you should have already confirmed that it is the right dizzy for that displacement and functions properly including the advance and retard vaccum can.

When I fist bought my 73 914 (now almost 20 years ago) I removed the entire top end including all the D-jet parts. I checked them all, cleaned them, and serviced and tested the injectors. I replaced everything that didn’t test or check to spec. It ran flawlessly. In that time I had three failures. The MPS, the ECU and then the dizzy. I replaced the dizzy with a 123 unit and it ran better than it ever did before.

If you do all of the above and mostly in that order your car will be well sorted and provide many years of enjoyment as it did for me. Sometimes I regret selling it but looking back now…years of fun and friends.

Good luck and wrenching.