d-jet issues...not the typical questions

[norustscott]

so, it has been a while since my last posted...in fact I have not driven my 914 for almost a year. And of course i have a new D jet issue. First some back ground data

Mine teener is a 73 2.0 with a complete 74 djet system...everything is compatible and was working well up till yesterday. it is a well sorted out rebuild with about 40K on the clock...on the way home from work yesterday eve she just died. I will spare the 45 minutes of road side disgnostic rambling...but here are the facts.

I have a fuel supply issue but,
[LIST][/LIST
]The fuel pump is good and runs when is is supposed to
Fuel injectors, trigger points and throttle Position switch are operating

I did take the time on the side of the road to take the air box off and suck a few ounces of fuel up from the fuel tank and into a vaccum line, and pouring it into the intake manifold. This enable the engine to idle for about 30 seconds but the throttle offered no increase in rpm. It will also run briefly if you cycle the ingnition to pump up the system and dump fuel into the manifold by operation the throttle. I also bumped the started to alternate trigger point contacts...if I do this a couple of times i can get the engine to stumble and try to start...but just barely.

Now...I sat on the roadside will cell phone in hand read to call for a tow...but I thought about the fuel issue and thought how I could increase fuel rate without any real tools...I came up with disconnecting the Head Temp Sensor ( HTS) this would normal cause the engine to load up with fuel and die...I tried it and wow...the engine started and I was able to drive relatively smoothly for the 20 miles home.


At home I check the sensor and it tested good. ( crap) I reinstalled the sensor and the same scenario ... it runs but only when the sensor is disconnected, while it is running and i reconnect the HTS, the engine will die.


This is a fuel supply issue for sure. but what is malfunctioning? why is the engine so lean that the extreme rich condition under normal fuction can operated the engine.

I am going to test the fuel pressure next...but what else am i missing? ECU? MPS? BTW all of the components are relativly new prey the aux air valve...


help...this one is going to be a *****...


Scott

[John Rogers]

I would say to pull up the step by step for troubelshooting the complete DJET system which I think is here on the Pelican site and go through it step by step. Make sure to write down ALL readings you get and then post them all here. Also post the numbers of the brain and any other year specific electronics so we can determine if there is a mis-match.

[Dave at Pelican Parts]

I would suspect a fuel pressure problem. A gunked-up filter, a plugged inlet, something like that.

Someone I know had a problem where their D-jet car would only idle, and die when they opened the throttle. They started troubleshooting, and found that the CHT was unplugged. They plugged it in, and the car wouldn't even start at all! Eventually they found that the fuel pump relay was bad, and gravity was the only thing that was feeding fuel to the engine. The pressure was low enough that unplugging the CHT sensor just allowed enough fuel to dribble out for the engine to idle.

Anyway, get a pressure gauge and check the fuel pressure.

--DD

[norustscott]

So I checked everything with the last being fuel pressure...fuel problem solved...bad pump. The bad pump put out 3-5 psi...very low but not too low that disconnecting the head temp sensor would signal the injectors to fire and run very rich...

filter also needed to be replaced......replaced the already front mounted pump with a 74-76.



thanks for the feedback...back on the road again.


Scott

[jamcleod]

great! now you can drive to the East Coast Cookout on Sept 15th! now, how about Andy's car?

[norustscott]

running now as well...brain was fried...the fuel pressure regulator bad... caused a circuit in the brain to cook...looks like an over time issue...years maybe. solder finally gave way and let the magic smoke out...Replaced both and off we go...

[RibeiroFerreira]

This is my first post!
I have a 1972 2.0 914 and I am driving it every day to go to work. A few months ago the engine started to die after drive more than 30 km. I discovered that the problem was dirty trigger points so I removed the distributor, clean the trigger points and the engine was good again. But after driving another 30 km I got the same problem. Now the engine runs no more then 5 minutes after cleaning the trigger points then it dies and runs another 5 minutes after recleaning them again.

Do you have any idea of why the trigger points are getting dirty so fast? The distributor seal ring is new, the trigger points are relatively new (10.000 Km), the fuel pressure sensor is new and the throttle valve is also new.

Many thanks for any help