Black smoke poor running

I have a problem with the D-Jetronic of my Volvo B30 (3ltr 6 cyl).

When I start it on gas, it cranks but won't run. It emits black smoke and smells strongly of gasoline. On LPG there is no problem, it runs smootly.

I have swapped the MAF sensor, throttle position sensor and the ECU. this has no effect.

The ignition is a 123 ignition with trigger point function. When the motor is running and the trigger points are connected, I do not measure any voltage between the triggerpoints. When I disconnect them I see an alternating voltage (with a simple multimeter.
Unfortunaly I am nog shure how to check the function of the 123 ignition.

Does anyone have an idea what could be the cause of the problem?
I am a bit out of options.

Hi Unknown,
Welcome to the forum.
We like to sign our postings here with our first name, This gives the conversation a more personal touch.
Regarding your problems: Did you check the fuel pressure after switching ignition off?
Maybe you have a leakage at the injectors or the cold-start valve.
Please check this at first... then we will proceed.

Regards
Norbert
 

Hi Dr-DJet,

Thans You for responding.

The gasoline to LPG switchover is coordinated by an electronic switch. It starts on gasoline, when the throttle is pushed in and then released it will switch to LPG. The gasoline pump is schut off and the LPG solenoids are activated. I purchased the car like this 7 years ago.

1. Which wrong components You refer to?
2. I did check al components around the intake manifold for leakage . Including the MAP sensor, injectors and hoses. I tested the map sensor and even replaced it.
3. This I will do this tomorrow. (I did check the air temp sensor)
4.checked and in good shape.
5. Replaced by an spare ECU (no effect)
6. I did check fuel presure. 2.2 bar during and after ignition switched off. The injectors give a fine spray, no dripping and give a nice click sound when opening the throttle.

The ignition Will not be the source of the problem, I agree. But the trigger contact might be?

Regards Coen

Hi Norbert,

Thank you for responding. I did responding to your post but I do not see it on the forum? To be sure:

I did check fuel presure. 2.2 bar during and after ignition switched off. The injectors (including the cold start) give a fine spray, no dripping and give a nice click sound when opening the throttle.

Regards Coen

Hi Coen,
did you try to run the car on fuel with the LPG.unit totally deactivated?

Regards
Norbert

Hi Dr-DJet,

I will check if the ECU and MAP sensor are suitable according to the list in chapter 3 and 4. Then I will measurenall sensors after removing ECU.
Allso I will check the way the fuel/ lpg switches are executed.

I will be back with the information.

Regards Coen

Hi Norbert,

In fact I did. I was on my way when the LPG level ran low and switched to gasoline. The engineer stalled allmost immediately with black smoke and gasoline smell.
My Son had to tow me to the nearest gasstation (the shame). Luckely he used his Volvo 245 81’ so we did it in style.

But seriously. I have tried to run the engine on gasoline with the LPG hoses disconnected. It did not have any effect regarding the problem.

Regards Coen

Hi Norbert and Dr-DJet,

First thing to do this morning was checkking the motor temperature sensor. It’s located in a way it is hard to see. It turns out the cable was disconnected. After reconnecting te cable the engine did start and run properly.

Probably the cable came loose during replacing the alternator two weeks ago.

I like to thank you both for your effort to resolve the problem.

Regards Coen

Hi Coen,
thank you for the information.
The missing sensor leads to such effect only when the engine is warmed up. Starting cold wouldn't be a problem, but the engine would begin to emit black smoke after some kilometers and die.

I wish you all the best with your car.
Norbert