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 Unknown,

how is the switchover from gasoline to LPG techically done? Have you verified with chapter 3 and 4 of my compendium that you have correct components installed? Have you measured idle-run CO?

When it comes to a black smoke emitting engine the usual problems typically are:

1. Wrong components
2. Vaccum leakage on MAP sensor
3. No connection to or broken engine temp sensor
4. Hose to MAP sensor from manifold broken or other vacuum leakages
5. Broken ECU
6. Leaking injectors or cold start valve

I do not believe in problems with engine timing or ignition as you say that car runs well on LPG.

 

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