Excessive fuel consumption in Isuzu

I have an Isuzu 94 Sw Naftera and is consuming too much fuel (gasoline). We made it see for two mechanics and they do not find the problem. They told me that the Lambda Zonda is ok, the injectors are ok and even opened the air pass and remains the same. The truck also has two gas tubes and the same happens in gas. Can someone guide me to know what to do? Thank you!!!

If you have excessive fuel consumption (whether gas or gasoline) it is because the air/gasoline mixture is too high.

I am not very much on the LPG. Another thing that can go crazy is that you have an air intake in the exhaust, for example the collector or multiple joint to the broken or lazy cylinder head. If this occurs, the external air enters the exhaust that falsifies the measure of the Lambda probe and despite the fact that it is not damaged, it detects oxygen in the escape and is notifying the switchboard that the mixture is poor and therefore you have to enrich it.

Another factor to take into account is that of motor temperature probes, sometimes the thermalors are given measurement error and inform the calculator that the engine is cold when it is actually at a service temperature and is drowning due to excess fuel due to the dosing for cold start.

If you have a scanner, pass it, it would also be good if you said if the \ "Check Engine \" was lit "because if so, it means that there is a failure memorized in the switchboard and from there you can quite notice the search for the failure.

All the best.

Thanks for your answer !!!!
Regarding your end of the end, Check Engine turns on the board. I'm going to make someone check the switchboard.
I thank you again for your answer. I am desperate because nobody finds the problem. I'm going to check all the points you mention. Then I warn you if we find the inconvenience.

Thank you!!!