I have a Walbro fuel pump on my car. Since I Installed It, I have been getting horrendous fuel economy. Now, my car doesn't want to idle. I tryed to spin the motor by turning the main crank. Nothing. It's locked. I'm at a lose of words here. Can anyone help me.

Not being able to turn the main crank Is whats bothering me the most.

 

I doubt the Walbro caused that.

 

I've changed the oil 5 times in less than 1000km's. all times oil was thinner than water.

 

Definitely not the Walbro. Have fun rebuilding your engine

 

So main crank won't turn whats that mean?

 

Somehow your engine is apparently seized. Bad news. If your oil has been really thin and you have changed it several times then that was a very bad sign to begin with. It sounds like your main problem was just coincidentally at the same time as your pump change. The car may still be rich but that wouldn't lead to an engine failure.

 

could have ran so rich you washed all the oil from the omp off but ive never heard of that before. you probobly accidentaly goofed something during the install.we all have done it......
good luck.