I've a fuel starvation problem. The symptons are that when I've been driving for about half an hour if I try rev it up the revs start droping at about 7-8-9K and if I continue pushing the accelerator one of two things can happen:

1) The revs drop, then go up, then drop again

http://youtube.com/watch?v=QLtAsWiQb44

2) The revs drop like a stone and if I don't release the pedal and push it again they drop until the motor stops!

http://youtube.com/watch?v=OWe4ZYnTQ0c

You can see both things, and a combined one, in the following videos:


1) for some seconds, then 2):

http://youtube.com/watch?v=TPud13-WTVU

Another one:

http://youtube.com/watch?v=lsqTbmF0W_k

The difference in this case with the other starvation threads I've seen here is that in my case there isn't any difference if the gas is at 1/4, 3/4 or full. I use premium unleaded 98 (I think it is 95 there.)

I recorder those videos because I suspected that my local garage would not be able to reproduce it, because it's in Madrid and at work hours there is a lot of traffic.

I took the car to them, and they found a very small crack on my cat and to be sure (the car is under warranty) they changed it, that was yesterday but today it took no time to happen it again.

Oh...

I USE(D) PREMIX

Sorry for my eng"r"ish.

 

Any CELs?

Ideas:

Coils gone bad <
Clogged fuel filter << (likely premix)
Bad fuel pump
ECU is putting engine in safe mode for some reason
Some sensor (temp, air pressure, etc) is defective

What and how much premix do you use?

 

No cels and no codes (I've a canscan). About 3 ounces (100 grams, 0,1 liters.)

 

My guess would be the fuel pump.

I had a bad one and the symptoms were similar.
If it was a filter, you would have more trouble with acceleration, when you use maximum fuel.
If it was "safe mode" the computer would limit revs, say below 4k.

Mine would only happen when the car was hot, the revs were high (7,8,9K) but only when the fuel was below 1/3rd tank.

The pump has a high and a low pressure relay, you could jumper out the relay to make the pump go "high" all the time, then see if it re-occurs.

S

 

Thanks Stealth, I think it's the pump too, but I wonder why I'm the only one to have this problem with the full tank. The 7 may (I'm out of Madrid until then) I'll tell the garage chief to try it to be sure it's the fuel Pump before Mazda continues renewing my car piece to piece (not that I care while it's in warranty but...)

 

New fuel pump installed and problem fixed.

No more premixing for me, thanks.

 

Videos youtubiz'ed for better viewing of my former misery!!!!

 

How much premix were you using again? 3 oz for how much fuel?

 

For every full load, that is, about 14 gallons.

 

My car only had fuel starvation doing high G left hand turns. On the straights, everything is normal until I turn left. The car would bog down (similar to a fuel cut out in a very extreme way) and onces it settles, the car would rev to and beyond redline.

I've also had my fuel pump replaced.

Check out the stuffed sock filter.

NB: I premixed and also used LUCAS UCL.