Well as the title states my blazer has started surging today. I first noticed it when I went on some offroading today. While going up the hills with hard acceleration it started to surge. So I took it easier on it till we were close to my parents home (my dad went with us), and then I floored it, it dropped down to 1st gear (automatic tranny)and started surging again. On the way home I decided to floor it while I was on the highway and it didn't surge again( in gears 2-OD). So I got close to home and put it in 1st gear manually and slowly accelerated till about 5k rpm......no surges. Then I stopped (leaving it in 1st) and floored it, and it immediately started surging again.

So I don't think it is a transmission problem otherwise it probably would've acted funny while I was accelerating in 1st gear (seeing as that is where it always surges).

So I am thinking it is likely a fuel pump problem. But I wanted to see what you all had to say on the subject considering fuel pumps are rather expensive for my blazer.

 

Locked in 1st gear all the way up to 5K RPM=not good.

What's the mileage? I did a cursory search using 'surging' and there are some viable options as a cause. This thread points to a bad catalytic converter after replacing a bunch of other parts. Maybe that will help you out. How does your exhaust smell? Any drop in gas mileage lately?

 

Leaving it in 1st till 5k rpm isn't going to kill it or anything. Heck everyone that jumps on their blazer from a stop does that occasionally at least. If it was the catalytic convertor I think that I would notice a pretty big difference in acceleration all the time though wouldn't I? As for a drop in gas mileage lol, it has always had crappy gas mileage 18mpg on highway average. Got 20mpg once and thought I hit gold lol.

It only has 83k miles on it and the exhaust smells like it always has.


***NEXT DAY***

Well I took it out today and without giving it time to warm up (as the guy had to, in the thread above) I pulled out of the driveway and floored it, it started surging immediately. I don't think that it was even over 1k rpms and it started surging. But it still only surges when floored. Not when you steadily accelerate.

 

Ok got the catalytic convertor replaced yesterday. It did NOT solve the problem. So the next idea is to replace the fuel filter since I have one laying around anyways. And if that does not solve the problem then I am going to take it to a dealership and have a diagnosis done to it.

 

You could always just stop flooring it

justttt kiddding...

Make sure when you do the fuel filter to look for any black-carbony-looking-nasty pieces that may float out...this can tend to indicate a failing fuel pump.

 

Have you cleaned the EGR valve and the MAF sensor? If not, I would have for sure cleaned them before replacing the catalytic converter... This could also be a problem with the TPS sensor where it isn't sending a steady voltage to the PCM at WOT. But again, I would test before you replace!

 

If it was the EGR, MAF, or TPS sensor wouldn't it be sending a code and thus turning on my Check engine light?

Also I think the catalytic convertor needed to be replaced anyways. After it was replaced I did notice an increase in power, so it was probably on its way out the door.

 

A problem with these sensors does not always trigger a CEL. The EGR valve is known to become stuck open with chunks of carbon. The MAF sensors used also get built up with dirt that gets through the air filter and gets worse when aftermarket, oiled air filters are used.

The TPS sensor can be checked with a multimeter, key on, engine off. It should range through 0.5V at closed throttle to 4.5V at full throttle with a smooth transition between the two voltages. If you see it drop out, the sensor is bad.

 

Sounds alot like the problem I had and it was low trans fluid. Check it HOT. I had only checked cold and it looked fine. Finally checked it hot and it was low. Filled it up and my surging was gone.

Alan