Hello all. My 96 2 door vortec blazer has a shake or vibration when i start to go from a traffic light or a dead stop. It feels like it is out of gas but the gas is full. Its like it hesitates and i cant gain any speed then after a block or so it starts to pick up again. I have owned it for a month and it never did this until yesterday while i was driving for 10 mins. Now today it did it for a few seconds and then not again the rest of the day. It takes about 10 seconds of ignition turning to start but sometimes it starts right away especially when the tank is full. I have heard a fuel pump but I have heard tons of other things it could be so i am not sure and dont have a lot of money to fix things that are already good. My question is does anyone know what it could be or had the same thing happen to them? Thanks in advance and if you need more info i can provide it. Good day.

 

first off i would check the fuel pressure. you should be able to borrow/rent the fuel pressure gauge from your local parts store. there is a schrader valve on the back side of the intake that you can attach the gauge. fuel pressure should be between 55-61 psi and must remain above 50psi for 10 minutes after the pump shuts off.
post your results and keep us posted.

 

Thanks for your response. I can go to auto zone tomorrow. Do you know how much it costs to rent one? Also Is it hard to do and how do I use this gauge?

 

OK well I tested the pressure and it was 55 psi. I also did the check to see if I hear the pump activate and it turned on and sounds good and normal. I think it may be the fuel filter. I will change it this week sometime. Any other suggestions?

 

I had a similar issue and it was carbon stuck in the EGR valve. Was a simple fix but very annoying.

Fuel filter shouldn't be your issue because you checked your pressure at a point after the filter, although if you don't think it's been changed in a while you might as well throw the 20 bucks into it. Best of luck to you.

 

I had bucking at low rpm, changed plugs, wires, cap and rotor.

Fixed

 

Thank you both for your help. Yeah I probably need a tune up as well and change all the plugs and things. Also how do you clean the erg and where is that located? Is this hard to do? What tools do you need? Thanks again guys!

 

1995 and older CMFI fuel pressure spec is 55psi to 61psi. Your 1996 has CSFI and requires 60psi to 66psi. You're lucky it starts at all with only 55psi The low fuel pressure is more than likely is what's causing your extended crank time. What is the pressure 10 minutes after the pump shuts off?

EDIT: A restricted fuel filter will cause pressure to be low at the service port. (If it can't get through the filter, the reading at the service port will be low).

 

Thank you for your response. I am not sure what it is after 10 mins as I have returned the tester. My fuel filter looks really old and corroded. I am changing that this weekend. You know it has not done it to me since it happened. Really weird. I think that may be the problem but I will keep you guys posted.

 

You really need to check fuel pressure AND leakdown, they are equally important. Best to check it several times in case there's an intermittent condition. You should get the same results each time you check it. Ignition ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi. It must remain above 55psi for at least 10 minutes after the pump shuts off.