I have a ’99 Blazer 4x4 4d with a 4.3 engine that is often hard to start (2nd or 3rd try), hesitating (between 2,000 and 3,000 rpm) and getting 16 mpg (with 50/50 city/highway driving). I bought it with 120k on the odometer, so I had it tuned up (plugs, wires, cap) and replaced the partially blocked cat. After this I still had the same symptoms, so I cleaned the MAF, EGR (with new gasket) and replaced the PCV valve. Same symptoms. My gas gage also dives from full to empty after around 175 miles. I am wondering if my fuel pump/sending unit is next on the replacement list. I have not tested the fuel pressure, as I do not have the tool(s) to do this. Any thoughts or comments? Thanks.

Jeremy

 

Buying a fuel pressure gauge shouldn't break the bank, ~$20 for a cheapy. I've had mine around for going on 12+ years and it was a cheapy to begin with. Testing the fuel pressure really is the first step in determining if the pump is at fault.

Your fuel mileage is not bad for 50/50. Some get better, some get worse...

On the hesitation. How bad is it? Does it feel like the truck misses and only at that RPM? Is it consistent regardless of throttle position? OR does it do it more while gently accelerating? OR more when accellerating at wide open throttle?

 

I should probably look at buying a pressure gauge. I notice the hesitation under light to moderate acceleration. It isn't terrible, but any passanger (like my wife) will look at me and give the "what is that" look. If I rev the engine in neutral, it doesn't seem to miss.

Jeremy

 

My local NAPA store tested my fuel pressure last night. With the key turned, it jumps to between 40 and 60 psi, but then immediately falls to 0 psi. The pump should hold at 60 psi for starting, correct? It looks like I'll have the pump changed as soon as I can burn up my full tank of gas.

Jeremy