About a week ago I was driving my car when it suddenly started sputtering and driving almost like it was out of gas this stopped and I left it alone. The next day the same thing happened, and to overcome the sputtering I accelerated faster and it was no longer noticeable. (This is mainly happening once the engine heats up) Now it is terrible, I cant drive a half mile without it bucking with acceleration and dying at a low idle while in drive at a stop sign. I have been driving it to test things that I have fixed which have not fixed the problem yet.

I have replaced these things:
Spark Plugs, Spark Plug Wires, Distributor Cap, Distributor Rotor, Throttle Position Sensor, MAP Sensor and the Fuel Filter. I have cleaned/checked the EGR valve, Idle air valve, vacuum lines electrical connections, fluids, and inside the intake plenum where it seems clean (no broken/leaking lines).

I feel like I have done everything possible, but I know there are a couple more sensors I could change, and possibly change the fuel injector/pressure regulator.

Whats next? Has anybody had something similar happen?

Thanks

 

before you do ANYTHING else check fuel pressure. it must be above 59ish at key on and hold above 55 for 10 min. if its low replace pump,if its good then slowly drops its probably the spider.

If you replace the pump,ONLY buy ac delco. these blazers are so picky on pumps. dont chance it like me,and 40000000 others did. We ended up doing it again.

 

Actually if inside the plenum is clean it means something is leaking. Either the fuel pressure reg is leaking or the injectors are leaking. Its normal for the plenum to be black and sooty looking.

 

Sorry, I should have specified more. It is clean as in there is no pooling of fuel, and it is not abnormally filthy or clogged up. I cleaned it several months ago too and put a new gasket on.

 

I am new to the site AND SIGNED UP BECAUSE im having this SAME issue.

 

for the both of you. A bad area in these are the fuel systems aka pump and spider injection. Whenever they start to go out,you will get all kinds of hard starts,flooding,rough idles,sputtering etc. A simple pressure test will tell you if you have a fuel issue. You can go to autozone and borrow a pressure tester for free,but you have to leave a deposit in case you dont return it. You get every penny back when you take it back.

 

How much they charge you for deposit? I am working part-time so I don't make much.

 

I'll be doing that today. I'm guessing autozone will charge $50 for the tester... thats how much one costs new and thats how they price.

 

I THINK it was like 100 bucks. I dont remember. They usually charge more since the parts are usually a higher commercial quality since they are being loaned out. call and ask..

 

Alright, today I got the fuel pressure testing gauge. I followed all of the directions that were included and got the running test, acceleration test, and battery (system priming pressure) test. The pressure range that my Jimmy is supposed to stay at is 56-66... That seems like a large range.

So I turned the ignition on, but not the engine and the fuel pressure jumped up to 64, but then instantly dropped. It took it about a minute to reach 20. After that I turned the ignition on and off to pressurize it more and it did the same thing... it just couldnt hold pressure.

I then turned the engine on and the pressure jumped up to 56/57 and stayed steady for the most part. If I pulled on the throttle it would jump up about 1 and as soon as I let off it would drop down to 52/54. I tried the same in neutral and it was just a bit more extreme, but not too much different. (The car sputters while in neutral, but not park)

So what it seems to me is that my fuel pressure is low, and it does not hold pressure while the engine is off (which it is supposed to I guess). So what now, can anybody think of any other ways to test it, or different things I could try before I return the pressure tester?

Thanks... let me know