Hey guys, help needed.

2000 Blazer 4wd.

Problem: After it sits overnight, it won't start. It will crank and then sputter and hiccup. It will take 4-5 times to get it to finally start and run. It will start fine and run great the rest of the daybut then the next morning we play the game again.

What I have done: new fuel pump in May; new battery, fuel filter, and pressure reg in August; new cap and rotor this weekend. The ignition module tested good.

The fuel pressure measures 56-57 with the key on. I hear the pump whine then stop after 2-3 seconds. When it finally starts, the fuel pressure reads about 50 psi and varies between 48-56 when running/ driving. When I shut off the engine, the pressure reads about 58. It will slowly and steadily drop to 38-40 after about 30 minutes. After this point, it may or may not start it is unpredictble. Over night, the pressure will read 0.

So... what do you think? It did not start doing this until about 2 months after I replaced the fuel pump. The fuel sender was bad was the only reason I replaced the pump.

At this point, I am still leaning toward fuel system. Pump crapped out? Could it be the 'spider'? I hate to just throw the money and parts at it. Is there a way to test whether the pump or the injectors is the cause of the leak? Is there a way to get a pressure reading just from the pump? I have been hooking into the valve in the fuel line in front of the dist cap, but I realize this won't narrow my diagnosis to one or the other. I though of pulling the in line from the manifold and block it off any tips?

Thanks

 

just a question...what brand of pump(module assembly) did you install? Sounds to me fuel related but....jp[>:] PS I don't like those fuel readings at idle-and cranking many times first thing in the AM leans me towards pump at this point

 

You can hook in to the fuel line at the fuel filter if yoou have or can get the right connections. By the way I had a 2000 once with a very similar issue in that it took 3 or 4 times in the AM(first thing) 'priming the pump-key on 2 seconds, key off 10 then again,and again then whola it started. It ended up being the pump. good luck.JP

 

It was an ebay find, don't know the exact brand.Should have known it was too good to be true.

Live and learn I guess.

Anyone else have some input to confirm?

 

Any difference between the ACDelco/ Delphi/ GM part? Are they all the same?

 

I believe that there is-in fact I've done probably 100 and never done an AC Delco a second time, ever. I am a believer. Look real close at your fuel pressure tomorrow morning-at the fuel filter if possible but at the fuel rail and when this issue is occurring-what exactly is the pressure-below fifty(50). Let us know. JP[>:]

 

Pressure with key on this morning was 52-54. During cranking it dropped to about 40-42. When I let off, it went back to 54-56 psi. Never did start.

So there is a difference between a Delco, a Delphi, and GM pump or are all 3 the same?? I found one that said it was a Delphi and listed the GM and Delco numbers.

Thanks for the help.

 

I, myself, would buy AC Delco-check out Rock Auto on the web-everyone here raves about them and their prices. JP....PS still could have an issue in the intake but my money is on the pump-see if you can isolate it per the messages above. good luck.

 

Check out THIS THREAD for the book diagnosis of the fuel system.

 

same problem that i have been having for a few months now. i am thinkig my pump is the culprit. i have changed out everything else. my last idea before changing my pump is to test voltage at the pump unit connector.