Blazer stumbles when accelerator pushed hard. No error codes present. Only 54,000 miles.
Problem started when I was backing out of parking space at store.
Thought it was possibly out of gas. Changed battery and added gas. Wouldn't start then I dumped a thimble of gas down the throttle body and it started.
I was clear across town so I hi tailed it home while noticing the stumbling mentioned above. Ran perfectly smooth while at cruise speeds.
Changed the fuel filter yesterday. After a few on-off of the ignition key to prime the lines it started right up.
Right now it won't start but tomorrow it might.
I can hear the faint sound of the pump running for a few second when the key is moved to the on position, then again when moved back to the off position.


I think it is the fuel pump but would like some confirmation before I go to all that trouble.
Thanks in advance.
Mark

 

It could be the fuel pump, could also be the FPR.
Do a fuel pressure and leak down test.

 

Yes, check fuel pressure at the test port on back side of intake. Probably time to replace the fuel pump.

 

I really don't want it to be the FPR. Looks like dropping the fuel tank will be easier. Since it was not too expensive I purchased a fuel pressure gauge.
I will report back the results.

 

48 at first. Steady. No noticeable leak down.
Vehicle would not start.
I used the pressure relief drain hose on the gauge to give a shot of fuel into the throttle body.
After the shot of fuel and a few cranks it started.
While engine was running, the pressure was between 52-54. The gauge needle was vibrating between those two pressures.
After turning the vehicle off, the pressure was 52. I relieved pressure several times to see the 52 number again and again. The vehicle would not start again. It seemed closer to starting then it did before the shot.
What do you think?

 

I decided to clean the MAF. The filaments were very dirty. That seems to have helped the starting problem. Now vehicle will start with a little finessing.
However, it still hesitates when throttle is opened. Even a little bit.

 

After cooling down for a while I tried to start vehicle again. Although it did start, it was not the normal "bump" the key to start.
Had to go on-off-on-off. Finally got it started then turned off to try again, on second try it was hard starting with all kinds of bucking etc.


Cleaned IAT, seems a little better.

 

This morning I tried to start it to see what would happen when it was cold.
It didn't start up on first turn of key but did on the second. It stumbled a bit, then idled perfect. Started and stopped a few more times.
This thing is driving me crazy!
Any ideas?

 

Fuel pressure needs to be 60-66 psi key on engine OFF. Pressure should be 55 psi or more after 10 minutes of the pump turning off. If the pump does not reach this pressure you will have trouble with the engine starting or running

 

OK time to replace the fuel pump. Ordered AC Delco replacement based on posts saying not to use aftermarket.

The manual is pretty straight forward on procedures except I don't know how to release plastic "rivets" that hold the fender flap in place. I need to remove the flap to get to the filler hose connection. The hose needs to disconnected to drain the tank before I lower it.
I have attached a picture of the flap showing the plastic pieces. If anybody knows how to release those connectors, the info will be appreciated.
Thx, Mark