Fuel Pump?

'97 Blazer 4.3L Hi! Engine barely runs at idle. As soon as i give it gas it stalls out. Also, when I removed the air intake from the throttle body it dies immediately after making a loud vacuuming sound in the throttle body. As though it is pulling in so much air the mixture becomes too lean to continue running. Fuel pump? Maybe a fuel sensor? If it is the fuel relay would it even run at all? Check engine light is not on. Thanks!

You need to do a fuel pressure check...a test kit is available at most chain type auto parts stores,

http://i131.photobucket.com/albums/p288/Clunk_/Image026.jpg


The reason your motor dies when you take the intake duct off the throttle body is the Mass Air Flow (MAF) sensor is installed on the other end of the duct....you killed the signal so the computer stopped the fueling.

Okay, thank you for your quick response. I will purchase the test kit in the morning.

As Chris says get the gauge on it.
Specs for the 4.3 X and W engine that year.
60/66 lbs of pressure.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

MT

Okay, finally was able to check fuel pressure.

cold, not running = 60psi initially, then drop quickly to about 50, even though i left ignition in on position

running at idle - 58psi initially, then fell to 53-55

slowly able to increase rpm = 53-55psi, stayed there pretty steadily at all rpm's.

could not find a way to effectively pinch off return line. at back near tank entrance was able to pinch off return prob about 75% (semi-hard plastic line). No change in reading. Stayed at about 53-55psi.

would not stay running well enough to do the drive test.

looks like it is the pump then?

Thanks again! ted

You are welcome.
Make sure you get a Ac-delco/delphi OEM type fuel pump.
Aftermarket and Airtex fuel pumps are junk.
Good luck
MT

You are welcome.
Yes but make sure you check the wiring power and ground to fuel pump to.
Make sure you get a Ac-delco/delphi OEM type fuel pump.
And if a replacement plugin is required with the pump always solder the wiring and seal with sealer.
The butt splices that come with the plugin kit are no good on wiring.
Aftermarket and Airtex fuel pumps are junk.
They are sub weak on fuel pressure and a lot of them fail 0-7 and up 30 days after installation..
Not worth the 25-50 dollars you save on them.
Good luck
MT