fuel pump fuel pressure results
pensfan74
06-22-2008, 05:52 PM
I had my blazer looked at by my mechanic, and he said my fuel pressure was reading at about 52 lbs. He thought that my pcm might be bad and did not have the right diagnostic equipment to check it so I had to take it to the GM service dept to have it checked out. Their results were that the pcm checked out to be working, but they said my fuel pressure was reading between 45 - 52 lbs of pressure and said it was probably the fuel pump. The fuel pump that is in there now IS one of those junk airtek fuel pumps. I dropped the gas tank AGAIN today and saw that my back fuel lines were connected ok all 3 of them, but towards the front of my gas tank i noticed that there was another little inlet that was NOT connected and I am guessing that is where a vaccum hose is supposed to be connected for the vapor line which I must have forgot to reconnect when I put that airtek pump in. Could that be why I am getting those readings or is the fuel pump junk. this blazer ran great for about a month or two before I had problems again with starting up and getting low pressure readings. I have the pump ready to pull out and return, the gm dealer wants $450 for a fuel pump. the airtek one was about $270. Could someone reccomend one that will be ok that is not an airtek but not as high priced as the gm dealer one? What about ac delco or delphi. Also my lock ring is pretty much junk can I get a new one of those for the top of the gas tank where the pump fits into? I would greatly appreciate your advise because I miss driving my Blazer and want to get it going ASAP...
MT-2500
06-22-2008, 06:15 PM
What year and engine?
Airtex fuel pumps are on the bottom of the barell junk list.
You are on the right track about AC-delco?delphi fuel pump.
The dealer pump is Ac-Delco/Delphi but at full dealer price.
They are.
Around 300 US dollars at a good aftermarket parts place.
Check Carquest and AZ and O'reilly And other parts places may be able to get them and tell them you want a good AC-Delco/delphi pump not a 90 day wander or Junk airtex pump.
They also have or can get the fuel pump retaining ring.
If vent valve is broke get another one or if just unplugged plug it back up.
But to be sure it is the fuel pump run the full fuel pressure test.
May be to late if the tank is down.
But should have been done when the repair shop checked it.
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.
Airtex fuel pumps are on the bottom of the barell junk list.
You are on the right track about AC-delco?delphi fuel pump.
The dealer pump is Ac-Delco/Delphi but at full dealer price.
They are.
Around 300 US dollars at a good aftermarket parts place.
Check Carquest and AZ and O'reilly And other parts places may be able to get them and tell them you want a good AC-Delco/delphi pump not a 90 day wander or Junk airtex pump.
They also have or can get the fuel pump retaining ring.
If vent valve is broke get another one or if just unplugged plug it back up.
But to be sure it is the fuel pump run the full fuel pressure test.
May be to late if the tank is down.
But should have been done when the repair shop checked it.
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-2500
06-22-2008, 06:54 PM
Also check your parts ticket on the airtex pump.
It may be under warranty depending on where you got it.
If it is ask for your money back on it and or get a exchange/adjustment on it for the good ac-delco/delphi fuel pump.
And file a labor claim for having replacing it.
Airtex will kick labor claim it back and swear up and down there is nothing wrong with it.
But the big parts places can make them eat it.
Carquest has droped all airtex pumps and went to ac.
Sometimes the ac pumps are even cheaper at parts place than the junk Airtex pumps.
Good luck
MT
It may be under warranty depending on where you got it.
If it is ask for your money back on it and or get a exchange/adjustment on it for the good ac-delco/delphi fuel pump.
And file a labor claim for having replacing it.
Airtex will kick labor claim it back and swear up and down there is nothing wrong with it.
But the big parts places can make them eat it.
Carquest has droped all airtex pumps and went to ac.
Sometimes the ac pumps are even cheaper at parts place than the junk Airtex pumps.
Good luck
MT
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