2000 GMC Jimmy loss of power hard start ect...need help!!!

A few months back my jimmy started losing power and wouldnt climb a hill or get out of its own way, I did a tuneup plugs/wires distributor, rotor button, fuel filter, pcv valve ect, still same problem eventually it wouldnt started very hard after sitting for a week so took off the catalytic convertor off and still no change, there is no service engine light on, the only way i can start it now is with starting fluid after it sits and then it idles fine but still no power once im moving. The vehicle will start back up after its been started once and will continue to till it sits over night. I did a fuel pressure test and with key on its 60 psi, with engine running at idle no load its 54 psi and when i rev it up it will only go up to about 62 psi when i shut the vehicle off it holds at 60 psi, im at a loss here and have no idea where to look next and im not sure if the pressure are where they should be, any help would be greatly appreciated, thanks

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.

Any codes or check engine lights on?

no there is not check engine light on

my guage isnt long enough to actually drive the vehicle and see and i have to get a different adapter to check the direct pressure from the fuel pump, Im still wondering if the psi that I posted is right or is it low, by the sounds of it they are alittle low so i guess I should be leaning more towards the fuel pump, I replaced it 3 years ago, but I guess its failing again, any other suggestions??

You need to get a longer hose so you can test it hot on the road running and when it is acting up

Specs are 60/66 lbs.

On the road you should see 63 -65 lbs pressure depending on engine load.

Cold start you should see 65-66lbs of pressure.
And on a full pressure test you should see 85 lbs or more.

You should never see anything under 60 lbs.

Ill get a longer hose and see, even when I rev it up in neutral it bogs down around 3000 rpm and will not go any higher, so I figured if im getting a reading of 54 psi at idle then the pump is weak??

Could also be fuel pressure regulator or fuel filter or low voltage to fuel pump.
Go threw the complet fuel pump test and also check for 12 volts to fuel pump and good ground.
Post back all pressure readings.


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.

I have 12 volts and a good ground, Cold start I have 60psi with the key on not running i have 54 psi with the car running at idle and have 58-62 psi while driving and when i turn the key off it holds at 60 psi so i still need to test the fuel pump pressure tomorrow, is there a test to check and see if the regulator is bad??

Key on not running is not the cold atart cranking pressue.
As outlined inthe full pump ressure test.
The test for the pressure reg is to block the return line and see if pump comes up to full pressure.
If so then the pressure regulator is leaking by or leaking is it does not hold pressure to specs.
Of 65 key on or engine cranking.

when i turn it over to start its 60 psi the same as when the key is turned on

that is about 5-6 lbs to low.
you need 64-65 lbs to squirt injector cold.

Post back pressure readings from full test.

Also make sure your gauge is reading right.

I have 74 psi direct from the fuel pump I still havent checked while driving so thats the next step

Well Installed a new fuel pump and filter changed the oil and it fired right up but then I noticed gas leaking from underneath the vehicle, when I got it back on the lift the fuel line that runs from the evap was very rusted and when I got the line out it was blocked with rust, so Im replacing all the fuel lines and hopefully things will be fixed the only place to get the fuel lines is through GM so I should know in a couple days if that was the problem. But It was running the same as before I changed the pump so im assuming the problem from the start was the rusty fuel line

I would find the leak before
\
Before throwing parts at it and assuming it might be this or that.
Start with doing the proper testing.

If you give us all of your fuel pressure readings we might be able to help.