2000 GMC Jimmy

[fellasdad]

I have a 2000 GMC Jimmy with the Vortec 4.3 V6. The Service Engine Soon light cam on and the truck died. I am getting 50 psi of fuel pressure at the shroeder valve on the fuel line just at the TBI. with the ignition on. The motor will turn over but wont crank. When I manually introduce fuel into the TB it will run rough until the fuel is consumed. Any ideas?

[MT-2500]

Originally Posted by fellasdad

I have a 2000 GMC Jimmy with the Vortec 4.3 V6. The Service Engine Soon light cam on and the truck died. I am getting 50 psi of fuel pressure at the shroeder valve on the fuel line just at the TBI. with the ignition on. The motor will turn over but wont crank. When I manually introduce fuel into the TB it will run rough until the fuel is consumed. Any ideas?

Fuel pressure is way to low.

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.

[fellasdad]

When it does run the psi is about 65. I just replaced the map sensor and it ran briefly about 10 seconds and it shut down it then attempted to start with out the splash of fuel in the tb

[fellasdad]

but it wont run now on its own

[MT-2500]

Originally Posted by fellasdad

but it wont run now on its own

What is engine cold cranking fuel pressure?
Run as much of the fuel pressure test as you can.
FULL DIRECT PRESSUREN AND ENGINE CRANKING PRESSURE FOR SURE.
Post back pressure readings.

[MT-2500]

Originally Posted by fellasdad

When it does run the psi is about 65. I just replaced the map sensor and it ran briefly about 10 seconds and it shut down it then attempted to start with out the splash of fuel in the tb

That should be telling you the problem.
50 and no run and 65 and it runs.
Your no run is a bout 15 lbs of pressure short.
Find out where it is losing pressure.
Go threw the fuel pressure test as outlinded or as much as you can do on a no run.
Post back your pressure readings.
That should point you to the problem.

[Rick Norwood]

How many miles on this truck? My 2000 Jimmy lost its fuel pump at approximately 105k miles. MT is giving you good advice on the testing, but it sure sounds like your fuel pump is shot. If it is, stay away from the cheap aftermarket replacement pumps and go with an AC-Delco, and don't forget the new fuel filter.

[djd99]

Originally Posted by Rick Norwood

How many miles on this truck? My 2000 Jimmy lost its fuel pump at approximately 105k miles. MT is giving you good advice on the testing, but it sure sounds like your fuel pump is shot. If it is, stay away from the cheap aftermarket replacement pumps and go with an AC-Delco, and don't forget the new fuel filter.

I don't believe millage is a good indication of when the fuel pumps go out in these trucks, My pump went out at 75,000 so anything after that is a bonus in my book also my tranny went out at 80,000 witch in my mind is way too early, but if you drive em you have to maintain em...... Don't buy acdelco pumps off ebay to save, learn by my mistake them pumps are rejects and the seller won't stand behind them. I ended up buying a acdelco pump from carquest for 290.00 and if you add what I spent on the acdelco ebay pump I paid full dealer price... U live and learn...