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2001 bravada hard start


xracer1
09-17-2007, 12:03 PM
I have a 01 v6 bravada with a starting problum After sitting overnight it will start after cranking it twice. When it gets to normal temp [210] and you shut it off it will not restart unless it sits for about 20min. Fuel pres. is at 60 pounds. The air inj pump assy and hose assy has been replaced as have the spark plugs. It has 63000 mi. any help or ideas?

MT-2500
09-17-2007, 02:00 PM
What engine?
You need to check the fuel pressure on a cold start up.
It has to have full fuel pressure for it to squirt the injectors on a cold start.
MT

xracer1
09-17-2007, 07:38 PM
It is the 4.3 v6. It has 60lbs of fuel pres at cold start. The problum is after it reaches normal temp and you shut it off it has to sit for about 20min before it will restart.

MT-2500
09-18-2007, 10:19 AM
Fuel pressure specs are 60/66 lbs pressure.
Cold or hot start you should be seeing around 65 lbs on start.

I would put a pressure gauge on it and check pressure cold and hot and running on the road.
Watch for any fast leak downs.
Running on the road or idle the pressure should range 62 to 65 lbs depending on the engine load.

Whe no start check the fuel pressure and for good hot blue spark to all spark plugs.

Do you have any codes or check engine lights?
Do you have a scanner to check sensor readings and fuel trim and tempt readings in the computer?
How are the fuel and air filters?

MT-2500
09-18-2007, 10:24 AM
Guide lines on fuel pressure testing
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

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