pos 1996 jimmy

[pos96jimmy]

i have a 96 jimmy it has fire fuel and turns over but doesnt start

[blazes9395]

That P.O.S......

...need some more info if you want someone to help, did it just stop running, how have you tested for "fire"?. fuel? Was there anything done to it recently?

[pos96jimmy]

it had a new fuel pump installed. new plugs wire etc. my wife drives it .she said it had slowly started to become harder and harder to start untill now where it wont start.i grounded a plug to the frame and had spark.ive had a couple of people tell me maybe the crank sensor or the map sensor. plus i put a new battery in it first.any help would be wonderfull. Thanks

[blazes9395]

My first suggestion would be to get a fuel pressure guage on there and see what kind of fuel pressure you are getting and if its holding the pressure of leaking down. If you have good strong constant spark, then its not your crankshaft sensor, as if that was defective, you would not be getting a spark.

[pos96jimmy]

ive even tried pouring a lil bit of gas down the trottlebody it didnt even backfire sputter or anything.i thought if it was a fuel prob that would atleast tell me.

[MT-2500]

Best to use carb cleaner as a starting aid for fuel delivery problems.
As requested give us some fuel pressure readings?
Got good hot blue spark to all cylinders?

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