98 blazer wont start when cold/damp

[billindelicato]

For some reason the truck just refuses to turn over...i can hear the fuel pump and have tested the lines for pressure but cannot get it to go. I have pulled the distributor and cleaned all contacts and added some dielectric grease to keep out any moisture but it still wont start...just replaced the battery...pulled/replaced fuel filter...still no go!!! any ideas??? It seems to start just fine if the weather is pretty decent but being up here in buffalo...that's only in the month of july

[MT-2500]

Originally Posted by billindelicato

For some reason the truck just refuses to turn over...i can hear the fuel pump and have tested the lines for pressure but cannot get it to go. I have pulled the distributor and cleaned all contacts and added some dielectric grease to keep out any moisture but it still wont start...just replaced the battery...pulled/replaced fuel filter...still no go!!! any ideas??? It seems to start just fine if the weather is pretty decent but being up here in buffalo...that's only in the month of july

Is engine cranking good?

Just pressure on line is not good to go.

You need 64-65 lbs of fuel pressutre on a cold start to squirt injectores cold.

What are you cold start fuel pressure readings?

Or all of them?

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.