Hey there I'm really struggling I would appreciate any help.

I replaced the head gasket and intake manifold gaskets on my 3400 motor.

The van has extended cranks before starting and and often will not start unless I give it a shot of ether. Once running it seems fine although a rough idle. During extended cranks I have confirmed to have spark.

• New coil packs, one was bad.
• New fuel pressure regulator, the old one was leaking.
• Fuel pump pressure is about 48 PSI with engine on and running.
• New spark plugs and wires.
• I rechecked the injectors, all around 13 ohms and spray when given power. Not the best mist more of a stream but ok.
• Thoroughly cleaned throttle body and replaced IAC valve.
• Throttle sensor tests good.
• Cleaned MAF sensor
• Crank sensor output appears good.
• Replaced fuel filter and gas cap

Any direction at this point would be appreciated, I just want the van to start consistently.

 

Some similar issues in this thread may add insight: https://chevroletforum.com/forum/ven...t-start-72454/ also https://chevroletforum.com/forum/ven...e-issue-66190/

My own (2001 Venture) rough running engine troubles ended up being the 24X crank sensor.

 

I appreciate it, looks like there is a lot to look through.

If I had an oscilloscope maybe I could do a 'real' test of the 24x crank sensor. I used a guide at this site: https://troubleshootmyvehicle.com/gm...crank-sensor-1

At this point I may just swap it out.

...

Other theory: I replaced the IAC and heard it sort of self adjust on start up. That said, I think they can be manually adjusted? At the least, I just want to check this.

I built a smoke tester and found no intake leaks.


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Did you get to the bottom of this issue? Was it, perhaps, a vacuum leak? Just wondering because I'm doing head gaskets on a Montana and want to be forewarned if something similar ends up happening.
Thanks...