Hi, new to the forum, hope I can get some help,
I installed a new manifold gasket after there was a water leak into the oil. Cleaned manifold well, marked distributor and reinstalled, did an oil change and coolant change, took pictures and re hooked up everything best I could. It ran with low rpm and also the rpm would lope, thus I though IAC valve, when driving and would stall when hot, cleaned EGR valve, did a vacuum test that read ok then today changed IAC valve, ran it for 20 minutes, then it won’t start a few hours later. Swapped out IAC valve for old one and still won’t start. Hoping you intelligent problem solvers could lend me some insight, distributor perhaps? Thank you for any input, I will reply to any questions or input

 

So it cranks but won't start?

Assuming yes then its a top down drill. First figure out if its:

ignition
fuel
Timing
Mechanical
ECM/pwr/gnd/sensors
security issues

Then drill down once the offending subject is identified. I would start with double checking all connectors and wires where you worked then test spark at a few plugs and fuel pressure per the sticky. If those are OK we go from there.

Also, any codes?

This might help:

https://blazerforum.com/forum/2nd-ge...rticle-103750/


George

 

No codes, or check engine light, simply cranks without starting. Very strange in that I meticulously followed this forums hints on changing manifold and still ran into trouble, gut feeling tells me it’s a fuel or fuel injector issue. was thinking it might be a wait of a few hours until it starts if it’s a flooding issue, so will read up the thread link you sent and try and see if it will start in the morning,
thanks for the reply!

 

If you suspect that your engine is flooded, crank it with the gas pedal fully depressed. That shuts off the fuel injectors in "flood clear" mode.

George

 

Interesting strategy to know for flooding… well it started this morning and idled fine in driveway, all electrical connectors checked over and hooked up properly. Going to pick up fuel testing kit and begin deducing problems. Seems to be an issue of getting hot and stalling, with low and loping idle. May go down the line and clean spider assembly, it’s a 1998 blazer 4.3 vortec.

 

Yeah you test each top level area, even better if you can do that one it’s running crappy. When you find one that doesn’t look right like spark or fuel pressure then drill down to find the cause.

Sounds like you need to get a fuel pressure gauge for that part so in the meantime pull two or three spark plug wires at the plugs while it’s running giving them a path to ground and look for 1 inch of strong blue spark that beats with a consistent cadence. If you have a scanner that can read live data then look for codes and start with fuel trims. After that we can look at sensor values. Since the distributor was involved do you have the ability to read CMP retard?


George

 

An update—- was a bit impetuous and installed new spark plugs, one wire broke so I got new wires too. Noticed the distributor cap was loose and ‘popped’ off during installation of wires, and one hole in plastic where screw fastens it down was worn out. Tightened it down again and zap strapped it tight. Put gas and fuel injector cleaner in. Ran it just now for a while around town - no more ‘loping’ rpms or stalling. The rpms drop to about 500-600 when at stop signs, red lights though. Overall consistent and strong though. Will keep checking in days to come on problems…