So I've got a 2001 Chevy Blazer LT with the standard 4.3L. Nothing special. Except it wont start lol. It started about a yr ago anytime it rained it wouldn't start. So i did my research (mostly on here). From what i read i changed my plugs, plug wires (even pumped em full of dielectric grease), Brand new AC Delco distributor cap, and a new crankshaft positioning sensor. I've set the vehicle to TDC and made sure the distributor matched. At one point my grandfather said it may be my catalytic converter so I even cut the exhaust to let it breath a little. Nothing so far has worked. I have noticed though while trying to start it I'll smell excessive fuel coming from the TB. (I also pulled the TB about 2 weeks ago and gave it a thorough cleaning). I bought a fuel pressure tester today. The pressure at the schrader valve sits right at about 54 (which i know is just barely under "limits"). It does seem to leak down slowly. Whats a good measurement of time to go by for the leakdown test? Could it possibly be the fuel pressure regulator? I have no clue anymore. I got so frustrated with it today I almost sold it for $300. Its been a rough couple months but i want my badass blazer running again! Any thoughts on the issue would be greatly appreciated! OH AND THE BEST PART ITS NOT THROWING ANY CODES!

 

If the injector spider is original, then fuel pressure is critical as a minimum pressure needs to be present in order to overcome the spring in each injector. If the injector spider has been upgraded to the later style with electrical wires going down to each injector, then they will still open even if pressure is less than optimal (in my opinion would still start and run with your 54 psi pressure). My personal experience with my brand new upgraded Delco spider is that it is regulated to 58 psi during 2 second pulse when key is first turned on (engine off) (a little less than in the sticky).

However, no start when raining seems like an ignition or electrical problem (unless fuel pump or fuel pump controls stop working for some reason).

As long as you still have a non-intermittent no-start I would recommend doing the following in this order. You might want to verify no-start after each segment.

Start by checking for nice strong blue spark at the output of your coil. If present this will check your crank sensor, primary ignition controls, and the coil itself. If present, then do the same at the end of one or more spark plug wires. Spark should be able to jump a 1/4" gap at the end of a plug wire. If not, figure out where the spark is going. If OK, move on.

Check for fuel injector pulses at the plenum harness connector while cranking. If none, figure out why. If OK, move on

Pull an easy spark plug to get at and check compression on a cylinder. Is the spark plug wet with gasoline? Is the spark plug carboned up? If battery is charged up, compression should be well above 80psi when cranking with other plugs in. if OK, move on. If below 80psi, you have bigger problems to deal with.

Check your dead-end fuel pressure per the sticky. If not OK - replace the pump. If OK, move on.

Pull the plenum cover and look at the injection spider. Do you see that it has been leaking and spraying gas somewhere? Is it old style or new style? If it has been leaking or is still old style, replace it. If not, replace it anyway as you have verified everything else.

 

Are you sure you set TDC on the COMPRESSION stroke? Common mistake to set TDC out of phase on the exhaust stroke.

 

@lesmyer I have checked spark. Everything's good there. The only thing I haven't checked is compression or pulled the plenum. I've either checked or replaced everything else.
@rockp2 I'm dead certain it was done correctly. Number 1 cylinder was at the very bottom.

 

Sam, no offense intended, but I really don't think you have done what I asked. Remember that how you have diagnosed in the past has not worked out for you - so please don't simply tell me that everything is good for multiple tests and jump to the end. If you had spark, then why did you put a crank sensor and a bunch of ignition parts on it?

Please do exactly what I asked in the order I described and report results for each step. Be specific about how you did the tests. How did you check the injector circuits and what was the result? Did you read the sticky on fuel pressure? If so, please tell me what the dead-ended fuel pressure was. If you don't understand how to do the tests, just ask. We are here to help but you have to do your part.

 

Hold on, doesn't TDC put the piston at the very top just before downward travel begins? (Admittedly, I just skimmed the post so I may have missed something...)

 

@lesmyer I replaced all the ignition components as a tuneup. I did the fuel pressure test and it had 58psi on initial. It leaked more than 5 psi in less than 20 min. I just removed the plenum and the 3,1,5 cylinders are washed. Fuel pressure regulator?

 

Sam, you still haven't done what I asked and are trying to jump to a conclusion based on inadequate and conflicting test info. I'm sorry but I don't seem to be able to help you.

 

Correct, #1 should be at the top on the compression stroke to be in phase TDC with the rotor pointing at the little "6" on the distributor.