I rarely reach out for help in forums, either i phrased my question wrong or maybe because it was a stupid question. At any rate I will do my best to be concise and specific. Thanks in advance. I literally don't know where else to turn.

2004 Chevy Blazer 4.3 Vortec, 2 wheel drive, 2 door, 220,000 miles

2 yeas ago i put bad gas in my truck and it started to run rough and throw p0300, p0174 codes

I first checked fuel pressure. 45 psi and leaking. So I removed the upper manifold to inspect and replace the regulator.

That did not fix the leak or rough engine or codes. So I bought a MFI injection system from Amazon and installed it and it ran about the same for a week and stopped.

I chose to enroll at the YouTube school of diagnostics. I started by changing the MAP sensor (cheap knock off didn't fit put old back on) then replaced fuel position sensor(AA Ignition not oem) . Then I change the evap purge valve along with the plugs, wires, cap and rotor(plugs, rotor and evap purge valve are delco the rotor is delphi and wires are federal parts).

Then i replaced the coil and module (brand ENA). I replaced both the camshaft and crankshaft sensor with a 4 star Amazon knockoff. (did my research... Lmfao)

I checked the fuel pressure tester. PSI 55 with fast leak. I decided to remove the manifold and check directly for the leak. The new MFI injection body had a crack directly beneath the fuel inlet. So I removed the spider injector again learned how it worked and pulled the injectors out and put them in the old body along with regulator. I put it back together and no more leaks. I have not done an injection pulse test or noid test.

And somwhere in all that YouTube schooled ignorance i replaced the fuel pump because i broke the connection tubes trying to remove it for inspection along with the evap vent solenoid and charcoal canister to clean and inspect.

Now... I got a p0118 code and replaced the coolant temp sensor which had been broken at the connection and reset the codes in the obd2 Torque scanner app. There are no codes now but the check engine light stays on when the key is on engine off.

No fuel leak and pressure is at 55 key on engine off, 65 key on cranking. It has spark at coil and at #2 and #1 plug. The obd2 scanner shows 135 rpm when cranking. I checked #1 cylinder tdc and rotor position pointing at #6. The fuses are good. (side note... A dogear broke off the distributor so to keep the cap tight iwith zip tie.

It turns over good and catches slightly from time to time wanting to start. When I spray carb cleaner in the throttle body it sounds like a backfire hiss every few rotations or so.

I hope this was thorough and easy to understand. I seen some crank no start videos about ground faults and pcm trouble shooting but I dropped out the YouTube diagnostic school for dummies. It cost way to much. So I leave it with you good and skilled gear minded folk.

Again thank you for any information that will point me to the right fix.

 

Sounds like you are out of timing. When you set the timing with #1 cylinder at TDC, was that on the compression or exhaust stroke?

 

On the alternator i turned the nut counter clockwise until pressure built up with my finger on the number 1 cylinder. Then I put a screw driver in the plug hole until it came to the top. I checked the rotor and it was pointing to a mark looked like a 0 or 6 on the base of the the distributor about where the #6 piston would be.


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All you need for an engine to run is compression, good fuel at the right amount, and spark at the right time.

But first please answer how long it has been since it started and ran.

Next I want to see compression check values for all cylinders (no oil), and sharp reasonably close up photos of the business end of the 6 spark plugs. Note if they were wet when removed, and if wet how long it took for them to dry @ temp (no blowing on them)? Also note if there was liquid blowing out of cylinders during start of compression check.

Please provide this info and we can go from there.

 

Thank you for your help. It has been sitting since the first week of September this year. Approx 2 months.

By "business end" i assume you mean a clear photo of the gauge? Or a gauge on a short hose close to the plug hole?

And I haven't done a compression test since I worked on planes in 2001. "no oil" is a type of test equipment or an option for testing i. e. add oil to the equipment?

To complete the rest of your instructions I will need to get a compression tester. I will get back to you as soon as I am done.

 

I suspect that he means the electrodes on the spark plugs and that oil in the cylinders would alter compression numbers, so don't lube 'em up.

 

Yes sir, thank you. I wasn't thinking about that because they are brand new and don't show much. Awesome. Just in time to im heading out there to get it done now.

 

. Yes, electrode end of spark plug. Still need to know if they were wet, and if so how quickly they dry off. Yes, just dry compression with no oil added to cylinders. Should take about 5-6 puffs to max out compression. Throttle should be held wide open during compression test.
Charge the battery up before you start. Do compression test with all spark plugs out.

 

Yes sir, i just did my #1 cyl and the plug was dry. But I took out the fuel pump relay. Is that the correct percedure? That is how i read it in my GM maintenance manual?

I still smell gas come on strong then dissappear. So i am confused a bit. I apologize for asking such elementary questions that im sure are common knowledge. But this is a new area in vehicle maintenance.



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Yes pulling the fuel pump relay and disabling coil is a good idea.