Ok so normally I hate forums, mainly because the answer isnt always "check the timing". But I'm stumped, like really stumped, I know this car, it's a 2003 civic si, the ep3. And it ran fine. It's got 210,000 miles on the k20a3 engine. So, now it wont start, it began as a hesitant start. It would turn over a few extra times and then fire. it gives me no codes and no check engine light, just turns over and over and over with the occasional spudder from trying to start. I have good parts kicking around so I tried solving the issue with known good, plugs, coils, fuses. I even went as far as changing the alternator, ecm and ignition. all good. before this it never went into limp mode and drove like a brand new car, when it did finally start. Any ideas?

 

Fuel pump and/or it has jumped time at the crank.

 

Fuel pump sounds, pressure at the rail, spark plugs get wet after I turn it over. If it jumped time, it would have run funny or bent a valve and the compression is perfect. Also it has a chain so it would more likely break instead of jumping a tooth

 

back to basics i suppose:

-fuel: fresh, clean fuel in the tank, good pressure at the rail, injectors pulsing when trying to start.
-air: no abnormal restrictions to air flow (clogged filter, plugged cat. converter/muffler), the correct amount of air (vacuum leak would allow too much, mechanical failure... not enough?)
-spark: verify at the plug (bright blue arc with the plug grounded while trying to start). check all four coils. double check engine grounds for clean secure connection. look for signs of damage or corrosion on the coil wire connectors.
-compression/timing: don't know that I've checked this on a K-series before... but i'm sure there is a procedure out there somewhere!

if a spray of starting fluid or brake parts cleaner into the TB helps any, then focus on fuel supply.
cap any non-essential vacuum lines. if that helps focus on air.
obviously if one or more coil fails to spark replace with known good used or new and try to start.

(I know you said you had check some of this already, just giving an quasi-exhaustive list for others who may stumble on the info in the future.)

 

I have checked like 90% of what you listed off. But I have to give you credit, that may be the most helpful thing I've ever read on a forum.

 

If my list is as complete as I hope it is, you only have 10% left to check before you find the root cause. if not, we both stand to learn something when you figure it out.

 

one thing as a time. My next step would be to cap the fuel return and put a gauge on the fuel rail, have to be sure you're getting the right amount of fuel.

 

It is a return-less fuel system.

 

I was wondering that as I posted. Still stick a gauge on it and see what it’s doing.

 

I just bought a non starting 02 SiR (Canada) and I'm going thru the exact non start issues as you. Ether into throttle body will not even start it, so I've ordered a new crankshaft position sensor. 🤔😬🍺

 

Maybe this will help someone in the future... I went through a similar nightmare with another car. It turned out it was the third catalytic converter that was clogged. That specific one would not give a check engine light. Prior to that, I had one of the first cats clog and give me the code. I replaced that cat, which would allow the car would start but was in limp mode. It didn't give me any codes. I replaced pretty much everything you can imagine, and started replacing the same items again with OEM parts. Until one late night I saw someone mention similar to what I am writing, removed the exhaust and saw the issue was resolved, ordered a new third cat and fixed it.

 

So I've done all kinds of things to fix this car, and nothing worked. I was ready to give up, and for ***** and giggles I pulled out the plugs and swapped them with the old plugs it had when I first suspected it was an issue with spark. Now it runs. Idk how all 4 plugs could foul at once, and idk how old fouled plugs could make it start. But I've changed so many parts that i dont know exactly what the issue was.