Diagnose my Civic no start
 

I know it's not a classy thread like the new MR2 but I'm out of ideas...

2000 Civic EX. Intermittent no start. Died while driving today. Crank, no start, fuel pump primes, has spark, previously tested no fuel injector "spark" but the main relay has been replaced. No codes. Been fighting this for months

New parts: most of the distributor (Sparks fine), plugs, wires, fuel filter, main relay, crank sensor, used ECM.

Any ideas?

Sounds to me like the fuel pump dying.

Some what simple fix. At lest that's my guess.

Pump primes, pressure tested previously but not in this instance

Yeah a failing fuel pump can prime itself, but it can't keep it running after a while.

There any way to test it short of replacing and hoping it works? The problem is intermittent so that seems unlikely. Every time I work on it the car will run for a couple weeks then die again.

I'm sure there is a tool out there.
Most common is with super duper scan tool with real time analysis.

I don't have anything that fancy but I wouldn't feel bad about taking it somewhere if I thought it would work. Will show the necessary information in a car this old that won't start to begin with?

Well, if you are ok removing it for a bench test, you could put it in a bucket of gas hook up some test tube with a nozzle to add some pressure to the output and run it for a bit, but that might be more trouble than it's worth.

Could it also be a grounding problem?

I could certainly do that. I don't have a way to test the pressure though. I thought it was grounds too but that is a big no, unless it's a ground somewhere outside the engine bay.

Removing the engine wire harness currently to inspect for damage.

When it's having an issue are there any codes?

To me this actually sounds like a bad ECM but you already tried that. Had an accord fail exactly the same.

Did you replace the igniter when you did the dist parts?

No codes. Igniter, coil, rotor, and cap were all replaced. ECM was a "tested good" eBay unit. It's possible it's failing but seems unlikely it would fail exactly like my original one. I can switch them out again if I need to

If the car died while driving then that sounds like fuel cut or electrical. The only thing you haven't replaced is the fuel pump and fuel pressure regulator. You could attempt to diagnose those.


It would be nice to understand how this intermittent problem manifests and resolves. Had you had intermittent problems starting it then it died while driving and since then it hasn't started, or is it still intermittent, in that, it had problems starting then recently died while driving and now it is driving, but still having intermittent problems starting? What was it like when it had problems starting? Was it not cranking; or was it cranking, but it was a dry crank; or was it hiccupping/choking like it wanted to start, but was low on air or fuel or the spark wasn't hitting all cylinders evenly? When it died while driving, was it during acceleration or cruising or idling? Did it just cut out and all the lights went to startup or did it lose power and/or bog out then die?

Dry crank, no sputter at all. Hasn't started since it died while driving.

Previous intermittent no start: crank, no sputter. When it finally did start, it was like nothing had ever happened. Wouldn't even know it had been"broken". Drove fine, parked fine, may or may not start next time I try to drive it.

I checked fuel pressure a while back during a no start and it checked fine on fuel pump prime. I don't own a gauge so I never checked any other time.

When it died, engine shut down at cruise. Power APPEARED to be constant but if everything blinked off for half a second I probably couldn't have noticed (no radio or headlights etc to indicate power failure). It was running, then off. No sputter or loss in torque/horsepower. Just off.

I have not retested fuel injectors for pulse since I replaced the main relay or crank sensor

This sounds like it is all electrical. The bitch of it is diagnosing.


If you crank the motor with a pulled spark plug and see it sparking, and if you have replaced everything in that category then you know you are good. What do the spark plugs look like? Are they dry or soaked with fuel?


If you have fuel delivery then it should hiccup at minimal. I don't know if spraying some fuel in the intake manifold like spraying fuel down a carburetor to help get it going would be worth a try. If it was an individual injector that was the problem then it seems like it would hiccup as well, but you are having a dry crank. If there is a failure on the injector side then it would have to be further upstream and not at individual injectors unless they all got fried or failed at the same time--unlikely. Could you use a multimeter to make sure you have power going to your fuel injectors? If not then work backwards until you find power.

I haven't checked the plugs for soakage this time around. Went straight to electrical since I already replaced the main relay (supplies power to injectors and pump) which presumably fixed the lack of pulse to the injectors (previous no start)

If they are soaked then you know you have some fuel, so it is probably spark. If they are dry then you probably have a fuel issue.


Could the relay have failed again? Could a grounded wire from the relay change be disconnected/loose? A multimeter could really help with demonstrating basic power to these areas.

The relay "could" have failed again but it's unlikely. When I get the wire harness inspected for damage and hooked back up I'll check the injectors for power again

Just throwing this out there, sorry if you mentioned this already but did you test the battery voltage and made sure your battery terminal is not corroded? I had a BMW that had a similar issue in the past, fixed it by simply cleaning the terminal connecting points of corrosion.

Yeah that's all good

Checked engine wire harness today. No apparent damage anywhere. Post on the alternator broke off (of course) so now I ordered one of those. If it runs when that's in, I'll go until it dies again. Otherwise I'll replace the fuel pump and see what happens

The alternator only charges the battery, but you should be able to drive for three miles with no alternator, so I don’t think that would fix your issue.

I would pull a spark plug and have someone turn over the motor and check for spark. If that is good then I would pull the fuel rail feed line, get a bucket and a hose and test for fuel output. If you lack output then check the line going to the fuel pressure regulator. If no output, and you said you replaced the fuel filter already, then consider the fuel pump. You can pull the pump and bench test it in a bucket or just replace it.

Fuel, compression and spark. The basics should be easily diagnosed.

I know the alternator went fix it. I went to test without it yesterday but I had a blown fuse too so I called it a night. I know the pump flows, at least it did because it generated pressure and coughed gas all over my engine bay when I was testing a while back. If it's reliably putting out enough pressure is the question.. So I guess in that, it could be the regulator or the pump. I'll check spark again just to be sure it's still there

If all a person has to do to get an engine to start to fire up is spray a mist of fuel down some carburetors then any fuel delivery should be enough to have the engine sputter, at minimum. If you are having a dry crank then there is zero spark, zero compression and/or zero fuel.

If you think you have fuel delivery then buy a $35 endoscope on Amazon and put it down your intake manifold to verify the injectors are firing if you don’t want to pull them to bench test them. And definitely pull a spark plug and turn over the motor to check for firing. Check it to see if it is soaked or dry too after attempting to start the car.

During previous tests for the same symptoms, it turned over on starter fluid

If it turned over, meaning it sputtered when making a few combustion strokes then that means your spark is probably fine. It is likely fuel delivery then. This could be an electrical failure at the fuel injectors, a fpr regulator failure or a fuel pump failure.

Seems to be what we are down too, assuming the previous testing still applies. I'll go through everything again when I get the chance

Bad gas?

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Put the wiring harness back in yesterday after inspecting for damage. Car started. So either there was a bad connection somewhere or it's done with it's episode and will die again in 2 weeks. Stay tuned

......figured it out.....its a honda....

Usually this is the PGMFI relay to the right of the glove box;

https://www.ericthecarguy.com/faq/so...relay-failures

I'd take apart the one you have and diagnose it.

Went thru 3 aftermarket ones, none worked. Got a Honda Relay which worked for a while. No difference from my stock one. Resoldered my stock one too