Jp7

iTrader: (2)

I recently bought a 2000 Honda Civic EX 1.6 SOHC Sedan to try and build a reliable winter car. I bought it with 74,500 miles on it. When I got the car, I only drove it a total of about 20 miles before putting it up on my hoist and doing everything that I felt I needed too.

I put on a new timing belt, water pump, adjusted the intake/exhaust valves, changed power steering pump & leaking rack, changed fuel filter, radiator and put in a set of new injectors. Besides the fact that the power steering rack was leaking bad and shot most of this was just for maintenance because the car is 18 years old. Radiator was really crusty at the bottom and leaking a little.

I noticed that when the car sat for a little while and cooled off the engine would not catch immediately when I cranked it. Sometimes it would try and catch and stumble for a second and then start. I looked at scan data and my ECT sensor and IAT seem correct with what environment temperatures are. I thought that my fuel pressure may had been bleeding off into my return line or back through the check valve in the fuel pump. I bought one of the permanent mount fuel pressure gauges and installed it on the output side of the fuel filter, which is mounted on the firewall. Priming the system with the original Honda pump I see 32-35psi at a prime. The fuel pressure did leak down though- after about 10 or 15 minutes you could see it fall a few PSI, and then after about an hour or 90 minutes it went down to zero or close to zero. I blocked off the return line, and measured for the same leakdown- which I saw the same results. I bought a brand new bosch fuel pump, and I picked up a new regulator (more just as a maintenance item as it was cheap)- installed both of those. Fuel pressure is about the same after a prime but it actually looks like to me that the leakdown is a little faster than before- maybe taking 45 minutes or so.

I don't think this is a leaking injector problem. My fuel trims are slightly positive (+7%). I also can't smell raw fuel in the intake manifold when I remove the airbox and stick my nose in there. I also removed the vacuum line from the fuel pressure regulator and smelled the side that goes to the manifold and I don't really smell gas like it is leaking into the intake manifold. Don't forget- the injectors are brand new also.

I don't think this is a fuel pressure regulator "seat leaking" problem. I clamped the return line going back to the tank and watched the pressure decay just like it does when it is not clamped. Also- the fuel pressure regulator is new. If the diaphragm was torn it would be leaking into the intake manifold and I don't see that either. Plus my trims would be negative. They are positive.

I suppose it could be a bad fuel pump check valve- but my fuel pump is brand new. I bought a decent one (bosch) too.

The fuel lines under this car ARE in rough shape. They look pretty rusted and will need to be replaced soon. I actually called honda looking to get new lines for the car (I was really surprised because they actually SELL these still!) but I am not sure how hard they will be to install without removing the subframe in the front. I do have a lift in my garage but I don't want to remove the subframe. Sure I could have an externally leaking line- but I don't smell gas. I suppose I could have a pinhole leak but I can't imagine it leaking where I wouldn't smell it. I need to put the car on the hoist and look more carefully.

I also want to find a soft spot with rubber hose between the fuel filter and the fuel pump that I can block off and see if the pressure still drops. I am trying to remember if the lines coming right off of the tank are rubber or plastic before they turn into the metal portion. I can't remember.

I want to emphasize that this is not a "long" crank time- it just is a little longer than what a new car would have. It sorta "half catches" when it should start- and I get a stumble and then it starts. I haven't tested it in warm weather yet but my garage has a furnace set at 45F over night and this does not help.

I'm almost wondering if this much bleed down is normal and I'm on the wrong track. 2 of my other cars have fuel pressure gauges permanently mounted- but they have electrical sending units that won't allow the gauge to work until they are keyed on- so I can't really watch the fuel pressure decay like I can with this mechanical gauge permanently mounted under the hood of the civic.

ezone

This does not sound unusual to me


The system needs to retain residual pressure that is high enough to avoid boiling fuel in the line (vapor lock) for a period of time sufficient for the engine to cool down.
As the engine compartment temperature drops, so does the residual fuel pressure requirement
Once it's below the temperature at which the fuel boils, the residual pressure can be zero

Jp7

iTrader: (2)

Some cars hold fuel pressure for a really really long time thats why I ask. This is my first Honda. On my Evo ix it vapor locks when it is in the 90s or higher after being parked if I go in a store and come out in a few minutes- but this is on a highly modified fuel system. I am searching for a cause of my "longer than instant" crank time.

GolNat

iTrader: (7)

Does it start better if you prime the system first? Turn key to ACC, then off, back to ACC, off then start the car?

ezone

I didn't find a real spec on residual pressure so I just gave a general rule of thumb

Jp7

iTrader: (2)

I think the purge valve might be sticking open. I'm going to check that. Yesterday I took apart the IAC and it wasn't that bad but I cleaned it out and now it is super clean as a whistle.

I want to emphasize that this isn't a long crank time, it just dosen't crank like a brand new car. It just bugs me.

Colin42

Well it's not a brand new car... it's almost 20 years old.
Maybe post a video of how it cranks and we can tell you if it's normal or not

Jp7

iTrader: (2)

It's not normal- I know this, I just need to find the cause so I can fix it. This is not something like is the case on my Evo where I have 1800cc monster injectors and dialing them in for starting is difficult. That I know is hard to start. These are rinky dink stock 200cc injectors with a factory engine, ecu, no mods....

Colin42

So what is it doing? Be descriptive, or post a video

Jp7

iTrader: (2)

I tried to get a video and I swear it starts perfect every time I film.

This was sitting over night, probably about 8 hours. Car was indoors in a heated garage with a 45F temperature when I filmed this.

This was a particularly bad start. She must have not known I was filming.

https://drive.google.com/open?id=1h_...29jjrpxEQYcl3a

Colin42

Ok, seems like it's cranking like my girlfriend's car when it's low on gas. If you leave the key on for a few seconds is it better? Or if you cycle the key on and off a couple times before starting is it better?

Jp7

iTrader: (2)

I need to do consistent testing trying that to give you any useful answer. When I prime it, if I go under the hood and look at my fuel pressure gauge it does jump up to about 35psi. I have been not doing multiple primes.

I did hook up my smoke machine and I smoke tested the entire intake- it is really tight. No leaks that I could find at all.

GolNat

iTrader: (7)

Does it start better when you do this? Regardless of fuel pressure or anything else.

Jp7

iTrader: (2)

I haven't "done this" enough times to give you an answer I'm confident of. It's on my "to-do" list.

ezone

This alone can cause startup issues. Is it your issue? I can't tell that from here.....but
Winter blend fuel is designed (blended) so engines start well in cold weather.
Unseasonably warm weather (and heated garages) can cause starting issues simply because the winter fuel in the tank was blended for easy starting in the expected local ambient temperatures, not your heated garage

Jp7

iTrader: (2)

I kind of doubt it in this case. I have 4 cars now and none of the other ones have this same problem. I start them all once every 2 weeks religiously and let them idle until the thermostats open and the fans come on.

This morning I started the civic up after sitting 4 straight days with no activity and BANG fired right up. I only keep the thermostats at 45f, that's not that warm.

Results outside vary too. Sometimes BANG it fires right up, sometimes not. The start in the film was particularly bad though.

Something else is going on and I will get to the bottom of it. I have other issues that I am addressing. Every piece of rubber under the car (bushings) is not to my standard. I have replacements that I need to install. I also have an issue with water getting in the blower motor that I have not eliminated yet. These are higher priority to me right now.

Jp7

iTrader: (2)

I have been trying to start it consistently with multiple "primes" by cycling the key and I think now I have enough data to say it's not helping.

I do not think my problem is a lack of fuel pressure.

Jp7

iTrader: (2)

Update- I think one of my new injectors may be leaking during sitting. Today when I started the car it stumbled bad, and I did so with the driver door open. I ran out of the car the second I let off the key and you could really smell the exhaust like raw fuel. I think this may be fouling out the plug creating my stumbles. I need to swap back the OEM injectors and see if it still does it.

Jp7

iTrader: (2)

OEM injectors swapped back in. I think I fixed my problem. Need more data to confirm for sure.