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Discussion Starter #1
Lately the car has been putting out a lot of fuel fumes while idle. My cabin air intake seems to suck it right out of the bay and pump it into my face. My nose leads me to either the fuel filter (which looks perfectly fine) or the EVAP canister (which has everything attached except the vacuum).

My build is a 95 Civic Hatch CX chassis with a D16Y8 edelbrock turbo kit (with the exception of a Disco Potato- GT28RS), vitara pistons, stock cam, supertech springs, port and polish, blah blah. Basically the engine should be comfortable making 300hp. Right now I'm sitting at ~175hp because my exhaust is choking the hell out of the engine, but that's another topic.

I've been told that it doesn't matter whether the EVAP canister is attached or not. Lately I'm beginning to think there might be a pressure buildup in the canister, but I don't understand the mechanics of it, and how lack of vacuum would affect it. I'm all for getting better mileage, and if that will help I'll put it back together with a new solenoid (old one broke during build).

Question one: Can the EVAP canister have a pressure buildup without vacuum?


The second part is a bit simpler. I have a stock FPR on the fuel rail and the tuner that worked on my car said I had to rev the engine every time I started it, otherwise it would stall. He couldn't figure out why it stalled. This sounds to me like the compression chamber is getting flooded by the Walbro 300lph pump when it primes. I know there was a mod (TheOldOne) that intended to fix that, but in the rush of moving across states I never was able to get it done.

Question two: Could the pump be flooding the compression chamber, causing the engine to stall while starting? Is there another possibility?
 

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Sounds like the stock fpr can't handle the 300lph pump (some of the integra fpr have better results) and your smellin the bent fumes from the engine.
What catch can set up do you have?
 

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Discussion Starter #6 (Edited)
Sorry guys, got busy for a few days. I have no wideband, just oil pressure and vacuum gauge. The car is tuned on Neptune. It will start fine, but if I don't rev for the first twenty seconds it will stall.

The injectors are Siemens Deka 60lb/hr Fuel Injectors Zetec/SVT/ST170.



My catch can setup doesn't vent to atmo, it uses vacuum from the intake and drains to the block fitting:

 

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Discussion Starter #8
Thanks Guest.

I took the FPR off today and drilled a relief hole in it (Endyn DIY). Holy $%@ the difference is big. My idle is really smooth, and for some reason the response is a lot snappier. Not sure about the fumes yet, just drove it to the gas station and back.

It still won't idle on start without me revving it for about twenty seconds. One thing I forgot to mention is that if the engine is warmed up and I turn it off for a few minutes, it can be started and will idle without any problems.

I won't be able to take it to a tuner anytime soon, so I'm trying to fix what I can for the moment. I'm broke and the quarter is about to begin. College=no time no life.
 

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I can't see from your pic but do you have a FITV or IACV?

Having the EVAP can with no vacuum is why you smell fumes, obd1 cans have a fresh air vent on the bottom that is allowing the fumes to escape. If you don't plan to use the EVAP system then delete it.
 

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Discussion Starter #10
Ah! Thank you! That explains it.

I'm using the Intake Air Control Valve. The Edelbrock intake manifold has it mounted in a diagonally downward facing position, so it's difficult to even get at it with the camera.

None the less:

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Now what I really need to know is:

Will the car get better mileage with the EVAP system?

and

Is the ECU function of operating the "Purge Cut Solenoid Valve" affected by the Neptune tune or part of the hardwired chip functions on the PCB?
 

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You wont get noticeable better gas mileage but you are wasting gas venting it to atmo(thou it is a small amount).

EVAP would work as long as it wasn't used for something else in the tune(like boost PWM)
 
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Discussion Starter #12 (Edited)
Ah, good. That's a $130 part I can skip. I've chipped the board for PWM and have all the wiring ready, so I'll go ahead and remove the EVAP system. Thanks for the detailed explanation!
 

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Discussion Starter #13
Shit. I spoke too soon. Reading on the removal process, it seems I need to keep the tank line open. Wouldn't that vent fumes into the cabin just the same as it's doing now?

Also, I'm using A11 (Exhaust Gas Recirculation control solenoid--which didn't exist on my chassis) on the ECU for PWM signal. EVAP solenoid is listed as A20. Is there another reason PWM and EVAP can't get along?
 

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I've vented the line from the tank in the engine bay and pulled all the evap parts for years and I never smelled fuel.
 

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Shit. I spoke too soon. Reading on the removal process, it seems I need to keep the tank line open. Wouldn't that vent fumes into the cabin just the same as it's doing now?

Also, I'm using A11 (Exhaust Gas Recirculation control solenoid--which didn't exist on my chassis) on the ECU for PWM signal. EVAP solenoid is listed as A20. Is there another reason PWM and EVAP can't get along?
The EVAP system can work just fine with boost PWM as long as the EVAP circuit wasn't used for boost PWM. You say EGR was used on your ecu so EVAP will still work.
 

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You most likely need to adjust your cold start enrichment.
 
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