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CRX ECODiesel Ram
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Discussion Starter #1
car is an 89 crx si engine is rebuilt running about 12:1 compression. p06 street tuned with crome. has been working fine for months.

08 civic injectors, cheap chinese fpr, walbro 255 lph hp pump, stock rail drilled and tapped for a gauge. pumkp was put in new about 2 years ago along with a new fuel tank due to rust issues, fuel filter replaced twice at that time.
also had bcpr6e spark plugs.

under acceleration most noticeable at 75% or higher throttle above 4k rpm it would intermittently lose power, kind of buck then surge. did not happen while cruising.

started by changing the plugs to bkr7e. that helped a little in smoothing everything out. the stock plugs had about 5 on them and were looking worn (designed for the 9:1 original engine...).

then started seeing my fuel pressure was not consistent, going both high and low, so i bought an aem remote mount regulator, and the hardware to mount it and get fuel through it. pulled the rail tapped it, ran the new lines and hooked the regulator up. at time i thought i had gotten all shavings out of the rail.
went to test drive, and the same intermittent power loss. under no load free revving the fuel pressure was dropping into the 40s before bouncing back to where i had it set at 54 psi.

also noticed one injector not flowing fuel, pulled it, cleaned it and solved that, then had a second do it as well. cleaned it out and then a 3rd did it. so im assuming that i did NOT clean out well enough. injectors are likely to be sent out for cleaning professionally at Injector RX in Houston.

next dropped the fuel tank. the sock on the pump was dark, had lots of little particulate looking items in it.

so im thinking i either have a clogged line or a pump not able to maintain flow under pressure. the way i see it...i can get a new sock and put it back together and go from there. i can get a new pump and put it in and go from there, or i can run a new fuel line and filter and possibly take on pump options.

what would you do?
 

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Definitely send the injectors out.

I'd flush the fuel lines out, drop the tank and clean it, make sure the pump isn't clogged, and put a new sock on it.

You could have gotten some crap at the gas station, just filling up. Do you always go to the same station, or at least stay with a 'brand'? You may need to try out a different station.
 

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Meat Popsicle
91 CRX Si
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I know this doesn't help you now but you should have just installed a fuel pressure gauge at the fuel filter outlet so you didn't have to tap anything. If it were me, I would:

-Make sure your tank is at least 1/3 full
-Set your fuel pressure back to 38-40 PSI at idle
-Have your injectors cleaned/flowed

When my tank is less than 1/3, ill see intermittent fluctuating fuel pressure at idle because of the way the walbro pump sock sits in the tank.

There is no need to have your fuel pressure that high.

Injectors would be my last thought but I wouldn't be a bad idea to have the peace of mind to know that they're all flowing the same.
 

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I would try a new fuel filter, my car would do the same thing. I thought no way its the filter because I had replaced it about 8 months before it started. I tried new plugs, injectors, fuel pump, got an AEM regulator and rail and it still did the same thing. Finally tried a new fuel filter and ran like a champ.
 

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CRX ECODiesel Ram
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Discussion Starter #6
Definitely send the injectors out.

I'd flush the fuel lines out, drop the tank and clean it, make sure the pump isn't clogged, and put a new sock on it.

You could have gotten some crap at the gas station, just filling up. Do you always go to the same station, or at least stay with a 'brand'? You may need to try out a different station.

injectors will go out, they are used can i know they sat for years before I got them.

I rotate between several brands and stations, still doesn't mean that there isn't crap in all of them of course.

The tank is 3/4 full right now, and the fuel I have flowed into cups has been clear so far.
 

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Discussion Starter #7
I know this doesn't help you now but you should have just installed a fuel pressure gauge at the fuel filter outlet so you didn't have to tap anything. If it were me, I would:

-Make sure your tank is at least 1/3 full
-Set your fuel pressure back to 38-40 PSI at idle
-Have your injectors cleaned/flowed

When my tank is less than 1/3, ill see intermittent fluctuating fuel pressure at idle because of the way the walbro pump sock sits in the tank.

There is no need to have your fuel pressure that high.

Injectors would be my last thought but I wouldn't be a bad idea to have the peace of mind to know that they're all flowing the same.
tank is 3/4 full.
that pressure is too low for this style injector, they are spec'd at 47-54 psi and designed to have their best spray pattern at that pressure. will not be lowering the pressure below spec. plus the car was tuned at that pressure and worked fine for months and close to 5k miles.
 

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()*#$(*$
93 Legend L Coupe.
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AEM FPRs are the most unreliable pieces of junk out there. I would rather run a B&M Chinese knock off pop-top regulator than an AEM unit. That doesn't mean yours has failed, but it wild be highly suspicious.

It sounds like your injectors are gummed up. Are you using stock fuel filters?
 

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CRX ECODiesel Ram
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Discussion Starter #10
yes stock filter. do you have a recommendation for a better filter?

the aem unit is brand new, and the prior unit was a very chinese ebay one that I had laying around. Initially i thought its plastic diaphragm was failing as I had reset fuel pressure at least once every 10 days for the past month due to it not maintaining set pressure.

been doing some reading on classic car forums about flushing fuel lines, I am not going to bother doing that. This line is 25+ years old, and it sat for about 5 years at one point with fuel in the system and lots of rust, many of these guys dealing with situation like that are saying just replace the line rather than fight with flushing and never knowing if you got it all out.

I opened up a fuel line at the rail and at the filter and the initial fuel pump prime produced about 1.5-2 oz of fuel, while at the pump it produced about 4 oz of fuel during the same prime. That leads me to believe I have restrictions in the stock line, and will like get a length of something comparable to aeroquip aqp socketless hose with an inline filter...
 

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you have something worthwhile to add or just feel like making worthless statements?
Your a funny little internet warrior arent you? Well, lets see. You jacked up your base fuel pressure, but didnt bother to think about what that might do. You installed something half @$$ and expected it to work perfectly. Your crying about having to do work on your car and just want some one else to figure it out for you.

Sorry, but I can actually fix this for you as I do this for a living. But I choose not to help some one that will not help themselves.

Since I am feeling nice today, I'll start you off on how you diagnose the concern you have, other then picking up a book and reading... Oh and trying. Return to stock fuel system outside of the pump, using another cars full fuel engine bay systems components.... And then try to fix your car. Its easy, least thats what people on the internet tell me. :innocent:
 

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CRX ECODiesel Ram
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Discussion Starter #12
I set my base fuel pressure based SPECIFICALLY on Honda service manual specification for this injector. Maybe you are not aware that different injector technology actually operates ideally on different fuel pressure. Want to learn something new? Honda actually changed the required fuel pressure based on the technology that went into the injectors, pintle versus disc, and 1 hole versus 4 and 6 hole. The specification for pressure for an injector is based on more than just required fuel flow, it is also based on things like spray pattern which impacts power, efficiency and emissions.



If I follow your "advice" can you guarantee that I will not run super lean and grenade my engine? I am personally a little concerned about running low pressure lower flow injectors and computer that are spec'd for a 9:1 compression engine as compared to a 12.5:1 compression engine. That just doesn't seem to bright to me, but what do I know I don't "do this for a living."


Do I really want someone else to "figure it out" for me? Or perhaps maybe I just want some input from others who are not looking at this up close. Sometimes we miss things that are obvious, especially when we are focused on individual details...such as a 25 year old fuel line that is likely full of varnish which was completely overlooked as source of a problem that can alter fuel flow and pressure.
 

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For starters, its good that you recongnized the dirty fuel sock. Thats a known problem that can be fixed. Clean the tank, get new filters and sock (make sure its the correct sock) and then see if anything changes.

As for the FP battle.....Id stick with the injector's recommended pressure myself.

:popcorn:
 

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Discussion Starter #14
Just for kicks i backflushed the fuel feed line with about a pint of acetone. lots of black flakes of varnish coming out as well as smaller reddish particulate matter as well.
I did not realize that crx fuel lines ran inside the car, I was hoping to get some fuel line and run a new feed line from the pump to the filter.

I sent the injectors off for cleaning today, and ordered a second fuel pump(I am also working on a 1993 prelude which is getting a new drivetrain and needs a fuel pump and tank) and two install kits which have new socks.

I may go ahead and pull both fuel lines and replace them as I do NOT trust them at this point. The banjo fittings had reddish black build up inside of them as well.
 
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