20 replies to this topic

[Bubba]

The only precise mixture adjustment on these cars is the low speed circuit- which just controls the mixture at idle and fairly low rpms. You can adjust the linkage that opens the tiny butterfly on the carb (this makes the super rich mixture that goes to the plug) and that will richen things up a bit (I did it once- power was definitely improved, but I closed it back since I was wanting mileage).

If you hear spark knock and the engine runs hot, then you can be concerned about burning valves or a piston.

If you go through with this, definitely be prepared to readjust ignition timing.

[mickcrx]

Thanks for your help. I have a monkey on my back before I decide to do a complete carb overhall. Ever since you mentioned the spark plug knock and the shift light thing, I am eager to figure this out.

The car bucks on acceleration in each gear and seems to sputter and lack power. Idle is around 750 with a bit of a shake in motor and irratic slight rpm needle up and down. At times, after a quick rev of the peddle in neutral, the rpm will shoot to high rpm, then the rpm needle will give a quick dive down quickly to an almost stalling state, then go back to 750 rpm. This issue has been driving me nuts for a few months trying to figure it out. The car defidently runs rich, because there is lots of black soot on the tailpipe, and the EGR valve is sooty after I cleaned it 1000 miles ago. Also, the exhaust/cat clanks and clicks as if it is getting too hot. I do get a spark plug knock/chatter on acceleration (as if there is bad gas, but I use the good stuff). I pulled the spark plugs inwhich I replaced 1000 miles ago and they are brown and ashy on the tips as if they are getting too hot. The car is getting low to mid 30's for mpg, which is low for my HF. I did a compression test and all 4 cylinders read at 180. I replaced spark plugs, PCV valve, Fuel filters, a new vacuum advance control on the dizzy, took the carb off and took just the choke plate part of the carb off and cleaned all the holes possible in reach on the entire two halves of the carb with wires and carb cleaner. I was told by several mechanics that they did a vac leak test and there is none. The shift light does not come on while driving. It only comes on when I turn the key on just before starting the car. How would I adjust the fuel air mixture on the carb so it don't run rich? Where is the adjusting screw? The fuel level in the glass window on the side. of the carb is just below dead center (about 1/16 of an inch). This issue is so aggrivating, because I know there is a cure. I have run out of ideas. I am trying to figure this out before I drop a couple hundred into a reman carb. I thought of a devac, but maybe this is not my issue. My two main concerns are: 1) STOP THE BUCKING 2) MAKE THE CAR RUN LEANER Thank you much, Mick

Edited by mickcrx, 12 July 2012 - 01:25 AM.

[Bubba]

The soot indicates running rich. Have you checked the fuel level in the carb? Look at the sight glass on the driver's side of the carb. The fuel level should be in exact center of the clear window. A bad o-ring in the float seat (the top section of the carb) can cause this. It happened to my civic- the idle quality was bad and it would blow some black smoke when reving it up off idle.

The bucking could be a spark problem (try to swap in a spare distributor if you have one) or you might have a bad oxygen sensor which is causing the whole emissions system to lean it out too much.

Before I devaced my 87 CRX HF, the shift light would work halfway correctly, even though it also bucked under hard acceleration. Maybe you can find an HF service manual so you can try to figure out the self diagnostic mode on this car (I believe that there is one). If I recall correctly- the 5 wire wide band oxygen sensors for the HF are $250 and are hard to find (they are a smaller diameter than any other oxygen sensor I have seen).

[mickcrx]

bubba i just took off the float assembly and the orings are shot. i appreciate your input. i will order dome o-rings (god knows where to order). Maybe i have to just order an entire carb rebuild kit to just get those o-rings. i will see. thank you much.

Update: Just ordered the last in stock beck arnley kit on rockauto for $29.80. Will see what happens. Thank you, Mick have a good weekend

Edited by mickcrx, 13 July 2012 - 06:40 PM.

[mickcrx]

replaced the orings on float adjust valve. still no shift light while driving. the light only comes on when i turn the key on

[Bubba]

With a good SIL light bulb, but no SIL light when driving, I am thinking that this is a computer/emissions system/sensor issue. Try the suggestions I left in the other thread first. If the carb is spotless inside and fuel delivery checks out, there are no vac leaks- and you always have good spark, then you could either start replacing sensors, or do the devac.

Edited by Bubba, 20 July 2012 - 07:48 AM.