Brief story: Uncle gave me a 1994 Honda Accord 4 cylinder
Current issues: carbon fouling ALL plugs and terrible misfire

Hey guys I’ve already replaced the main relay, plugs, wires, cap, and rotor. It seems like I’m running too rich? Any ideas on how else to diagnose this problem? (Check engine light appears to be burnt out and cannot be replaced, therefore I cannot pull codes by bridging the OBD1 connector)

Did a compression test on all cylinders, reading around 160-170 for all.
Could it possibly be a bad distributor not firing? I’ve pulled out the plugs and tested the arc, they all appear fine.

Edit: I can hear the fuel pump priming when ignition is on and also stuck a screwdriver against each injector and can hear clicking sounds so I don’t think all four injects are stuck open

Any help would be great! Thanks

 

If your CEL light does not come on when you first start up your car, I would say to replace the bulb. That way you can actually see the DTCodes and know what is going on with your engine vs randomly throwing parts at it. From what I remember about the CD5 Accord chassis the gauge cluster is relatively easy to remove.


Other than that it could be fuel or fire.... If you have good spark at all 4 plugs I would say to look at your fuel pressure regulator,

With the car running, pinch off the vacuum going to the top of the FP regulator it and the idle should change. If it doesn't, then you know that there is an issue with the regulator. then go from there!

 

thanks for some insight! I took out the instrument cluster and popped open the back white cover, didn’t see a direct bulb for the CEL. Do you know if the bulb is located on the top like shown in the video?

I’ll have to try pinching the fp regulator and see if I get any noticeable changes, however, the car already runs really rough and can’t idle on its own. I would have to accelerate a little just to keep the engine running. Would you accelerate a little and pinch off the vacuum hose to see whether the engine stalls out or not?

 

That is how the FP regulator works, at idle it sees higher vacuum, opens up with less pressure required, and has a lower PSI @ idle. As vacuum is decreased the FP regulator requires a higher fuel pressure to opan, therefore it runs at a higher PSI. SO if your PF regulator is not seeing vacuum at idle it will be running your engine @ the higher fuel pressure than it should be.

Fuel pressure with vacuum at the FPR (idle) - 30-38 PSI with proper vacuum at the fuel pressure regulator.
Fuel pressure with less vacuum at the FPR (30% throttle - WOT) = 38-47 PSI with the fuel pressure regulator's vacuum hose pinched/disconnected.


First thing to check is that you are actually seeing vacuum at the FPR @ idle. With the engine running remove the hose from the FPR and check for vacuum. The idle should rise up due to the fact that you have now created a vacuum leak. After you have verified that there is vacuum at the FPR try plugging the hose back in, let the idle drop back down and then try pinching it off.

 

Okay so I unplugged the vacuum line going into the FPR, confirmed there is vacuum.

However, no idle changes from unplugging the vacuum line, or pinching the vacuum line when it’s plugged into the FPR. Is my FPR just bad and sticking open, letting high pressure fuel spray into the injectors? Sorry this is my first time working with the FPR.

edit: also didn’t see any fuel coming out of the vacuum line when I unplugged it too

 

It seems as though your FPR is not working, It's a good thing that there is no fuel on the vacuum side of the FPR. Currently with the FPR not lifting with vacuum pressure your car is running at a higher fuel pressure than it should be at idle, it is running rich. A new FPR is fairly cheap, I would suggest that you replace it and go from there.