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View Full Version : Engine hesitation/bogging issue - stock KA


OverBoost
06-14-2010, 07:05 AM
I have already thoroughly searched and cant find any threads related to my issue.

Yesterday, I was driving along and came to a stop light. All of a sudden, I step on the gas to go forward and the car starts bucking almost like the clutch wasnt engaging properly. However I noticed when I pushed the gas it would only rev to 2-3K and then the engine revs would drop and jump up, it would continue this cycle even with the gas pedal pushed all the way to the floor, even with transmission in neutral. No matter how hard you push the gas, the engine will just rev up and fall down, rev up and fall down, continually. I could only get the car up to about 20 mph.

Strangely, when I turned the car off for a few minutes and restarted it, it would drive normally for a couple minutes and then start doing it all over again. No strange colored smoke from exhaust, but it did smell a little unusual (but not like fuel).

Complete stock KA24DE in a 91 S13, just rebuilt with 500 miles on the rebuild and had been running fine up until this. New Parts: plugs, plug wires, distributor/cap, pcv rebuilt injectors, fuel filter. Rebuilt trans, new clutch/trans parts. Short ram intake. Stock emissions. Fuel pump about 3-4 years old. Car has 190K miles.

I have a feeling its the fuel pressure regulator starting to go out or even fuel pump, because I did not replace them during the rebuild. It could be another part of the emissions (EGR) or even the MAF, including vacuum hoses. But then why would it work for a couple minutes after turning engine off and then restarting it?

ANY input would be greatly appreciated.

I LUV MY S13
06-14-2010, 10:06 PM
its definitely a part of the fuel system, either pump or filter

OverBoost
06-16-2010, 09:58 AM
Filter is new, but i guess its possible its clogged up. Pump seems to prime ok, however the car did have trouble starting that day, maybe the pump is starting to go?

Checked all the spark plugs today and they look normal, no fouling or fuel on them. The weather was very hot above 95 F, on the day it happened. So I guess vapor lock is *possible* but that usually happens on non-fuel injected cars. I'm still leaning towards FPR.

Any other ideas?