1991 Legacy runs jerky on highway

[zwempa]

Hi all

 

I have a 1991 Legacy 1.8 GL Petrol 4x4, great car except for my problems...

 

The problem is as follows.

The car sometimes runs rough and jerky and I lose power when running at highway speed and accelerating slightly or accelerating to get on the highway or going uphill.

The problem usually arises when accelerating at 2000rpm up 3-4000rpm in 3rd or 4th gear. But also when maintaining highway speed for a while.

When the problem starts it doesnt help to decrease or increase the throtle or shift gears, the engine runs jerky until I stop ,turn the engine off and on again, then the problem is gone for a while, but sometimes comes back immediately when I try to accelerate again. The problem never starts at low RPMs and it doesnt seem to matter if the engine is warm or cold. Also, I havent been able to reproduce the problem by just reving it in neutral

Does anybody have a clue???

I havent been able to find anybody that had the same problem!

Thanks for any ideas!

[Legacy777]

Is the check engine light coming on? You may want to try pulling the codes and see if any codes are stored. Instructions on how to pull the codes are on my site.

 

Have you done a routine tune-up recently: wires, plugs, pcv valve, air filter, fuel filter, etc? You may want to try that if you don't find any codes.

[zwempa]

I forgot to mention my car has a carburator.

I recently have change the airfilter in my endevours to try to fix this problem. The old filter was very dirty but unortunately the problem remains.

I checked the flow of fuel from the fuel pump, I estimate that it delivers something like 60 liters per hour from the hose just before the carburator (after fuel filters), but I havent changed the fuel filter.

 

I havent seen the "check engine light come on at any time".

I followed the instructions on your site (excellent site by the way) tried (and tried again) to find the cables for the ECU but no luck.

My car is right hand drive, there may be a different location for the cables!? I will give it another try again in daylight.

 

My next thing will be to check plugs ,wires and possibly the distributor.

 

Could this problem be caused by the carburator, there are a few things that can go wrong in there. I will hold off for a while before I take out the carb though.

 

I am not sure if my car has a pcv (pressure control valve??) as it has a carburated engine.

 

Thanks for the tips, any other ideas are also welcome.

I ' ll keep posting on my "progres"

thanks!

[stevemeeters]

I'd try the fuel filter.

[Legacy777]

Being that your car is carburated and has a distributor, that brings a lot more things into play that could be causing it.

 

Unfortunately, I'm not super familar with subaru engines that are carburated. I'd probably start with the fuel filter, maybe spray some carb cleaner in there. One of the jets might be plugged. You should probably check the distributer cap & rotor for wear, as well as check ignition timing.

 

PCV = positive crankcase valve. I doubt this would cause your problem though.

[zwempa]

Hi everyone!!

I finally got the car running properly! And for you who guessed fuel filter, you guessed right. I really should have changed that in the first place but I didnt come around to it, I thought the flow of the gas was alright when I checked it but I guess the pressure must havebeen to low (a pressure gauge would have been handy).

Anyway, I got a new fuel filter (paper type) for around 3dollars and that hit the spot!

 

Thanks everyone for your help and support