i have a 1994 subaru legacy wagon with an automatic tranny, usually when i first try to get on the freeway and really push it to get to freeway speed or even just faster than 45 it gets to speed then starts to run really rough untill the engin just dies. after this i wait for maybe five to ten minutes and it starts right back up. now going up hills that are not really steep at all just constant it can not hold its speed even if on cc. it drops around ten mph then when it gets back to flat it speeds up again. now i have done basic tune up things except the 02 sensor, such as pcv, oil regularly, belts, plug wires, does anyone have any ideas by chance because this is a real downer because otherwise i love the car! any help would be really awesome thanks.

Have you tried a new fuel filter? It's under the bonnet.

Yes ditto, fuel filter if you haven't done it lately. Those conditions you described are when the engine is going to be demanding the most fuel and it might not be getting enough if that is restricted.

 

Don't think '94 has EGR but fuel filter is in same spot:

thanks for the replys, i wish it was but yes i have replaced it and no such luck any other ideas?

How's your MAF? When those things go flaky they can cause a lot of issues. To rule out fuel issues, you could tape a fuel pressure gauge outside the windshield and then see what it is reading when it starts to act up.

ha sorry i dont know what maf stands for :/ what does it mean?

Edited May 7, 200916 yr by seth3030

MAF is mass air flow (sensor). It's in the plastic intake snorkus tube thing right after the air filter. I have heard on here that while the vehicle is idling, if you tap gently the top of the maf with the butt of a screwdriver and the engine stumbles that the MAF is faulty. The MAF tells the ECU how much air the engine is aspirating so it knows how much corresponding fuel is needed. If it is getting a bad signal from the MAF, it will be adding the wrong amount of fuel and then ovbiously the engine no run so good.

oh ok thanks a bunch i am going home this weekend and will see. in the mean time any other possible things if that is not it

Does this have a ignition module by the firewall (i think it does)? the next time it dies check for spark. If you have no spark it can be that module. Things like the crank sensor can be tested with a analog multimeter while the engine turns.

 

Ignition module/amplifier can drive you nuts trying to diagnose it. If you can get a used one throw it in and see what happens.

 

 

nipper

ok thanks! any other things by chance

I'd tend to suspect the fuel supply still. You could check the flow rate and the pressure of the fuel. To do it properly you need a pressure gauge but you might get some idea about the pressure by squeezing a fuel hose as someone turns the key on. You should be able to feel the hose bulge slightly. Perhaps you could compare it with another car if there is one handy? To test the flow take a hose off the fuel filter's outlet and fit another piece going into a bottle, now get someone to turn the key on and the fuel should come out as a full diameter squirt with no bubbles or dribbling.

 

If the fuel seems to be in good supply and too have a good pressure(fourty pounds or so), then I'd suspect an electronic component playing up. You should check for trouble codes.

Edited May 7, 200916 yr by Log1call

also when it dies it usually only does this once on a long trip then it is fine, but it does still struggle up hills. i dont know if that matters or not.

thanks again

I'd tend to suspect the fuel supply still. You could check the flow rate and the pressure of the fuel. To do it properly you need a pressure gauge but you might get some idea about the pressure by squeezing a fuel hose as someone turns the key on. You should be able to feel the hose bulge slightly. Perhaps you could compare it with another car if there is one handy? To test the flow take a hose off the fuel filter's outlet and fit another piece going into a bottle, now get someone to turn the key on and the fuel should come out as a full diameter squirt with no bubbles or dribbling.

 

If the fuel seems to be in good supply and too have a good pressure(fourty pounds or so), then I'd suspect an electronic component playing up. You should check for trouble codes.

 

I also think this is a fuel supply problem, Have you heard any strange noise from the back of your car? When my fuel pump went out it was making noise before it finally quit altogether.

My pump has never played up but apparently they can sometimes make noises before they die, other times not.

 

Best test for the fuel pump is to test it's flow and it's pressure.