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1999 Subaru Outback Gas Problem

Hey Car Talk!

I need some help with my Subaru. I bought this car about 5 months ago. When we bought it, there was a problem with the transmission. Soon after, we realized that the whole transmission would have to go. Luckily, my dad used to be a mechanic, and we replaced it. Ever since, it’s ran PERFECTLY… until now.

Lately is having problems idling, accelerating, and keeping a constant speed. When you’re driving, it’ll run fine, then just totally bog down, RPMs and all. (Usually just going 5-30 MPH). It’ll slow down about ten miles per hour, and then just suddenly jolt back up to normal. The same thing happens at all, it’ll bog down, and then ten seconds later the computer will kick the RPMs to about 2000. It’s really intermintent, but here’s some consistencies: it’ll always do that within a couple minutes of driving, and never at highway speeds (except when you’re at a stand still and then accelerate). Usually it’s a real slow gradual kind of bog, but there have been a couple of times when it violently jerks. The check engine light does NOT/and is NOT on at any time.

So, we’ve also tried some cheap fixes. We replaced the spark plugs. My dad said they all looked great, and that they might even be running a little lean. We replaced the fuel filter. We replaced the spark plug wires. We have also added fuel injector cleaner in to the gas as well. The car needed it, so we also replaced the battery. None of these things have effected the performance at all. It still does it. It has gotten to the point where every time you start it up, whether hot or col, it’ll do it.

So, the only thing we can think of is that gas just isn’t getting to the engine like it should. Could it be the fuel pump? Is there any way to test this? Is there an easy way to get to the fuel pump to see if it’s blocked/clogged by something? Online, the fuel pump is around $300. Is this about right? If that’s what the problem is, we’ll do it, but if we’re unsure, I don’t want to fork over that kind of money for no reason. What else can we test!!??

Thanks so much for your help in advanced!

Steven Wilcox

1999 Subaru Outback Limited - 160,000 miles

If you’re dad’s a mechanic I’m pretty surprised that he hasn’t checked the fuel pressure - by all means that is what needs to be done. If he has to have him rig a fuel pressure gauge that can be watched as the car drives. (Putting a pressure gauge on it is the best way to get a read on the pump).

Another thing to do is put a vacuum gauge on it and check for exhaust restrictions - something like a clogged catalytic converter, or maybe that potato that one of your enemies stuck in there.

Hey, thanks so much for your reply!!!

Well, he used to be a mechanic, a while back, but still knows a TON!

How would you recommend going about installing a pressure gauge? How much do they cost? Are they easy to install?

My dad knows for sure that it isn’t a catalytic converter. He said if that were the case, it would have this problem all the time, and not be intermittent.

One think we read was about “vacuum” hoses. We messed with a couple of hoses attached to the diaphragh, which didn’t change anything, but later we learned that if there is liquid in on of those hoses, its a sign that you have a bad fuel pressure regulator. My dad said that he does remember one feeling like there was still liquid in one. (None poured out, but he did suck air through the hoses). Could this be the case? How difficult is it to get to the fuel pressure regulator? Is it a part with the fuel pump? Do you have to replace the fuel pump to replace the regulator?

Again, thanks for your help!! :slight_smile: