A few weeks back my mark started stumbling at part throttle. It would momentarily cut out and come back. I had an occasional blip one day and then I wasn't sure if I was going to get home from work the next day.
My first guess was the fuel pump, the car has 175k on it, it wasn't out of the question. So the car started stumbling so bad one day I was able to make it continue stumbling in the garage while I had it in gear and my foot on the throttle a little. I hooked up a fuel pressure gauge expecting to see the pressure jumping around. It was rock solid.
Side note: Plugs and wires are less than a year old, crank and cam position sensor are about 5 years old (<20k miles), and the car ran perfectly smooth and performed well before this.
Based on this test my next guess was the coils which are also original. I swapped out from coils from my parts stash from a 94. I put them on and immediately the car ran perfect. A little over a week later it started to stumble again. I figured since these were old coils they may have just been on their last legs. It looked like the plastic/epoxy resin was breaking down on these coils I swapped in. I bought a new pair and put them on, the car ran perfect for a few days again.
Now yesterday it started again on my way home from work, so needles to say I don't think the problem is with the coils.
I put the code scanner on it and pulled some codes from the stored memory:
524- Low Speed Fuel Pump Circuit Open
542- Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits
211- Ignition PIP signal was erratic or missing - Ignition Systems (crank sensor failure?)
I ordered a fuel pressure test kit that will allow me to actually drive with it on since it has a much longer house and a 90 degree fitting for the rail.
So what do you guys think, fuel pump likely the cause even though it was showing rock solid pressure stalling the car up in gear while it was skipping?
I hate to drop the exhaust and fuel tank and throw parts at it unless I'm sure that is the problem....
My first guess was the fuel pump, the car has 175k on it, it wasn't out of the question. So the car started stumbling so bad one day I was able to make it continue stumbling in the garage while I had it in gear and my foot on the throttle a little. I hooked up a fuel pressure gauge expecting to see the pressure jumping around. It was rock solid.
Side note: Plugs and wires are less than a year old, crank and cam position sensor are about 5 years old (<20k miles), and the car ran perfectly smooth and performed well before this.
Based on this test my next guess was the coils which are also original. I swapped out from coils from my parts stash from a 94. I put them on and immediately the car ran perfect. A little over a week later it started to stumble again. I figured since these were old coils they may have just been on their last legs. It looked like the plastic/epoxy resin was breaking down on these coils I swapped in. I bought a new pair and put them on, the car ran perfect for a few days again.
Now yesterday it started again on my way home from work, so needles to say I don't think the problem is with the coils.
I put the code scanner on it and pulled some codes from the stored memory:
524- Low Speed Fuel Pump Circuit Open
542- Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits
211- Ignition PIP signal was erratic or missing - Ignition Systems (crank sensor failure?)
I ordered a fuel pressure test kit that will allow me to actually drive with it on since it has a much longer house and a 90 degree fitting for the rail.
So what do you guys think, fuel pump likely the cause even though it was showing rock solid pressure stalling the car up in gear while it was skipping?
I hate to drop the exhaust and fuel tank and throw parts at it unless I'm sure that is the problem....