jdb168

My 98 Cobra is not happy. A few months ago, I bled the brake fluid/put squeal dampener on the back of the front brake pads, and changed the fuel filter. I'd been having brake squeal issues, and random engine stalls (when stopping). I also noticed, while checking out the spark plugs, that the wells were full of oil. Well, after that round of maintenance, the stall issues got even worse. I guessed that one of two things might have happened...

1) I might have installed the fuel filter backwards (I was very careful about this though...)
2) I might be having misfires from taking out three of the plug wires and reattaching them with a small amount of oil at the mate with the plug.

But I didn't get a misfire code... And the filter is on correctly.

So, I decided to go in and change the valve cover and plug well gaskets anyway, since the leakage was clearly pretty bad. I also replaced the plugs and wires to be safe (I'd already bought a new set of each). At the same time, I addressed my IMRC codes by cleaning out the IMRC and intake thoroughly, as per the PDF guide the SVT Mustang Cobra club of Houston posted online.

Well, no more IMRC codes yet, but I am still having the same stall issues. Anybody have any ideas what this could be? My friend Oscar and I think that they're most likely related to the fuel pump or to an electrical issue. Here's exactly what happened last time and this time when I tried driving the car around.

First time (before valve cover and IMRC job): Was fine for about three minutes until I tried to take the on-ramp to my local highway. The engine stalled while I was shifting from 3 to 4 around a bend. I had to restart the engine in motion, and keep driving, but the car started to buck really badly. I got back off the highway, and it stalled as I came to a stop. It bucked the whole way back to my house.

This time (after all recent work): The engine was fine idling for 5 minutes at a time, but the moment I pulled the car out of the driveway and tried to drive up hill the bucking came right back, and the car stalled. I pushed it back into my driveway.

So, I'm a bit stumped. I'd think that a fuel pump issue would show while idling... but it's only showing while the car is in motion. Could the pump still be to blame, and could the difference in fuel required for moving vs. for idling be the reason that it only stalls while in motion? Or can anyone suggest what else might be causing this bucking???

Sorry for the long post. I hope it makes some sense. This issue has been a bit of a nightmare.

Thanks,
Jon

1fstblckgt

Got me too... I hope someone can help you with this. Sorry i cant.

trickdriller

Could your fuel lines be cloged? Have you run out of gas at any point when owning the car?

1fstblckgt

I started thinking the same thing right after i posted the first time... What about your fuel injectors? what about the fuel lines? coil packs?

jdb168

Awesome! Thanks for the reponses. It's nice to know that there are a couple of other brains thinking this issue over.

When I removed the injectors and fuel rail, I didn't think to test for clogs. I can probably take them out again quite easily and try to purge them with solvent of some sort or pressurized gas (water I assume will corrode the lines). I've never run out of gas, though... however, I've only had this car for a few months. The previous owner, from what I can gather, was not incredibly familiar with the car's workings, or all that careful about upkeeping it. So it's possible he might have run out of gas at some point...

Fuel injectors... I suppose I could test those outside the car by applying a voltage (I assume 12V DC, but I'll check) to them and monitoring the streams. I did, a few months ago before all this occured, run a fuel system cleaning additive through that I hoped would address anything like this...

My friend and I also thought about coil packs. I guess we're hoping that's not the issue, since they're not cheap items But, hey, if that's the problem, that's what you have to address!

So, anyway, please let me know if you have any more insights. I think I may also try having a mobile mechanic come by for an hour or two to look at the car to diagnose the problem...

Mark99GT

That sounds like a fuel pump issue to me. The car uses the least amount of fuel at idle, which may be why it idles ok. Id getthe fuel pressure tested.

My girlfriend had a similar problemwith her car (not a mustang). Had the same symptoms you do and it turned out to be the fuel pump.

jdb168

I'll certainly give the fuel pressure test a shot. I think my roommate and I may be able to do this...

And, fyi, I've checked my firing order, and it's all fine. Shucks... I wish it were something that simple.

racer02GTstang

you say oil on the plugs... should be your valve cover gaskets to tell you the truth... alot of dohc cars we get in at work like audi and bmw.... they have the studder and crappy running and its the valve cover gaskets are bad so they leak oil down into where the plugs are since the plugs go down the center of the valve cover.

racer02GTstang

crap... says you changed them already...


well then..... check all connections and make sure all vaccum lines are on right. that is a good place to start. then check the fuel pressure.

jdb168

OK, I'll give that a shot, too. I had to replace one vacuum hose since it was starting to crack, so maybe there are others in the same condition. Thanks for the advice.