Mallonpaulj

Hi guys! New to the board so I will keep this short and sweet. 93 5.0 LX conv. Smooth idle ans strong accelleration up to approx 4K rpm then very bad stumble and engine miss.
Changed fuel filter and it got much better (past 5k before stumble) but that lasted only a day. Back to previous problem. Changed filter again yesterday with some slight improvement.
Could this be the fuel pump just not up to snuff? Pressure Regulator too restrictive? You would never know there was a problem till you let it run out through the gears. 111k on the car.

Thanks!!

mdvaldosta

Do a fuel pressure test, or install a fuel pressure gauge and go for a drive. ALot of times ignition problems cause higher rpm misses, and I had a camero (POS) that had a fuel pump go south and it would try to stall BELOW 4k, but over that it ran ok (the engine was helping to suck in fuel at the higher rpm's). Some tell tale signs are a loud fuel pump. But really it could be in your ignition system - so you may wanna find out for sure before you start changing parts.

Mallonpaulj

Thanks for the fast response. I did suspect an ignition problem so I replaced the cap, rotor, wires, plugs (twice but not with platimum version). Ran somewhat better as you would expect but not noticably better till I removed the original eqmt filter that appeared to have been in there from day one. It ran much better for a couple of hours then seemed to load back up.
I will try the fuel pressure gauge to see what I have with the engine idling. Not sure if I can rig one to view as I accelerate.
The pump is clearly running when I turn the key. Really does not seem overly noisy but this is my first Mustang. Similar to a GM in tank pump in loudness....audible hum while running.

roundman

Could be you got some bad gas with too much water in it also. try adding some dry gas to the tank and see if this helps some.

Mallonpaulj

Hi,

Thanks for the response. I think gas is okay. I have had the issue for some weeks now...several different tanks of gas and brands. I thought the same since I got a load of watered gas in NJ when I was stationed there in the Army. I run ethanol here in IL (89 octane) and have had no issue with a prelude, Accord and Cherokee.

Paul