Bought a 1995 F150 today. It is a single cab, short bed, has a 300 straight 6 with a 5 speed manual transmission, and 116K. I absolutely love the little truck! My only concern is that at different times in different gears that it seems to have a studder or stumble while driving. I replaced the plugs, wires, cap, rotor, coil, air filter and cleaned the throttle-body and the idle air control valve, but it still has this stumble. Sometimes it happens in 1st or 2nd gear while taking off, other times I feel it in OD while at cruising speeds. It almost feels like something fuel related because when it happens it feels like running out of fuel. Any ideas? I know I need to change the fuel filter but should I be concerned with the fuel pump? Is there a pump in each tank? If so it happens no matter which tank I use......

-Welder

 

if you have dual tanks there will be one pump in each tank and then another one after them (correct me if im wrong) and then since you said both tanks it will most likely be the 3rd pump...i would try the fuel filter its on a couple bucks and it could do the trick i did it just cause on my 95 when i bought it...or you could try some injector cleaner or if you have the knowledge tools and time you could pull em out and clean em up nice

 

I'm pretty sure the 95 just has a pump in each tank. Not likely both would give same symptom.
You do need to change the fuel filter since you have no idea when it was done last.
I would pull the codes. That is almost always the first place to start. The check engine light does not need to be on to have some problem codes saved. The engine needs to be up to temp, or you will get several codes that are not real problems. The instructions that came with my cheapy code reader are to get the engine hot and then just prior to pulling the codes, hold it at about 1500 rpms for 2 mintues. I think this is to get the exhaust nice and hot also.
Since you have recently tuned it up, It might be interesting to pull the codes, then clear them, and go for a drive. This makes the computer relearn the settings for the engine. I usually pull them again after a 30 minute drive. Any codes that are present in both tests are of true codes and not old stored problems.
Based of the description of your stumble, I would also check the timing. The distributor wiring harness has a small jumper plug in it. This plug, called the spout connector, must be removed before to check the timing, and reinstalled when you are done. If you forget to put it back, the truck will start fine and drive like it has no power. Don't ask how I know this.
Good luck Frank

 

You don't have a third fuel pump on the frame rail. My '88 does, but I believe they went with just in-tank pumps as of '89 or shortly thereafter, well before '95.

Check out the truck's battery. Is it either recently installed, or so old it may have recently gone dead? The reason I ask is as follows:

I don't know if your truck is Mass Air, but on my Speed Density '88 300 cu. in., the ECM will go back to default fuel/spark mapping, if the battery has been disconnected for any length of time. I was told my a Ford tech (and friend) that on older trucks, the ECM has made adjustments for wear, to improve how the truck runs, but when you disconnect the battery, and it reverts back to the "default fuel/ignition mapping," those original settings may not be exactly what your truck needs, and it can result in drivebability problems, similar to the stumbling at lower speeds, that you describe. I don't have an automatic, so I can comment on what that might be like, when it stumbles.

When I was a Ford Service Writer, we used to advise the customer that things like this can require the vehicle to run through a number of "drive cycles" (sometimes 50 or more!) before the ECM will reset itself.

I have experienced stumbling in the lower gears, (under about 1,700 RPM) as a result of battery changes. Mercedes techs used to connect a 9 volt battery to the cars, when changing batteries, to preserve the ECM's settings, and avoid this situation. Not sure if Ford recommends such a procedure or not.

Just a theory, as you asked for "Any ideas." I hope others will feel free to correct any mistakes/assumptions I have made here, for the greater good.

Good luck and congrats on your new purchase--sounds like a very sweet little truck--I LOVE the Big Six (engine)!

 

I would consider testing the TPS (Throttle Position Sensor) and running some sea foam in the tanks.

 

buy a manual.

what brand and type of spark plugs, wires and cap/rotor?

cleaning the iac only helps once in a while.

if in doubt replace it.

 

Congrats on the new purchase, you are going to love that 300ci. Good luck fixing the studder.

 

there ya have it i knew at some point they had 3 pumps but i didnt know they discontinued that.

yeah man i used to be a v8 guy but i bought my 300 and i love it...

 

Ok,

So I ran some seafoam, replaced the IACV, replaced battery(was 8 years old), and I still felt the stumble, so I had a mechanic friend check the codes and it said bad TPS and Spout connector. So I replaced the TPS and the stumble at highway speeds is better but when first taking off it is still rough! I checked the Spout for continuity and it shows to have continuity so could it still be bad? Truck does seem a little low on power so I think it needs timing and from what I know the spout plays a role in this. I see where the spout ties into some sort of module on the driver's inner fenderwell. Looks like 6 wires plug into it. My question is wether that module could be bad and if so why the code reader didn't say so?....or did it by saying bad spout connector?

Thanks for all the help guys!
-Welder