95 F150 Can't Find It's Horses

1995 F150 Eddie Bauer 5.0 4x4 Dual Fuel Tanks

Old Bertha has a lot of miles on her and I'm fixing the problems as they come. She is not my DD, so I have time.

Latest problem is a major lack in power accompanied by a check engine light that comes on and off. It does not flash, but is sometimes on and sometimes off. What I mean by lack in power is that when I floor the truck, SOMETIMES it feels like I'm just softly touching the gass. She will gently shift gears as if that were the case. Other times, I floor her and unleash the beast breaking the tires loose as I shift into second gear.

A few weeks ago I was driving down the highway having trouble getting up to 60 mph on a flat surface, then 20 minutes later I'm going up a steep grade accelerating past 70 mph like it was a walk in the park. There is NO bogging or kicking of any sort.

The only thing I have actually done is replace the fuel filter. It was gross and rusty.
There are two fuel tanks and the truck acts the same way on both tanks which eliminates those two fuel pumps. I believe there are no more fuel pumps. One thought is there could be an obstruction around the tank selection switch point, but I kind of doubt that.

What other things could this be? I'm probably going to run up and get a fuel pressure gauge tool next week. What other areas should I be looking into?

TPS?

Yeaaaaah, last one that failed caused a slight bog and actually shut the vehicle down, but I can see how that could cause the problem. I'm going to check mine out when I get a chance. This is a momentary problem, so maybe it's something I can smack around. Thanks for the suggestion.

Frame mounted pump?

Can't find info on the frame mounted pump, so I assumed it didn't exist. From what I'm reading now, the high pressure frame mounted pump was dropped in about 1990 and they use a high pressure pump in each tank.

My other thought is a clogged cat

Check to see what code is causing the CEL

Clogged cat is a possibility. A very good possibility. Thought of the TPS and vacuum system, but not that. I need to redo the exhaust anyway. I haven't gotten a chance to run by the store to check the CEL. I'm not too familiar with the OBDI systems. Does the light have to be on to read it?

TPS is a good start.

Plug wires? Almost sounds like they're old/bad and arcing to ground intermittently.

The first thing to do with any ford drivability problem is give the maf a thorough cleaning with carb cleaner.

I would sexond the plug wires. My Z had the same issue and it was caused by plug wires that were going out.

Ok. Clean throttle body, replace plug wires, and test TPS. I'll also Clean up the distributor and put a new cap on it. When I drive through deep water, she gets water in there. In fact, she seems worse on wet days. Coincidence?!

Worse in wet weather means its time for plugs, wires, cap, and rotor.

Does it have a TFI ignition module mounted on the distributor? Usually this part works 100% or not at all... But if you are having ignition problems, this needs looked at too...

95% sure you've got the dreaded bad DPFE. The over the part counter replacements plain suck. Some are nice enough to tell you they suck on the paper inside the box say the high and low signal ranges are outside fords OEM spec.... then why is this a replacement part?

gearheadmb wrote: Worse in wet weather means its time for plugs, wires, cap, and rotor.

I'm not 100% sure if it really is or not. The last two times I've driven her, it has been wet and the problem has gotten worse, so I'll be tearing apart the wires and distributor.

In reply to 44Dwarf:

The main problem doesn't feel electrical, so I wouldn't be surprised if it comes back to sensors. Are you saying buy from a dealer or preapare for suckness?

44Dwarf wrote: 95% sure you've got the dreaded bad DPFE.

Agree, your symptoms sound exactly like when the DPFE went on my Focus. Also, you mentioned wet conditions which is where the problems come from. On the Focus for some years it was mounted where water could get into it. Ford changed the mounting to a remote mount on the firewall to avoid the water problems.

http://www.focushacks.com/mod/DPFE_Sensor_and_EGR_Information

Toward the bottom of the page, there are a couple temporary hacks to bypass it the DPFE. The resulting performance and codes you get will point you toward the answer. The solenoid itself is a common failure as well, but it does sound like you have a bad DPFE. Try your cheap/free fixes first. If not, see above.

When I finally solved it in my truck yes I got a ford OEM part. It doesn't feel electrical cause its in the egr recirc that's killing your power.

www.fordtrucks.com

Well, I'm going to go ahead and read more through some of the links, but here is where I sit.

Disconnecting the vacuum from the EGR makes the truck run much better. Replaced the EGR Control Switch (No DPFE) with no result. Removed the EGR and gave her a suck and she seems to react to suction. Replaced the EGR Position Sensor with no result towards the performance, but now the check engine light STAYS on.

I don't feel like throwing any more parts at her, but if anyone has any suggestions, please post.

Next step will be pulling the vacuum lines and inspecting them inch-by-inch.

The code readers are super cheap. Could help somewhat.

Code reader is your friend.

Some auto parts stores will pull the codes for free.