Okay. So I've been around this forum site a lot but only recently registered an account. Anyways, I have a 1994 f250 460 7.5l engine, and e4od tranny. About a week ago I was ascending a rather steep hill that goes out of town and I felt one small hesitation and I thought it was weird. About a mile down the road on flat ground it started running poorly, like it was running out of gas. I had gas in both tanks so I flipped the switch with no change. The problem has progressively gotten worse too. I've tried a fuel pressure regulator, both pumps sound strong and are loud when priming. I have yet to test fuel pressure but when I release fuel from the rail there's pretty good pressure behind it. Anyway. I did some other investigations and I was leaning over the front clip listening to the engine and I heard ticking noises. I disconnected the IAC valve so the rpms would fall and I located a bad ignition coil plug wire and I also replaced the ignition coil as parts of the plug itself corroded into a powder. Replaced ignition coil and wire, ICM, MAP sensor, and fuel pressure regulator with no change. Vacuum hose from throttle body to MAP sensor is good. I have a hill that I have to go up when getting on the highway and I can't even get to 30 mph by the time I'm at the top because it feels like a running out of gas effect. I cleaned up the rotor and checked all plug plug wires and they were all good. Napa gold fuel filter and Motorcraft spark plugs have probably 1,500 miles on them.

My symptoms: truck would drive fine for a while then it would bog and feel like it was running out of gas and I needed to flip to my rear tank but both have been filled. Can't even keep it at 60 mph. After about 20-30 seconds of it doing it the truck will have a kick of power and become normal again. Fast forward to now and it will drive around the block just fine and have power but once I pull up to the highway I notice power loss. Once I get on the highway I have to quickly stop and throw it in reverse and get off the highway ASAP because it will be too hard on the truck to ascend the hill with a running out of gas effect.

What do y'all think it could be? My last assumption would be the 02 sensor. I've pulled my codes and none was pertaining to the 02, but then again it is an obd1 truck and they're slow to think. I'm going to crawl under the truck and test the o2 sensor with a multimeter tomorrow.

Any help would be appreciated 👍

 

Welcome to the site!

So I had an issue kinda like this a while ago, where the truck seemed like it was loosing power at highway speeds (55mph+), then at normal around town speeds (45mph+). At first it acted like it lost power for a split second but got worse. Then, it acted like it was completely out of power, even the RPMs would go down acting like it was coasting, when it wasn't supposed to. It got worse and worse until it started leaving me on the side of the road and I'd only get a 1/2 mile down the road. Turns out my fuel pump bit the dust, brand new unit too. I found out the previous owner had a hot wire constantly running the fuel pump and it burned it out, cheapo Chinese pump too. It acted like it had a strong prime too when it wanted to run.

I replaced the fuel pump with a Denso unit built in the U.S of A and it fixed the issue this was a few months ago. Truck is a dual tank set up like yours, but for now I only have the rear tank. Front tank is missing.

Not sure how easy it is to access your injectors, if they are accessible I'd pull some and inspect 'em, they could be gummed up if they are older, there are rebuild kits for them(?) I know they make them for the 302 (my engine) and that's what I did when I went through my truck after I bought it. I also heard that the ICM module can have a play in this, they can overheat and cause problems, I replaced mine before the fuel pump and it didn't help. I have 1990 F-150 and mine is on the distributor, I think on 92-97 F-150 through 350 it is on the fender?

Just my 2 cents, I'm sure others here will have more advice.

 

If you’ve been reading driveability threads then why did you empty your wallet throwing parts at the problem instead of running the KOEO self test to check for active and stored codes? I’m sure you also read that pushing on the fuel rail schrader valve tells you absolutely nothing. Ten pounds of pressure will shoot fuel out of the valve but that is nowhere near enough for the engine to run under load.

Run the KOEO test, check fuel pressure and you could also hook up a vacuum gauge to see if the exhaust is restricted. Put your wallet away unless you are getting tools to perform some diagnostic tests.


You have to stop and quickly throw it in reverse?

 

I did pull codes half way into this bull****. Also, the problem wasn't bad yet until I put the napa FPR on the truck, then I couldn't even accelerate to highway speeds. I thought the new part was defective which can happen, so I took it back. I put an oem one on from one of my junkyard crusades and it acted normal until a mile down the road. Some of the codes I got were 53, 85, and 32. For the TPS code I checked the voltage travel and it was out of range but the voltage climbed smoothly. I read somewhere that you can file the two holes down to make the sensor adjustable to spec, and so I did. Haven't checked for codes to see if that one came back but I will today.

 

Fuel pump and or Fuel filter. I'd change out the filter again, arrow going the correct direction.

 

A 1994 F250 with 7.5L engine and E4OD transmission should display three digit codes. How did you pull the two digit codes that you listed?

I agree the issue points to a fuel problem, but it is always a good idea to see what the computer thinks is wrong.

 

I've done the KOEO (Key On Engine Off) test mamy times before and it's always gotten 2 digit codes. I don't believe OBD1 Fords hold 3 digit codes in memory for KOEO, at least in my experience. But I did in fact check codes with KOER (Key On Engine Running) test this morning and I pulled two 3 digit codes: 116, 173

116: Engine Coolant (ECT) sensor out of range – ECT

173: Oxygen sensor not switching – system is or was rich – Single, Right or Rear HO2S – Fuel control

I only have one oxygen sensor and that is position right after the Y from the manifolds, about a foot before the catalytic converter. I did have the battery disconnected yesterday to see if it would temporarily fix my problem. I will disconnect the battery and check the codes again later with the KOER test

 

You get either two digit or three digit codes for all tests/Stored Code display. It's not both.




Ford suggests to run the Key On Engine Off (KOEO) tests and Stored Code display first. Repair any issues flagged there before running the Key On Engine Running (KOER) tests.

 

I disconnected the battery to reset the computer. When I get home this evening I will start it up and let it run for a bit and then I will retrieve the stored KOEO codes and I'll relay them here. Whenever I did the KOEO and KOER test this morning all I got was 111 system ok a couple times in a row on KOEO so then I went ahead and did KOER and got 116 and 173.

 

There are two parts to the KOEO tests and Stored Code Display. The obvious first part is the KOEO tests. If anything is flagged you will get a three digit code(s) flashed out or displayed on a code reader. If there are no KOEO issues flagged you will get the System Pass Code 111. There will be a brief pause then the single separator flash is sent out by the computer. Some code reader interpret this as Code 10, which is wrong. After the single separator flash any Stored Codes will be flashed out or displayed by the code reader. If there are no Stored Codes you see System Pass Code 111 displayed. Since you disconnected the battery you have erased any Stored Codes.

Code 116 indicates the engine coolant temperature was outside of the expected parameters. If you did not fully warm up the engine/transmission before performing the KOER tests this could be a false code. If the truck was up to temperature then you need to verify the ECT sensor output with a meter. If it is good then you may have an open connection. if it is bad, replace the ECT sensor.

Some helpful info: Ford Fuel Injection » Engine Coolant Temperature Sensor (ECT)

If the ECT sensor is bad it can trigger the rich Code 173.

 

When I got home I parked my cummins and reconnected my ford's battery. I talked to an experienced mechanic who I know very well and because I had the transmission out a couple months ago he said that there should be a ground wire that goes to one of the bellhousing bolts and I told him that I have no recollection of one being there, and I confirmed that there wasn't one there. No others to be found. I did find the missing evap vacuum hose and I hooked that back up to the evap solenoid.

Furthermore, I hopped onto the highway as quickly as possible and I made sure to keep some rpm up and it chugged for a second then it was back to normal. So I kept driving. I'm at the bowling alley as of now and when I get home I will do the KOER test and I'll see what comes up.

 

Do another KOEO and Stored Code check first. There should be a ground somewhere to the engine block, not necessarily to a bellhousing bolt. That is the main power ground. If it was missing or otherwise compromised starting the truck would be difficult.

 

Did another KOEO test and it did 111 twice then a one intermediate flash then 111 two more times. Drove home and truck was up to temperature and the 116 went away and 173 was still there. May just need to clean the o2 sensor but I don't know if it has ever been changed and if it has been then I don't know when. Family member owned it for 13 years before me. I've had it for almost 6 years now.

 

We're in a similar boat. I hope you're able to fix this.

 

I know you have changed the fuel pressure regulator but I would verify the fuel pressure at idle, idle with the vacuum hose removed, and once again under load. Also highly suggest to pull out the computer then open it up for inspection. Dozens of threads are showing the very common failure of the electrolytic capacitors. Various failure modes as well.

If those are good then replacing the O2 sensor would be a good next step.