Hi I’m a long time lurker and first time poster so let me know if I make any mistakes.

Not sure where to fit this in, but for background the previous owner said he replaced the TPS sensor, O2 sensor, cap and rotor and a few other things. Also the ad said the transmission only has 50k on it but I’m not sure when that was done.

So I recently bought a 1994 F150 4x4 with a 302 and an automatic transmission. It made the 2 hour trip home just fine, and I took it to the store a couple times no problem. But today I took it on it’s first trip down a highway, I stopped for gas, put $20 in and as I left started having the following problems.

It shifted into first, second, and third just fine, but as I got into overdrive at around 55-60 it would get up to speed and then steadily slow down, I tried to give it more gas but it wouldn’t speed up. The only way to get it to was to put the petal to the floor and after a bit it would downshift hard and then realize where the petal was and speed up. This went on the whole way. I also noticed it had a hard time getting into gear sometimes. On the way back home the throttle response got worse, had a hard time getting through a light because it took forever to react to pressing the petal. Once home i started it again and it died on me once, it’ll run now but it smells like it’s running very rich and the idle surges sometimes and sounds rough.

I’m not much of a mechanic but I’m happy to give any more information, also I’m sorry for the long winded post.

Also this post outlines almost exactly the problems I’m having with possibly some better wording but no answers sadly.
https://www.fordf150.net/forums/viewtopic.php?t=103146

 

Welcome to the site..

It almost sounds as if it’s starving for fuel. Possibly a fuel pressure regulator leaking into the vacuum line if it’s over rich. You might pull the vacuum line off the fuel pressure regulator hose and check to see if any raw fuel is there. Also, I’d check for spec fuel pressure/volume at the schrader valve on the fuel rail to rule out fuel deprivation. Other possibilities MAP/MAF causing over fueling.
Is the check engine light on?

 

Thank you for the help, I’ll check the vacuum line today and I’m not sure how to check the fuel pressure at the schrader valve, will I need something to test it with? Sorry I’m pretty new to this. Also I checked the MAF yesterday and it seemed to be working fine and wasn’t dirty. I’ve also gotten it to run and idle a bit more normal after cleaning the cap and rotor. Will be taking it for a drive today after checking the above. Also, could all of this have been caused by some bad gas? This was the first time I filled the tank and it got pretty low prior to that. Thank you again!

 

The Schrader valve is on the fuel rail, you’ll see it topside on the intake manifold. It looks like a tire valve on the rail. You would need a tester to check for pressure there to prove out a healthy pump/filter as well as some testers will let you run fuel through to verify flow or volume to make sure there’s no restriction for fuel filter ect.
Some parts houses may have loaner test equipment, or even Harbor Freight and such sell low cost testers.

The reason to test for both PSI and volume is, you can have a fair pressure, but may suffer from less than spec flow, although in most cases one will fault the other. Like a restricted fuel filter may indicate a decent PSI low end in RPM, but on hard throttle applications the fuel restriction adding to a flat throttle response may occur. If the concern can be duplicated ? (stall or hesitation driving or stationary ) a simple pressure test gauge installed on the rail and in view of the driver,, then on a test drive under a stall etc the operator would see the pressure fall off during the event..

Polluted fuel can cause all sorts of grief, and a simple test like mentioned usually would point it out. Also,, in tank fuel pumps need or should maintain a minimum amount of fuel for pump cooling otherwise the potential is there to shorten service life...Sometimes pumps that are audibly louder can be an indicator they may be going south, and to verify spec fuel supply isn’t a bad idea if high mileage, flat throttle, no start and so on.

You didn’t answer if the the check engine light had come on?
Generally if electronic engine management issues, ignition misfire, injectors etc and/or trans issues, codes will normally be stored/available. With fuel starvation, depending,, codes or a CEL may or may not set..

 

Thank you for all the info! I’ll look into a testing kit this week and see what I can do since it does seem like a fuel issue, especially since it happened right after I put fresh gas in after running on possibly old gas. Maybe it worked it’s way through? And sorry for not answering about the check engine light, it does come on intermittently and usually when the idle starts to become irregular. I drove it today and it actually drove fine except for the intermittent check engine light and a rough idle at times. Also would a fuel treatment do any good?

Thanks again!

 

If the CEL has been on, have the stored codes read.
Most auto parts stores will have a scanner to check for codes, normally at no cost.. It’s important to know ‘why’ the lamp was on, since the possibilities are many and even if intermittent ON. Most times it will lead to a starting point for a diagnosis.. Fuel treatment is fine, but if filter restricted ect, high concentrations of debris including water, it won’t help. If you bought fuel from a reputable service, chances are it was fine. But, doing some checks as noted prior, helps to narrow the possible cause/s

 

Just after refueling, I would be looking at the fuel filter.

 

I asked at my local O’reileys but since it’s OBD-1 they couldn’t do anything for me. I’ve seen people use a jumper or even a paper clip to jump the pins to get the light to flash and read the codes, is this a safe option? It doesn’t seem like it but I’ve seen people do worse. I was thinking of investing in a scan tool but I’m not sure where to look. And ill look into checking the fuel filter this weekend. Also is it a single filter somewhere under the driver side of the cab?

 

Thank you, I’ll be checking that this weekend and ill
post my findings.