No acceleration.....

[timstone_v]

As you can see I drive a 91 4.0

I don't drive it on the highway too often and it drove just fine when I bought it a few months ago but the last two days I've gone out on the highway and once I get above probably 45-50 mph I have literally almost NO acceleration. The speed limit is 70 and I can not get the truck going that fast unless I'm going down a hill and I have no idea what could be causing it. I had the pedal on the floor and it wasn't going anywhere.

As a matter of fact I think once I had it on the floor trying to speed up and my needle showed me actually slowing down.

Any ideas at all as to what could be causing this?

 

[exbass94]

Automatic or manual transmission? If it's auto, is it downshifting at all?

 

[timstone_v]

It's auto...and it could be downshifting I'm not really sure. When I put the pedal to the floor it will seem like it's going to accelerate and then it just kicks kind of hard and stops.

Like to make it sound more simple. At around 50 or so I'm around 2000 RPM...when I push the pedal to the floor it will go to around 4000 RPM.....once it gets there it just suddenly drops back to around 2000 RPM

 

[swynx]

put the gear shift in 2nd gear and floor it. this may be harsh on the rpms. they will go pretty high. but this will tell you if its shifting up shift will lower the rpms. down shift will probably redline it. i've read similar posts and they've said something about oxygen sensors and the tranny shifting to to high of a gear. but that does not sound like ur case. i wouldnt set any thing i said in stone because ive never delt with this but this is just what ive read/ know good luck on your problem

 

[timstone_v]

Well the night this happened just before I was home (about 3 blocks away) my check engine light did come on but when I got home I shut it off and turned it back on and it was gone. I guess if it might be the O2 sensors I will go and have the codes checked on it to see what it might say. I'll post an update once I do that.

 

[Yellowsplash]

Check to see if your throttle plate is actually opening up all the way with the gas pedal floored...

 

[timstone_v]

Well apparently O'Reilly doesn't do engine code checks and they want like $300 to rent the machine and I don't have that kind of money right now. I won't be able to check the throttle plate til late this week cause it's dark by the time I get off work.

 

[Madracingalley]

thats crap. if they want $300 bucks to read a code machine, go to NAPA to do it yourself.

 

[Nhaz]

Well apparently O'Reilly doesn't do engine code checks and they want like $300 to rent the machine and I don't have that kind of money right now. I won't be able to check the throttle plate til late this week cause it's dark by the time I get off work.

You have listed a 1991 that should be a OBD1 system.

The machine for reading a OBD1 system is worth about 9 dollars. go buy one from walmart! and when you go there make sure its the obd1 not the obd2.

The OBDII machines are worth more but not much more.

 

[Madracingalley]

I just use the MODIS at School!!!

 

[timstone_v]

I don't know if it would work for the ranger but I remember when I had my Cougar I could use a wire to jump two pins on the connector and it would make the check engine light flash the codes to you...does it work?

 

[timstone]

Just wanted to bump this...I am the OP..guess I forgot I had this other account. Anyways...I'm still having this problem but it seems to really only be when going up hills...it still does this even with the cruise turned on...it refuses to accelerate up hills. The code I ended up reading off the computer was Code 41 (system lean)

So out of that information...can anyone narrow it down to O2 sensor or some other part that would keep me from being able to accelerate and be lean??

 

[powerranger262]

Maybe a fuel filter? Not sure but it's worth trying.

 

[timstone]

Maybe a fuel filter? Not sure but it's worth trying.

Ahhh yes....Guess it would help if I had listed all the things I've replaced recently.

I've replaced...

Plugs
Wires
PCV Valve
Fuel Filter

Cleaned the MAF and IAC
TPS voltage seems to be within good operating range.

 

[bighoss94ranger]

Timstone, you really do need to have it put on a engine diagnostic computer and have both KOEO(key on engine off) and KOER(key on engine running) tests performed. Just reading your post it does sound like fuel pressure problem. On some rangers there are 2 fuel pumps (low press. in tank and high press. on frame) Maybe check fuel pressure AND volume at rpm. hope this helps, HOSS.