Running rough, bad mileage, I'm stumped!

[deere842]

Hey guys,

I'm having a problem with my 1986 Ford Ranger 2.9L Manual trans, 207,000 Miles. i would really appreciate it if you guys can help me.

Heres the Deal...

When I start the truck up in the morning it idles high and when i go to drive it, it sputters and pops a little. When its completely warmed up it runs rich at times and has a very rough idle and the Rpms fluctuate between 600-1000 Rpms. I use to get 20 MPG now im lucky if I get 15... It runs great on the highway but at low rpms it runs like crap.

Heres all the things I have done:

Prior to all these problems I bought 6 new injectors and replaced the upper plenum gaskets and cleaned the hell out of everything. Ran like a brand new truck. Then less than 1000 Miles later....

New Parts:

Egr Valve, Fuel canister filter, engine coolant temp sensor, Pcv Valve, Air charge temp sensor, Map sensor, New Vacuum lines, New plugs, Wires, Distrubter cap, Rotor, Coil. O2 Sensor.

Things I have tried

Cleaning a spare AIC valve from a junkyard and installing (Not difference)

Swapping junkyard EGR control solenoid + Pressure feedback sensor

Tested the TPS and tested fine.

Tried 2 different computers.

40 psi at the rail with key on and 32 psi with engine running.

I took it by a mechanic today and he said to check and see if the timing chain could of stretched and to do a compression check, Ill do that tomorrow.
I hope I have provided enough information, if you have any questions please ask.

Thanks for all your help!

 

[kimcrwbr1]

Just for future reference allways do a compression test first. Did you seafoam the engine suck half a can in the brake booster vacuum fitting after the engine is up to temp and quickly shut it down. Wait 1/2 an hour and start it and run it around 2500-3000 rpm until the smoke clears and see if the compression numbers come up. Hopefully you saved all the parts you changed out threy are likely still good spares.

 

[RustedRanger]

Your fuel pressure looks good but did you check it while driving also? With a load on the engine it may need more fuel then it's getting. I had a problem awhile back and my pressure was pretty much the same as yours but it still needed a low pressure pump in the tank and the fuel filter was clogged bad. You can also check the FPR by checking pressure with it running and pull off the vacume line and the pressure should jump way up.

 

[deere842]

Thanks for the replys! I just did a compression test and came up with 120,120,128,128,148,135. That seems pretty decent..

I check the timing chain slack by removing the distrubter cap and rotating the crank both ways, still pretty tight!

I have done a seafoam treatment and it didnt really help much.

The fuel pressure stays about 32 psi low and high rpms.

 

[freedom5]

I didn't see where you changed the O2 sensor. It can cause a lot of problems - running rich is one of them. Also pull the vacuum line off the fuel pressure regulator when it is running and see if there is any fuel coming out or it is wet . If, so the pressure regulator needs to be replaced.

freedom5

 

[deere842]

I have replaced the O2 sensor, It says under new parts. And I checked the FPR and its not leaving fuel from the vacumm hose

 

[John Smith]

I never saw..

where you mentioned whether or not you had ever checked the codes...
I wouldn't consider working on one of these w/o reading what the puter says about things...I know it can be frustrating but it really is necessary IMHO

 

[deere842]

Sorry I forgot to mention that. I did check the codes and all that came up was 67. Which is just a safety switch.

 

[Bondo]

Thick Film Ignition module?

 

[FordRanger1991]

Sorry I forgot to mention that. I did check the codes and all that came up was 67. Which is just a safety switch.

Pretty sure your manual transmission has no neutral safety switch. Only an auto would have one. I made the mistake of buying a safety switch for my manual and just gave it to my bro who has a Auto trany. That 67 code deals with your ac and if you don't have ac then just don't worry about the code. Ford dealer says that 67 code shows up all the time on 2nd gen rangers and usually it is nothing. Also that the 67 code would not make an engine light turn on.