Hey everyone!

1988 Ford Ranger 2.9L standard/manual transmission king cab

The engine still throws the code 64 - ACT indicated 254 F/circuit grounded while in the KOEO and Continuous Memory.
I tried to get the running codes but the engine pulled up code 98 - Hard fault present. (Haynes repair manual)
This may be because the computer couldn't advance through KOEO without sending code 11. (online code reference)

I check the inlet air temperature control systems (CWM, vacuum motor, bimetal sensor, heat duct valve) for correct operation and replaced the ACT sensor.
The engine also throws code 96 - fuel pump circuit open - battery to EEC processor.
What do you think?

 

Some additional information:

the vehicle has 95k miles on it so pretty green for the year.

I recently replaced the valve cover gaskets, spark plugs, and spark plug wires.

The vehicle usually idles at 1000 rpms but idles at 600 rpms with the check engine issues.

Let me know what you think and always, thank you for responding.

 

Welcome to the forum

64 is for IAT(intake air temp) sensor, its on the upper intake manifold on a 2.9l, is that the one you changed?

96 means fuel pump fuse or relay is not working, so engine should not run at all if its a valid code


Any fuel injected engine should run at 1,000rpm when started cold
Then as it warms up idle should drop to 600rpm when warmed up, manual trans, 700 for automatic
ECT sensor reports engine temp to computer, and computer then uses IAC Valve to set correct idle RPMs


2-digit Ford code list here: https://therangerstation.com/tech_li...gitcodes.shtml


Could also be computer capacitors are leaking, look here: Ford EEC-IV
The 3 blue capacitors can leak after 20+ years, if in doubt pull out the computer and open the top
$5 fix if they were leaking

 

Awesome! Thanks for the response.

From what I understand, the ACT and IAT are different names for the same sensor.
The sensor I replaced is on upper intake manifold, passenger side, below the air bypass valve (?). I used a 1" wrench to get it off/on.
Looks like this: https://i.ebayimg.com/images/g/0O0AA...nWZ/s-l300.jpg

The codes form the link differ slightly from the Haynes repair manual.

Yes, normally the engine cold start idles at 1500 ish rpms and then lowers down to 8/900 rpms. It does run.... so the fuel pump is working and I kinda disregarded that code.
The vehicle does feel like it's running at half output/ power with the new engine issues and i may be getting reduced fuel economy, but the gas mileage is not significant. The power output IS.

I think i could replace the capacitors easy enough if they appear to be faulty and double check the ECT sensor connection.
Also, i'll go through the thermactor system (these are not used on models 1989 through 1991).

 

Check MAP sensor, should be on the firewall and connected to intake by a vacuum hose, with 3 wire connector
Make sure vacuum hose is air tight, and connector is corrosion free

Simple test for a Vacuum leak on any fuel injected engine, is to warm it up fully, and let it idle
Unplug the IAC Valves 2 wire connector, it will close
RPMs should drop to 500 or engine may stall, either is GOOD, it means no leaks
If RPMs don't drop then there is a leak

On the engine is the Fuel Pressure Regulator(FPR)
It has the Return Fuel line attached and a Vacuum hose
Check vacuum hose for gasoline, FPR can leak and fuel gets sucked in to engine causing rich running and low power
The 2 fuel lines come in from drivers side frame rail
The IN from filter runs to fuel rail
The OUT to gas tank runs to FPR, looks like a small can or filter can

You may like this site: http://www.fuelinjectedford.com/

Explains how the 1994 and earlier Ranger systems work