Hey everyone, first timer here for forums. I have a 93 Hardbody, 2.4 L4 KA24E, manual. Last September I did plugs, wires, coil, cap, rotor, battery, oil filter, air filter. Then I left on deployment. Got back started right up, drove I to the driveway did a once over, everything checks out. Next day leaving for work fuel pump goes out. Replaced that, but now it idles rough, won't break 500rpm, and when I hit the throttle I get no response, so changed out TPS, and still nothing, cleaned MAF, cleaned throttle body, 40psi fuel pressure after filter, replaced fuel rail rubber hoses and like every vacuum line, took cat off. Any suggestions?

Thanks for serving the country. POSSIBLE the swirl valve located in the intake manifold is sticking from sitting for a long period of time. With the engine not running try spraying some type of foam cleaner like sea foam into the intake manifold (don’t overachieve). Let it sit for a period of time. Start engine. With the engine running slowly spray the rest of the the contents into the throttle body. If this doesn’t work check for a vacuum hose leak or a hose off located on the actuator valve which is located on the intake manifold toward the back of the engine.

So I tried this out and the low idle is still the same. The motor revs up when the spray is added even if the pedal is already at WOT. Its idling at 300 rpm and goes up to about 500 with the spray added. I still have no throttle response. I used throttle body cleaner by crc and seafoam intake cleaner. I'm at a loss on this fix. I'll take any suggestions.

Check for a bad connection at the throttle body sensor. Possible bad ground?

Where is fuel pump located? If in tank and problems began then suspect a damaged evap line off tank as a leak.

And again, thank you for your service.................

So lines on tank are good and checked my grounds, those are all working, pulled the seat out to check the ecm cir any dtc's, code 41, looked it up and referenced the AIT sensor so tested it and it checks out. I decided to go back to the fuel system and check again. This time I went to all the injectors. While running I disconnected them one by one. On Cyl 2 & 3 the truck would die, no change would occur disconnecting 1 & 4, so I took them both off and that didn't change how it was running either, I pulled the plugs from cyl 1 & 4 and on number one it was dry as the day I put it in there no discoloration, number 4 was so wet it looked like it just came out of a hurricane, I ordered 4 new ones and am gonna see how that turns out next.

Could possibly be a injector Number 4 ? Also test the fuel pump regulator. Check for a bad vacuum hose? I wouldn’t be to quick to remove the fuel rail the bolts break off with little effort. Should be able to test the injector without removing the rail?

Quick question - when you replaced the fuel pump did you replace just the pump or the complete unit? Does the truck have a low fuel light? The reason I am asking I had a squirrel chew the wiring off the fuel sending unit I have a low fuel light and replaced the unit with a sending unit without the light. The truck runs barely runs with no acceleration. Currently have the tank out dealing with this. The squirrel also chewed the fuel lines on my loader. Checking to see if the wiring is different between the sending units.

Another thought- Check the date of manufacture of the truck and make sure the part number on the pump is a correct match?

When you replaced the pump did you replace the rubber fuel lines? The lines aren’t the regular 5/16 lines you need 5/16 fuel injection lines.

Replaced just the pump, getting 44psi before the filter from new fuel pump, previous one would only put out 26psi. I did use 5/16 fuel injector line, nothing chewed up as of yet.

Do you have spark on all 4 cylinders? Almost seems like you have a couple plug wires crossed.

Not sure it would cause these issues, but maybe check the fuel pressure regulator. My rough idle and (unrelated to your issue) long crank after being shutoff for short period of time went away when I replaced my fuel pressure regulator. Checked it twice before I saw the issue. It had to run for several minutes before fuel started pouring out the vacuum side. Just a thought. Thank you for your service!