G23crawler Posted May 12, 2022 Share Posted May 12, 2022 I have a 90 2.5 2wd that iv been fixing up, truck has been sitting for awhile. Did new head gasket, plugs, wires, thermostat. It will not start on its own, but a slight amount of throttle applied and starts right up. Runs great after starting, the problem is 100% consistent. No matter the temp or how many times I prime the fuel pump. If I don't touch the gas pedal it would never start, but the second I touch it fires right up. Not to familiar with these engines. Any ideas? Link to comment Share on other sites More sharing options...
howeitsdone Posted May 12, 2022 Share Posted May 12, 2022 I think there is an idle adjuster on the 2.5. @eaglescout526knows these engines best. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 12, 2022 Share Posted May 12, 2022 Yes there is an idler adjuster. It’s the ISA on the front of the TB. I recommend adjusting the bolt that touches the throttle plate out a little bit and see if that helps with starting without pushing the accelerator pedal. That being said, once that is good and set I recommend the adjustment procedure for the ISA. Link to comment Share on other sites More sharing options...
G23crawler Posted May 12, 2022 Author Share Posted May 12, 2022 1 hour ago, eaglescout526 said: Yes there is an idler adjuster. It’s the ISA on the front of the TB. I recommend adjusting the bolt that touches the throttle plate out a little bit and see if that helps with starting without pushing the accelerator pedal. That being said, once that is good and set I recommend the adjustment procedure for the ISA. I have messed with it, did not change the starting issue. Its currently set where I want it, so if I had to adjust it high enough to start the idle would be way too high once running. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 12, 2022 Share Posted May 12, 2022 Can you verify your ISA is working? When you shut down the engine do you here some mechanical whirring under the hood or is it just silent? It sounds like to me it could not be working at all if adjusting it makes the idle speed to high. Granted on start up it should get to 2500-3000 rpm and then come down. Link to comment Share on other sites More sharing options...
G23crawler Posted May 12, 2022 Author Share Posted May 12, 2022 7 minutes ago, eaglescout526 said: Can you verify your ISA is working? When you shut down the engine do you here some mechanical whirring under the hood or is it just silent? It sounds like to me it could not be working at all if adjusting it makes the idle speed to high. Granted on start up it should get to 2500-3000 rpm and then come down. Could you explain what the ISA is? I do believe it makes a noise on shut down, kinda sounds like an external fuel pump or something. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 12, 2022 Share Posted May 12, 2022 So the Idle Speed Actuator(ISA) is what controls engine idle speed and proper start up each time. If it’s not adjusted right, it won’t start up each time right. If it’s not working the idle speed will be stuck where ever it failed. They are known to get gummed up and fail at the electrical contacts and the gears internally. Even the motor inside gets carbon build up and can not operate too funny enough. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 13, 2022 Share Posted May 13, 2022 How does it run and idle after it starts? The 2.46 is really sensitive to bad ground issues. Most notable is the ground point at the firewall. If you haven't already done so, remove the strap from the firewall, scrape to bare metal and reinstall the cable. Do the same at the head where the cable attaches. They are also prone to intake manifold leaks at the head. Make sure the bolts are snug. Also prone to rotten vacuum hoses to the intake manifold. See the pic below. Link to comment Share on other sites More sharing options...
G23crawler Posted May 13, 2022 Author Share Posted May 13, 2022 2 hours ago, cruiser54 said: How does it run and idle after it starts? The 2.46 is really sensitive to bad ground issues. Most notable is the ground point at the firewall. If you haven't already done so, remove the strap from the firewall, scrape to bare metal and reinstall the cable. Do the same at the head where the cable attaches. They are also prone to intake manifold leaks at the head. Make sure the bolts are snug. Also prone to rotten vacuum hoses to the intake manifold. See the pic below. Run and idles decently well after starting. I also wondered about vacuum, ill check those tonight. Ill also look at the grounds. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 13, 2022 Share Posted May 13, 2022 don't LOOK. Refresh them. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 13, 2022 Share Posted May 13, 2022 Yeah what he said. Those grounds have probably been in place for more than 30 years and absolutely could use a refresh. Grounds are a known culprit if 80% of electrical problems. Link to comment Share on other sites More sharing options...
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