- This little truck is a 5 speed manual with 255k miles but runs strong besides the starting issue.
- the problem is when starting the truck it fires right up but as the rpm’s come down it stalls out every time! Now if you give it gas and keep the rpm’s up it will begin to idle on its own.
- little back history of the truck… i acquired it for free after it sitting for years. It was parked with this issue.
- since I’ve owned it and used it as a introduction to auto mechanics a lot has Been done and replaced.
- clutch, timing belt and tensioner, water pump, thermostat, temp sensor and sender, crank positioning sensor, throttle body cleaned, IAC replaced, egr control solenoid, fuel pressure regulator, fuel injectors pulled tested and cleaned, MAF cleaned, spark plugs and wires, pcv valve replaced, radiator replaced, few vacuum lines replaced, fuel lines replaced, battery replaced, And of course oil change and new filter. Catalytic pulled cracks welded and cleaned out. Dollar bill test over the exhaust constant air pushing out.
- All that has made noticeable difference in power and reduced the starting issue by a lot!
- Here’s a bit more information. Abs light has always been on. If i unplug the iac and fire it up it will idle on its own. I’ve swapped the iac under warranty same issue x2 new IAC. The temp gauge never really gets to half point but is also way under the minimum. The hard stop screw has been messed with not just by myself but before I owned it. I’ve had 2 mechanics and 2 family members look at it. It’s been suggested my pcm needs to be reprogrammed or replaced. One mechanic doesn’t think it’s my fuel pump.
- im left with replacing the MAF sensor, Fuel Pump, PCM, TPS replacement or reprogramming, possibly a leaky break booster. I have no codes being thrown.
- I NEED HELP ON THE DIRECTION I SHOULD GO NEXT! I do not want to replace anymore and not solve this problem. My gut says a lazy fuel pump or leaky break booster because of the abs light and years of sitting. It almost acts like it’s not getting enough fuel the way it fires right up and comes back down and stalls.
leaky break booster because of the abs light and years of sitting
I'm pretty sure vacuum leaks at the brake booster won't trip the ABS light. If there is no leak in the actual braking system and there is no air in the system, then something else is causing the light. Scan the truck for a code.
replacing the MAF sensor, Fuel Pump, PCM, TPS replacement
Don't load the parts cannon and waste money on stuff you don't need. Pressure test the fuel pump. There's a Schrader valve on the fuel rail to hook up a gauge to. It should read around 60 PSI.
Get a scan tool and read the MAF data. Ideally, it should be 2.3 g/s, but judging based on my 1999 3.0, it might be closer to 3-4. Mine hangs around 5 g/s and fuel trims are close to 0%.
Look at your TPS data. Any scan tool with Live Data can read the information. Same goes for long term and short term fuel trims. This will tell you whether or not you have any sizeable vacuum leaks.
Posted by: @onepissedsavage
Now if you give it gas and keep the rpm’s up it will begin to idle on its own
This sounds like an air problem. "Giving it gas" is giving it air (opening the throttle plate when you pull on the cable), the computer is compensating for more airflow and adding fuel. Weak fuel pumps will cause an engine to die when you do this, because they can't supply enough fuel.
If i unplug the iac and fire it up it will idle on its own.
Are you using OEM Motorcraft parts? Don't use cheap China sourced parts at the auto parts stores. Find a junkyard that has a 90 day guarantee and pull an IAC valve off a low mileage Ranger with your engine.
