I have a 1989 F150 2WD 300ci 5 speed. I love it and am slower converting it into my daily driver!!!! However..., it is starting to get annoying having to nurse it while it tries to die every other light. I have done the computer as the original had two blown capacitors, the IAC, the EGR position sensor, and the MAP sensor, plugs and wires, and it is getting cap and rotor done as soon as the truck cools down from driving home. I can not find out why it is hard as hell to start and has trouble idling. I have not found anyone that has a code reader that will work on it and the only code showing is the rear ABS light. The temp and voltage sensors do not work and are on supplemental gauges. I can not find a wiring diagram or shop manual for this thing anywhere. I have a Haynes manual but is does not help a lot. I would love to rebuild this thing but until I know what sensors are good and bad I don't want to tear it all apart and just replace everything. It may not even need rebuilding. It is very hard to start taking at least two tries to keep running. When it is idling around 500-700 it is a tiny bit stumbly and it a pronounced miss under load driving from time to time and it seems to be running rich, but most of the time if idles smooth. Any help would be greatly appreciated!

 

This is the code reader most on here use. This is from Amazon but available elsewhere. Your issue could be a bad throttle position sensor TPS. . Also you could check your fuel pressure with a loan gauge free from auto parts stores.

 

You should be able to buy a code reader for obd1 at autozone for 20 bucks or just use a jumper wire on the drivers side inner fender. There's write ups on how to do it. There's a static and dynamic test you can run. That should probably be your starting point. The 300 6 cylinders are great motors and I'll never stray away from them. Yours will be great as well as soon as you work out the kinks. There's also a possibility that your coil needs replaced. I had similar issues at idle and a new coil fixed it. Also you could check your fuel pressure. Autozone can lend you the gauge and it takes seconds to verify you have proper fuel pressure. Just my 2 cents

 

Yours should be 2 digit codes, make sure truck is at operating temp, and it being a 5 speed, remember to push in and hold the clutch while doing test.
Fuel Injection Technical Library » How To Run a Self-Test

 

I have tried this and the harness plug is getting nothing. I am getting a lot of problems from a lot of sensors on the harness side. Is there a place to get a new harness or am i going to have to rewire the entire truck? An example is the wipers are coming on at well timed intervals while being switched off. I had to out a rocker switch in line of the ground to get it to stop.

 

Checking fuel pressure tomorrow morning. Cap and rotor worked some of the hesitancy out of it. I bought it because it had the 300. Lol

 

this link-->Fuel Injection Technical Library » Home, on right side of page, shows sensors, actuators, click either, and it will show what value/range they should be in.

 

You say you replaced the MAP sensor.

I have had miserable luck with aftermarket sensors-
the symptom being 'jerking' that is far worse than
your usual misfire, usually under light or moderate load.

Made a run one day to the local 'cheap' junkyard,
picked up 3 Ford sensors, and I now have 2
(tested good) spares.
The original sensors are pretty durable. They do
fail, but not all that often.
Given the lack of quality in recent Motorcraft boxes,
I'm sticking with 'good used.'

hth

t

 

i am going to look for one the next time I am at the pick and pull. When i disconnect the TPS it hardly idles. I have another on the way because it was 10 bucks and a lot of corrosion was inside the plug. It runs fine now with a miss every once in a while and a hard start and wobbly idle. At this point i am turning my attention to the rear main seal. Anyone have a trick for installing it without the 250 dollar tool i found? Lol

 

What the hell tool are you looking at? You can change a rear main with basic hand tools.

 

my guess is he is talking about a person.

 

there is an installation tool for the 4.9. It supports the iner diameter of the seal while it goes in. Never changed one so i don't know if it is needed or if it is possible to mess up the seal if you don't use it.

 

I've never heard of such a thing. sounds like a solution in search of a problem, or a tool for somebody like an aircraft tug maintenance company, that might be doing multiple rear mains per year.

 

Tested the fuel pressure. 46. Gooing now to get the plug for the TPS sensor and wire it in.

 

Changed the TPS plug. Still a little hard to start but it is idling a bit better now. Seems like the more of the wiring harness i clean up the better it is at idle. transmission rear seal was looked at by my local shop and i was told i can do it with it in the truck and the rear main seal will be attempted this weekend sometime. Thanks for the help and if i figure anything else out for the idle i will post it here.