Truck
1989 F.150 4x4 5 speed 300i6 154,000 miles

When I go to start the truck it cranks fine but will not start unless you give it a little ether. Then it will run but idle like crap. Other times when you fire start the truck it will start right up and run fine. I tried to flash the codes and I believe I got (new to the early OBD) KOEO 33, 67 KOER 21, 33, 77

When it wouldn't start I checked for spark and got a good spark and when I checked the fuel pressure it goes to 50psi when you turn the key and stays there during cranking. Also as a side note the PO put on a new fuel tank sending unit, fuel psi regulator.

 

only code that sounds troublesome is code 33. 50 psi is way to high of fuel pressure what idle pressure. how is your gauge hooked up what about wide open throttle. any recent repairs done tune up. 50 psi should be ok how ever these engines are particular some want the higher pressure some do no so 50 seems high but may not be but do not rule it out

 

The gauge is just hooked to the test port on the fuel rail with a foot of rubber hose. I`ll verify it with another gauge tomorrow and check wide open, but it runs fine with throttle. It just occasionally will not start and then runs rough. Any other time it runs fine. Also the PO put plugs/wires on it.

 

make sure all the wire are even and not crossing no misses through out the rpm band. egr sounds like its an issue hear and or the high fuel pressure. was it a cold engine when you did the test.

 

hey I had this same issue... see if this works..... the is a sensor on the thermostat housing the unplug it .. it is on the front of the cylinder head behing the radiator on top.... mine did this and never would idle right . unplugged it never had that issue again

 

It was a cold engine. Ill run it to work and back tomorrow, then retest to get some good hot results.

 

Last week I ended up putting a cap/rotor on the truck because they looked bad and the truck then ran fine for a week. I drove it to Georgia and back (1400 miles) with no issues. So low and behold today after the truck sat for 6hrs I went to start it, same exact issue as before, it wouldn't start.

I pulled the cap/rotor and wiped them off. Then the truck fired up correctly again. I drove it a bit today, let it sit and now it wont start again without either. The fuel psi idles at 35 and will go up to about 45 when floored. Ive checked for spark. It seems fine (unless it is out of time) Also with the spark plug out, you can smell the fuel, so Im assuming its getting fuel properly. I also checked for any loose rubbed wires and wiggled the harness while running to see if it would quit surging but had no change in idle.

 

Your fuel pressures are too low, it should be around 45psi at idle and 55-60psi at WOT.
You have either a plugged fuel filter, bad fuel pump or bad fuel pressure regulator.

 

is this the original engine in your truck. the later model six cylinders had lower fuel pressure than the earlier models.

 

He said it was a 1989 and a 1989 4.9L should have around 45psi at idle and around 55-60psi at WOT.

 

yes the truck is a 1989 does not mean the engine is from a 1989. he never said if it was original.

 

The fuel pressures I posted are good from 1989 (or maybe a few years before) through 1996 the last year for the 4.9L engine.

 

It is the original engine from the 1989 truck to my knoweladge. It runs the same fuel psi when it is running correctly and when surging, so Im not too worried about that. I`ll check into the fuel filter though.

 

well you did have trouble codes. is your MIL on now. does it idle high at all or still the same.

 

Everything acts the same screwed up way. The MIL is still on. Im gonna run it tomorrow and check for new codes in case anything new showed up.

It doesn't high idle at all, just surges. I am kind of tempted to just throw a new distributor at it with a ignition control module since it seems like it likes to start running right after I mess with the distributor.