I have an '90, F150, 5.0L, auto, with 172k mile. I have been having issues with it running rough and coughing, backfiring on acceleration. New plugs, wires, cap & rotor but no change.

Yesterday while sitting at a light on a slight hill, I gave it gas to go and it just quit. I tried to restart but it did not even attempt it. The fule pump was kicking on and I know it was getting fuel.

Luckily there was a parking lot right behind me and the hill helped. I went back this morning and it started right up.

I am in lower Mich and it is really cold. I thought about water in the fuel line that froze and blocked it off. But when I tried to start it after it died I pumped it a few times indesperation and I could smell gas, so no blockage.

Could it be the pump? It had been driven about 3/4 of a mile and not warmed up before it quite yesterday. I have not tried yet to get it home. That is my after work project.

Could it be a sensor? I have never had a CEL come on, bulb?? Tried in the past to get codes but they could not get it to read anything.

Any ideas??

 

Dual or single tanks

 

Gtg so if its dual tanks it could be your tank relay switch happened on dads '96

 

does the fuel pump run for 2-3 seconds with key on engine off or does it keep running with key on engine off?

will it start with starting spray (ether)?

 

Ok her is an update. It has duel tanks with a defunked front tank pump. Went back this morning and it started right up. Hmm....

Went there just now to get it home and it started and ran fine for about 1/4 mile and then died and would not restart. I was able to get it started by switching to the front tank until it started running and then switching back to the rear. It did not run that great, kinda ruff. Would die every time I put it in gear. Would not restart unless I switched tanks.

I think that the pump just primes and then goes off. I did not pay too much attention.

So $65 to tow this thing 4 blocks, it is back in my frozen drive way. It acts like a carb that has the choke stuck closed. Can that happen on a FI?

 

do what i said and post results.

i bet the computer may be the problem.

did you try to read codes with a reader?

 

Tried to read it over the summer but Autozone could not get any readings. It was like it was not even connected.

Pump runs for a few seconds (primes) and then shuts off.

Have not tried starter fluid, too dark and cold right now. LOL

 

I don't know what you mean by a defunct front pump since it will only start when switched to the front tank. Will it run okay on the front tank? Have you checked fuel pressure on either tank? I didn't change my fuel filter until I had over 200k, have you ever changed yours?
I don't envy you with the weather up your way right now.

 

the clue is the not being able to read the codes.

you need to find out why.

 

The plug for the codes was and is caked in a thick grease, oil, dirt combo. I was not too worried about it since I never got a CEL. It has warmed up a few degrees so I will try some degreaser on it.

I have not checked the fuel pressure. Mostly 'cause I just got it home. I know the front tank pump is bad. It has been for a few years now. Don't need it so I haven't changed it. In the past it would not even try to start on the front tank. It would die after a few seconds if I switched to it when it was running.

When it starts on the front tank now it will only run for 3-4 seconds before starting do die. Switch to rear tank and it runs. Just rough and dies under load. Will not restart from rear tank.

I have not changed the fuel filter and have around 175k on it.

Also when I start it on the front tank it fires immediately. There is no long cranking to get it fired.

 

so are you waiting until you hit 200k to change the fuel filter?

 

Filter has now been changed. Tried to get codes but no luck. Must be a short or cut wire or ???? Not reading anything just like it is not hooked up.

Filter did not help problem. Could it be the air bypass?? Is there a way to go around this sensor/valve to test it? New one is $75, very low budget after Christmas and can not keep replacing items.

I will be checking fuel pressure in the next day or so, need to get a gauge. Any thoughts on the pressure regulator being bad?

 

Ok I checked the air by-pass by letting it idle to op temp and then unplugging the sensor. It died immediately. Yes it will start and idle but that is it.

I was able to manually pull codes. Need major help:

KOEO

1 2 1 2 4 5 2 2 1 2 4 5 2

Long pause then 1 1 1 1 1

KOER 4 and then nothing, I waited a minute or so.

I did this twice and got the same numbers. It is hard to tell exactly how long the pause is between the KOEO numbers so I don't know where the break should be.

HELP!!!!

 

See if the diagram on this page helps you decipher the flashes: EEC IV Self Test hookup

 

Provided your EEC sends the 3 digit codes like my brothers '90, this is what I come up with.

212 - Loss of IDM input to EEC or SPOUT circuit grounded. (Short to ground in spark output circuit)

452 - Computer detected an error in the VSS or PSOM signal during the last 80 warm-up cycles. (VSS - Vehicle Speed Sensor)