Hey Garett Here, Been reading the fourm for a while but first post.

I hope I haven't missed the answer to this already in my search. I have seen similar problems but nothing that seemed to be the same

I have a 92 f150 with 302

I only purchased it two days ago. When buying it the owner said hed been having a problem, It would sputter and not get fuel so he replaced the filter (which was the original filter) within the last few weeks and it solved the problem and its been sitting to be sold since. He was also only using the front tank

However im drivng it and had the same problem so decided to try the rear tank and it worked fine and then did the same thing. So it starts up fine drives 20 minutes sometimes longer then will sputter and not get fuel but if i just switch tanks on the fly itll keep going until it starts sputtring on that tank so I swtich back. So on and so on.

I did run it out of gas taking it home as there wasn't a station on the way and I misjudged the fuel I had. Im wondering if in doing that I picked up more dirt and clogged the filter again as they are the original tanks.

So I'm going to replace the filter. Just wondering if there are any other suggestions or known problems causing this.

Hope the information makes sense and any advice is much appriciated.

Thanks.

 

If he never used the rear tank, there's a good chance that there was some gunk floating around in there that clogged the filter. But it sounds like you're getting gas in one tank and its transferring back to the other. that would be from a check valve thing that operates between the two tanks. it transfers gas back and forth when it goes bad. somebody here will know the exact name of the part.

 

Thanks for the reply. If that's the case what about it causes the sputtering, loss of pressure in the system? And if say I only used the front tank and were to keep putting fuel in it would I end up with a full tank in the rear? Would that be a way of ruling this out or determining its the problem. Thanks again

 

The loss of pressure could be from the filter getting clogged. If the tank pump can't make pressure beyond the filter you won't get a good reading for pressure. But yes, if you drain the back tank, and keep filling the front, eventually the rear will be full again.

 

How do you know it is not getting fuel after 20 minutes?
Have you put a fuel pressure gauge on it?
If both tanks quit after 20 minutes each and you do not have fuel pressure then it sounds like you have two bad fuel pumps (FDM).

 

Hey, Thanks for the replys again. I've been away from a computer so sorry for the delayed response.

The truck is now not having any problems on the rear tank since i started the thread, On the front tank ( I measured every 15 to 20 kms ) it starts sputtering but will idle fine for another minute but when you try to give it gas it stalls then it will start up and idle again and stall and after a few tries just wont start and wont start again until its run on the other tank. Thats why I thought it may not be getting any fuel. Sound like a bad fuel pump on the front tank?

Now im more concerned that it idles high around 1250 in park and nuetral and normal around 750 in drive and goes into gear really hard, shifts hard into second then the rest are fine. I read this idle problem could be a vaccum leak but I went all over the engine compartment with a propane cylinder and didnt notice any changes.

I ran the codes and get

KOEO
122 TP sensor cicuit below minimum voltage

CM
122
542 Fuel pump secondary circuit failure PCM to ground

KOER

When I tried this i couldn't get it to give me the engine I.D code it jsut started blinking codes which were

968 Hard Fault present
122

I dont know much about the codes but the 122 and 542 sound like they are related to my problems and will research them further. However the 968 I havn't seen much info on other then It will give that until you clear the KOEO and CM codes is this true?

Thanks again for any help

 

Most of the time the 122 turns out to be bad wiring or bad TP sensor.
Most of the time the 542 turns out to be that one of the fuel pumps is bad.

You do not run the KOER test until you get a 111 from the KOEO electrical test.

 

Excellent. I have a parts truck and a multimeter so ill check them out soon. Thanks again for your help.

 

No voltage at the TPS when I checked it according to the haynes manual. I also noticed the insulating is worn off the wires up close to the tps. I thought what I've read said that the lower the voltage at the tps it would idle lower voltage to high idle to high but this doesnt seem to be the case. Also just to double check the pigtail off of the tps isnt plugged into anything but i also cant find anywhere's to plug it into and appears to be unplugged in the haynes manual. Is it just there for testing.

Im coming in just under 10mpg and I only do hwy driving to work with the truck so I have some other basic things to still go through as i just picked up the truck. But I should be getting a little bit more then that right?

 

Yes the plug needs to be plugged in to another plug.
No it is not there just for testing. It tells the computer how open the throttle is.

 

Thanks I gave up to qiuck in my search for something to plug it into and found it tucked away. Plugged in I no longer get the code 122 below minimum voltage and get 123 below maximum voltage. I get the 5 volts ref but only .4 on the closed throttle and doesnt sweep at all with the throttle travel . Truck runs the same weather it's plugged in or un plugged. Safe to assume I need a new TPS?

 

Yes it does sound like you need a new TPS.