Hey everyone Im new here, I have an 86 5.0 AOD 4WD. Ive had this truck for a little over 3 years and no problems until a few weeks ago. itd been sitting for a couple weeks and went to start it and it wouldnt start. wasnt getting fuel. I changed the fuel filter, and still nothing. I dropped the tank assuming that it was the pump, but found that wired direct my pump does work. I put it back together. Then I stumbled on a post here with the eec test plug ground out. I grounded the fuel pin, and when I turned the key the pumps came on, and I heard the relay click. I checked the grounds at my pumps they seem good, and I dont know if I should be but I left that pin grounded and had to drive it to work like that for lack of transportation. I checked my fuel pressure running and I have about 30psi, then remove the pressure regulator vacuum and it goes up to about 37 pounds. does that seem about right? I also tried switching the relay, the autopart store didnt have one so I just got a couple from the junkyard and all 3 do the same. Im not sure how to check the relays, none do anything until I ground that pin on the eec connector and they do make a sound when the pumps come on. both the in tank and high pressure pumps come on. Thank you for reading my post, I hope someone has an idea because I cant figure it out.

 

Lets back up a little, with 30 psi at rail, fuel pumps are doing their thing. Either the injectors are not firing or you have no ignition. Either is simple to test, simplest is to spray starting fluid into the intake, if engine starts and then stalls, ignition is OK and fault is in the injector control. If still doesn't pop, then check for possible jumped timing chain.

 

Thank you for the response. The truck runs. The only way I could get it to run and get the pumps to turn on is to ground the eec plug. I have been driving it like this it seems to run ok but I want to fix it right. I hope you have an idea, thanks again.

 

I would get a code reader and see if there are any codes.

If you can make the pump relay work by grounding the test plug pin then the relays are OK. The EEC is what turns on the pump and grounding the test pin just bypasses the EEC and forces the pumps to run. See the test connector and EEC pin 22 in the EEC 3 drawing below.
The pump relay is shown in the both the single or dual tank diagram below whichever you have.

The EEC may be bad or wiring somewhere in between or there could be some reason the EEC is not telling the pumps to run such an another input. Something tells the EEC that the engine is running... Guessing that it is the tach line or one of the TFI ignition module lines to the EEC. All things to check.


The entire circuit is shown in the diagrams below including the wire colors.

Be sure to check the grounds before replacing any components. There is a ground connection on the block near the firewall and driver side valve cover.

Note that you should be careful when running the pumps continually. Don't let the pump run on an empty tank. Don't leave the ignition on for long periods of time if the engine is not running. Normally the EEC turns off the pumps after 3-5 seconds if the engine does not start.



Single Tank:
http://i608.photobucket.com/albums/t...singletank.jpg

Dual Tank:
http://i608.photobucket.com/albums/t...0/duelfuel.jpg

EEC 1
http://i608.photobucket.com/albums/t.../8650EECp1.jpg
EEC 2
http://i608.photobucket.com/albums/t.../8650EECp2.jpg
EEC 3
http://i608.photobucket.com/albums/t.../8650EECp3.jpg

 

Thanks for the reply. I just ran my codes and I have a code 18 its for IDM circuit failure or spout connection grounded, code 31 PFE or EVP circuit below minimum voltage, and code 87 voltage not detected on fuel pump monitor. Any ideas where I should go from here? Also I put in a toggle switch to the test ground so I can have the ignition on and the fuel off. Thanks again.

 

Does anyone have any ideas on where I go from here? Thanks.

 

Going back to your entry on the 14th, you are jumping the circuit to make the pump run continuously. This brings up a dump question, has anything been done with the oil pressure gauge and circuitry? I aks this because the oil pressure sending unit is what tells the PCM to run the fuel pump after the engine starts. If this has been replaced with a direct pressure gauge, the PCM is not informed that the engine is running.

 

thank you. I Have noticed the oil pressure gauge hasnt been reading correctly. Maybe the oil sending unit or the connection to it? The gauge is still the original one. I will have to check when I get off work today. Thanks again.

 

I was wondering, if it is not grounded and just with the key on engine off the pumps should come on for a few seconds but dont come on at all. Then could it still be related to the pressure gauge? Thanks again.

 

I don't think so, the initial pump on for 2-3 seconds is for establishing pressure in the rail (priming), the oil sender has nothing to do there. After engine start, then a second circuit feeds the pump. This is the one I was hoping is your issue. As the PCM is costly, you might check with a junk yard, make sure the engineering number is exactly the same, only let Ford tell you if the number is a replacemnet.