I got a prob====hooked up jumper cables, i had them on backwards, now the fuel pump will not energize-- when i turn the key on i dont hear it energize, but i can cross it over at EMC test mode, the fuel pump runs but the truck will not start and run, it just cranks, i tested the relay and replaced it with a new one. still not working. any suggestions what else might be wrong. really need some suggestions.

 

i would check every fuse on the truck there should be a main fuse like a 160 amp or something that will blow when jumped backwards

 

i check the fuse are ok 160 fuse cant find it think MR _bentwrench

 

Have you checked the main power distrubution in the engine compartment. Its a plastic box on the fender normally on the side with the battery. The plastic on top is a cover that comes off. Inside there are several large fuses and some relays. If you haven't checked there then that would be your best bet.

 

i checked the ECM relay, it might be bad, i am having it cheked today, has anyone heard of an ECM relay??? it looks like the fuel pump relay but i am told that it is different. I get spark, not sure about fuel, i get the fuel pump to run by crossing it over, but it dosent prime when i first turn the key on. going to test the pressure on the fuel pump today, what is the pressure supposed to be on this truck? in Haynes it says 30---40 lbs. sounds like pretty high pressure. thank you Pestco 1 by the way can anyone tell me where to locate the computer in this 89" f150 lariat truck, cant seem to find it not behind glove box, i already removed 2 boxes, looked like puter, but advance said it was for the radio???? had 5 wires plugging into it.. other box had 2 plug in it 9 wires to each plug, was told that it went to anti lock brakes. anyone got a picture of 89 ford computer location or what the computer looks like. it would really help thanks for your time and helpl thanks mr bentwrench for your help too.

 

check my thread in this post "302 won't stay running", maybe something there will help.

 

i went to ford dealership today--said EEC power supply, mine had 4 plugs replacement part they had had 5 plugs, they told me that it should work anyway, just break the 5th plug off. dealership did say that this EEC did power the main computer, i wonder if this is what mr bentwrench is refering to as the 60 amp breaker? i used test light with the key on, at the fuel pump i cannot get any power. but if i go to ECM test mode and cross it over i have power. the fuel pump tested at 50 pounds of pressure- is this too much. i also found out this truck is manufactured in Mexico. it is in the vin # 1 USA--2 Canada--3 Mexico-- is this correct does anyone have any info on this. urgent any reply is greatly appreciated. i really miss driving my truck

 

have you checked the inertia switch yet?

the inertia switch is located on the driver's side of the firewall to the left of the brake pedal.

the red button should be pressed down and stay there.

the specs i get are 45-60 psi 4.9L
30 - 45 all other engins but i think it would start if you had pressure with the key.

you said you have the haynes manuel take a look at page 4-19 general eec-iv poer relay and ground checks.
its lookin more like bad eec relay or even a smoked eec-iv

step 8 on page 4-9 says if fuel pump fails to power up at start up but does run when using the self test suspect faulty ciruitry from the fuel pump relay to the eec-iv module or a bad eec-iv module.

 

yes i checked the inertia switch, with the key on there was no power getting to it. but did presure check, it had 50 lbs pressure. i bought new fuel pump relay-new EEC relay--still no power. fuel injectors are not powering up, i sprayed either into it ---it started up and run, where do the fuel injectors get their power from, how do i trace the source of power for them. thank you mr bentwrench for all your help. i am still lost on how to locate the problems with this truck.

 

the EEC power supply--ford dealership sold me a 5 prong instead of a 4 prong that mine had, does anyone know if this will make a difference, do i need to keep hunting till i find a 4 prong replacement, what will not work if i dont have the 5th prong? any reply will be appreciated. has anyone else encontered this problem before. any help is appreciated. i really miss driving my truck:

 

looking at the wiring diagram it looks as if the red injector wires have a diode in line with them this protects from current flowing the wrong way. hooking up cables backwards could have smoked the diode.

not sure where it is on yours but on they newer ones it is in the centrul junction box under the hood with all the fuses.

ussually a little black thing about the size of the med. fuses
with a picture of a line with an arrow on it pointing at another line.

 

Injector pluse is triggered by Ign. module. I am not as sure about fuel pump power.

 

yesterday i installed the 5 prong EEC relay that i purchased at ford dealership. when i hit the key it started the fuel pump but i couldnt shut it off with the key, had to pull the battery terminal to get it to stop. i bought ignition module and today i will install it to see what happens. today i am going to check the diode to see if i can find it. thanks to all your help. it is greatly appreciated. i miss driving my truck

 

why where you jump starting it in the first place was the battery just dead?

 

mr bentwrench---after 3 days without starting the battery goes dead. i went to autozone and purchased new alternator and battery with lifetime warranty that was 4 years ago. i have replaced the alternator every year. At autozone thay have checked the truck and they tell me that there is nothing wrong with the truck, but the alternator goes out about once a year and they replace it. i have had it checked at the ford garage and same story, but it still goes dead after sitting for 3 days, not enough juice in the battery to light the inside lights. that is the reason i was jumping the truck on monday morning. it had sat from friday till monday. i put the cables on for just a second and realized that they were backwards. it was very early.5:oo am, i turned the headlights on to let the battery drain down and went on to work it sat alll day , that evening i charged the battery and tried again and it would not start. still not able to find the problem. i really appreciate your help mr bentwrench---i am really puzzled as to what is wrong.