NOT AGAIN!! running fuel pump is back! dang im pissed!

[F 150Cobra]

frkn damn!! i had this problem i switched the ECU the problem went away now its back again? im soo pissed right now.. thinking that my truck is damegin the ECU's

it started doing this when it started raining 2 days ago.. yesterday it took 5 seconds to prime i tought it was just a one time thing.. now it will take i dunno how long i dont wanna find out.. pisses me off!!!

or maybe the ECU i used to swapp is also old and went bad?? GRR

help me guys this is really pissing me off!


bte the truck starts but runs with the chek engine light on like a big cammed truck smoking black i have to wait untill the fuel pump stops priming for it to start and run good

 

[Old_Paint]

The one second run on the pump, while it does charge the rail, is not a priming cycle. That's just an added benefit. That's a diagnostic run. The ECU gates the fuel pump on, then checks to see if it actually did turn on. After that, it turns back off. UNTIL, when you start cranking, and spark is detected, it will turn the pump back on again. The pump runs continuously while there is spark. There are no pressure switches or other magic signals involved.

Either the ECU isn't up to snuff, or the fuel pump relay is sticking on. Normally, the fuel pump relay is controlled by switching the ground. Check the wiring to the fuel pump relay and see if it's chafed somewhere, and grounding. Pull the codes. If that relay picks up when it isn't supposed to, it will throw a code. If you run the pump from the diagnostic connector, it will throw a code. Guaranteed. See if you have the code for a fuel pump relay failure. Chances are, there's a ground where there shouldn't be.

 

[F 150Cobra]

The one second run on the pump, while it does charge the rail, is not a priming cycle. That's just an added benefit. That's a diagnostic run. The ECU gates the fuel pump on, then checks to see if it actually did turn on. After that, it turns back off. UNTIL, when you start cranking, and spark is detected, it will turn the pump back on again. The pump runs continuously while there is spark. There are no pressure switches or other magic signals involved.
.

thats just the problem it doesnt turn it off back again i have to waith 15 min or more for it to turn it back off again
did it with the stock ecu.. now the other used ecu..

Either the ECU isn't up to snuff, or the fuel pump relay is sticking on. Normally, the fuel pump relay is controlled by switching the ground. Check the wiring to the fuel pump relay and see if it's chafed somewhere, and grounding. Pull the codes. If that relay picks up when it isn't supposed to, it will throw a code. If you run the pump from the diagnostic connector, it will throw a code. Guaranteed. See if you have the code for a fuel pump relay failure. Chances are, there's a ground where there shouldn't be.

thanks im gonna chek that... the relays are good.. the ecu went bad again i think.. btw i dunno if this has anything to do with it.. but
when i dont wait it to stop priming and start the engine its runs rough with engine light on and ver rich, and i press the overdrive button wich doesnt turn off btw when this is happening it fixes the problem chek engine light goes off and everthing works again.. engine runs gr8 again.. strange huh?

 

[F 150Cobra]

ok so i was pissed at the ecu.. i took the old one the original one from the truck open it and see if i can see any damage.. and what do you know i did.. i saw 3 condensor.. burnd... so i went to radio shack bought the same ones.. replace them.. they cost about 2 bucks.. and instal the new ECU... and it did it again running fuel pump. but then i rememberd.. the condensors are new maybe they have to charge... so i let it prime and it stopped after 5 minutes ( normally when its bad it takes about 15 to 30 mins) nway i started the truck everything is gr8 ... went t a party came outside.. put it in on position and only primed normal 1=2 secs.. im not going to celebrate jet.. i will see in the morning if it will take it normal time to prime... then ill celebrate wish it luck guys... ill post back in the morning.. its not 3 AM here.. so ill post back at about 9 in the morning.. thanks..

 

[F 150Cobra]

its 7:52 AM and what do you know,, i wend outside with m fingers crossed.. put it on the on position and it went EEEEMMMMM click took 1 second wooohooooo i fixed my ECU for les then 5 bucks lol ... btw i got the electrical part name mixed up its a capacitor this little things

 

[surewhynot]

Good work! Nice to see you were able to fix it.

 

[mrfixit]

hmmmm... could it be moisture is getting to your pump or ecu connections? a moisture-induced short would certainly fry a capacitor!

 

[surewhynot]

Just be careful if you hit 88 MPH.

 

[Skandocious]

"ONE--- POINT--- TWENTY ONNNNNE---- JIGAWATTS?!?!"

 

[mrfixit]

No, no, no, Tony... we didnt say he FLUX the Capacitor...

 

[Skandocious]

http://www.youtube.com/watch?v=mjCRUvX2D0E&feature=related

 

[F 150Cobra]

lol.. yep thanks guys.. im gonna fix the other ecu as well so i have a spare one.. and i dunno maybe its the mmoister frying the capasitors i have no idea.. remember they are 18 year old capacitors

 

[mrfixit]

lol.. yep thanks guys.. im gonna fix the other ecu as well so i have a spare one.. and i dunno maybe its the mmoister frying the capasitors i have no idea.. remember they are 18 year old capacitors

Yeah, I know... Tony's about twice that and he's PLENTY fried.

 

[surewhynot]

But is it due to moisture?

 

[mrfixit]

But is it due to moisture?

Moisture IS involved, yes...

 

[F 150Cobra]

dang i forgot... this ECU is Wacked!! its the original from the truck it has several problems.. Overdrive buton goes on and of when i prss the brake.. rough idle... idles go way up when in gear no power..lazy shifts... several problems, i gonna fix the one i got 2nd hand from an ambulance its good no problems good smooth idle big power improvement good crisp shifts..,, etc etc.. just for you guys to know.. all the problems an bad ECU can cause...