Doesnt run when i give it the tan/wht to #86 terminal on relay but when i put it direct to the fuel pump grey 12v feed it runs? Not sure why the hell this isnt working? ive tried 3 different relay's?? something is off...........
DIY Fuel Pump HotWire/ Concern
- Thread starter 87chrisss
- Start date
Doesnt run when i give it the tan/wht to #86 terminal on relay but when i put it direct to the fuel pump grey 12v feed it runs? Not sure why the hell this isnt working? ive tried 3 different relay's?? something is off...........
- Joined
- Feb 18, 2006
The original pump feed (grey wire) should be providing the signal to the hot wire relay now. Verify the factory fuel pump relay is working (under the hood) and the grey wire is getting power. The ECM signal and factory relay has to be working.
From there it's cut and dry.
The grey wire energies the coil in the relay pulling in the contact and making the link between the two connections #30 & #87.
From there it's cut and dry.
The grey wire energies the coil in the relay pulling in the contact and making the link between the two connections #30 & #87.
i have it setup just like that, think i just found the problem... when i turn the key to let FP prime, it doesnt, reason being the voltage on the stock wiring harness isnt 12 volts, stops @ 11 volts for a 1/2 second and trickles down fast to 0..Which im thinking isnt enought to kick the switch in the relay.. Im thinking of running a diode to # 87 to allow some voltage to get to the main feed, and prime the pump and once car turns on the relay will open and in turn give me the voltage i want on pump feed,
UPDATE**
Well i soldered a diode from 86-87 terminal on relay, it worked..BUT the voltage was still a little low on plug to fuel pump and the relay would randomly click every so often. I got fed up and called my buddy he's an electrical wizz, even runs an underground radio station.. He's cool.. Anyway's he told me to swing by his house that he would give me the solution.. I got to his house and he tossed me a FORD OEM relay he told me to try that should fix my problem... SURE enuff fixed my problem.. He told me the Ford and some BOSCH oem relay's will open switch @ 6 volts some @ 8 volts.. w,e it was im happy...turned the car on and checked the pump feed & it was an outstanding 13.8 volts! Not only did i notice the pump screaming in the tank but the scanmaster also showed me 13.6 13.0 Volts and fluctuating which i never saw prior to all the big grounds i made in the back. Great now im not so worried.. Thanks, guy's!! And Thank you Rick, hey ever get to install that 6765?
Funny, i bought 3 NEW relay's and none wanted to work with the voltage that my car was supplying to the relay.. I get a used FORD relay and poomph it worked.. Even though FORD saved my day seems like they are always near our back bumper..
Well i soldered a diode from 86-87 terminal on relay, it worked..BUT the voltage was still a little low on plug to fuel pump and the relay would randomly click every so often. I got fed up and called my buddy he's an electrical wizz, even runs an underground radio station.. He's cool.. Anyway's he told me to swing by his house that he would give me the solution.. I got to his house and he tossed me a FORD OEM relay he told me to try that should fix my problem... SURE enuff fixed my problem.. He told me the Ford and some BOSCH oem relay's will open switch @ 6 volts some @ 8 volts.. w,e it was im happy...turned the car on and checked the pump feed & it was an outstanding 13.8 volts! Not only did i notice the pump screaming in the tank but the scanmaster also showed me 13.6 13.0 Volts and fluctuating which i never saw prior to all the big grounds i made in the back. Great now im not so worried.. Thanks, guy's!! And Thank you Rick, hey ever get to install that 6765?
Funny, i bought 3 NEW relay's and none wanted to work with the voltage that my car was supplying to the relay.. I get a used FORD relay and poomph it worked.. Even though FORD saved my day seems like they are always near our back bumper..
- Joined
- Feb 18, 2006
Are they 4 pin or 5 pin relays?
Make up a couple pig tales and test them on a battery. If they don't click, try reverse the polarity to the coil.
Make up a couple pig tales and test them on a battery. If they don't click, try reverse the polarity to the coil.
I just checked the voltage on two of my cars. Both have hotwires. One car shows 9.9 volts, the other 7.9 volts. I checked them with a battery charger connected to the battery, with key in the "on" position, and the pigtail disconnected at the fuel pump. One thing I noticed is that there is more voltage coming out of the alternator when I checked voltage at the alternator it with the car running (14.xx) compared to the battery (13.4). So are you supposed to back probe the pigtail with the car running to get an accurate check? My probes are too big to push into the pigtails. Thanks.
Yea i checked with the car running. With the car off my hotwire #30 on the relay would always show 13+ volts. The problem was with the stock harness FP feed. I noticed when i would turn the ignition on, the ECM would only send 11 volts and trickle down very fast to 0 in less than a second. That is considered the FP prime.. Once the car turns on it will receive the direct voltage. So in my case the #86 terminal on relay wasn't seeing enough voltage to click the relay and allow the #87 terminal to receive voltage which is my output 12v to the FP. With the car on my output #87 on relay is seeing 13.8 volts sometime's 14volts.
Not sure im understanding your question, i turn on the car and get under the car and check the fp feed wire and ground the other wire with my multimeter. I also check the Relay terminal's to see if i can notice any voltage drop or difference in voltage. I would have my girlfriend turn the ign on while i was checking stock harness FP feed, because when i had it wired to #86 terminal on Relay it wouldnt click the relay to allow #87 to see the voltage to prime the pump.
