2000twincamturbo
Member
So my st165 was running perfect about 3 weeks ago, pulled hard and had no issues, but the floor on the drivers side was basically falling out so i decided to park her and rebuild it(wich i did). But while i was waiting for parts to come and shopping for a new mig welder so i could finish the job i decided to relocate the battery to the trunk. I used two 4 gauge wire for the starter/efi fuse then a splitter to 0 gauge all the way to the back. finally found a lincoln at a price i liked and finished up the floor. took her out for a drive and while she ran perfect once again acceleration was terrible, felt like she was pulling tons of timing. so i whipped out the multimeter and found i was only getting 10.5 volt at the pump and 13.5 at the battery with the car running wich is not right for either of them. At that point i decided to hook the pump to a relay and a switch wich gave me 12.5 at the pump and at the battery wich isnt quite right either but the car still ran just fine, decided top take her out and while power was a ''little'' better is was still awfull.
So a few months ago i decided to install my aem 340 and give the tank a refurb. got that done took her out and power was awfull then too, was only getting around 9 volts at the pump, so i did a bit of inspecting and noticed the inside of the connector was rotted and holding by barely a thread. hard wired it directly and voila! 13.8 volts at the pump and finally the car pulled like a train again and i was happy. now remember this is when the battery was still in the front of the car.
So now what im thinking is the car is not enjoying the battery relocation, it usually had around 14.5 14.7 volts at the battery and 13.8 13.9 volts at the fuel pump with the battery up front, but now with it the trunk im gettin 12.5 volts at the battery and the pump. tomorrow i think ill be taking all that out and just bringing the battery back up to the front and hooking up the fuel pump like stock again(no more relay/switch either) the car pulled/ran perfect that way but before i do i wanted to get some input from you guys. now i know some of you are gonna say check your grounds, dont worry i did and they all tested fine. i also hopped on youtube i found a clip of a dude who works at airtex explaining that even a 1-2 volt drop at the pump can cause HUGE performance issues, hard starting, poor acceleration etc...so 13.8 minus 12.5 means my pump is missing 1.3 volts. This pretty much falls right in line with what the dude on youtube was saying.
So what do you guys think?
edit: i did a bit more research and learned that low voltage at the pump also affects fuel pressure. My car is 205 swapped so fuel pressure with the car running is 36psi. A fuel pump needs at least 13.5 volts to operate the car properly. with teh battery up front i was getting 13.8v at the pump so i was definitely getting my full 36 psi. But now with 12.5v at the pump a bit of math tells me im only getting about 32.6psi. So i imagine a loss of 4 psi is ok for normal driving but not sufficient for heavy acceleration.
So a few months ago i decided to install my aem 340 and give the tank a refurb. got that done took her out and power was awfull then too, was only getting around 9 volts at the pump, so i did a bit of inspecting and noticed the inside of the connector was rotted and holding by barely a thread. hard wired it directly and voila! 13.8 volts at the pump and finally the car pulled like a train again and i was happy. now remember this is when the battery was still in the front of the car.
So now what im thinking is the car is not enjoying the battery relocation, it usually had around 14.5 14.7 volts at the battery and 13.8 13.9 volts at the fuel pump with the battery up front, but now with it the trunk im gettin 12.5 volts at the battery and the pump. tomorrow i think ill be taking all that out and just bringing the battery back up to the front and hooking up the fuel pump like stock again(no more relay/switch either) the car pulled/ran perfect that way but before i do i wanted to get some input from you guys. now i know some of you are gonna say check your grounds, dont worry i did and they all tested fine. i also hopped on youtube i found a clip of a dude who works at airtex explaining that even a 1-2 volt drop at the pump can cause HUGE performance issues, hard starting, poor acceleration etc...so 13.8 minus 12.5 means my pump is missing 1.3 volts. This pretty much falls right in line with what the dude on youtube was saying.
So what do you guys think?
edit: i did a bit more research and learned that low voltage at the pump also affects fuel pressure. My car is 205 swapped so fuel pressure with the car running is 36psi. A fuel pump needs at least 13.5 volts to operate the car properly. with teh battery up front i was getting 13.8v at the pump so i was definitely getting my full 36 psi. But now with 12.5v at the pump a bit of math tells me im only getting about 32.6psi. So i imagine a loss of 4 psi is ok for normal driving but not sufficient for heavy acceleration.