My car wouldnt start once again...Just replaced FP for the third time, relay is good, i can hear it click. There are five wires into that relay...Orange (power), Green with white, Black with white, Solid Red, and Gray. All of these but one were getting 12V for about two seconds when the key was turned onto run, and then back to .02V once it was done with its "cycle". The black wire wasnt getting any voltage at all, ever? What does this mean? Is it a bad ground that has been causing my fuel pump to go bad so fast? My FP is not priming either...what are all of the other wires and can I splice into that black wire and make my own ground? If i can make my own ground, where would you suggest? Thank you all for your much appreciated help.

~Sean

 

anyone? I need to work on this in about an hour.

 

wiring diagram from a quick



https://www.thirdgen.org/techbb2/sho...ight=fuel+pump

I would verify juice is going back to the pump first. If not, look at the diagram, and verify each wire for the relay circuit is OK. There is a way to jump the fuel pump from the aldl. Looking at the diagram, it looks like you put 12V to terminal G of the aldl with key off.

 

that blk/wht wire is the ground - shouldn't have power. and runs through a splice, and eventually attaches to the back of the driver side head.

 

If I have a bad ground from the FP relay, can I cut the wire by the relay and splice in a new wire and ground it out on my frame or something? Would this be a good way to test to see if it is the ground? Also, when I was out trying to start my car, I wasnt hearing the relay click at all? What ideas do you have for me on things to check? It is getting spark. Thank you.

 

also, what the heLL is the ALDL...and how do i check all this stuff? Something keeps causing my FP to go bad because i have gone through 3 in the past month

 

ALDL is the diagnostic connector under the dash, right hand side of steering column. I would check the wiring in the connector for the fuel pump relay first, as it was working in the first post but is not now. Look for corroded, loose wires or anything that would cause a bad connection. Print out the diagram in the link, and verify each wire is working as intended (i.e. the ground wire has continuity to ground, the power wire has 12V, etc). You should find something that is causing your problem.

 

I can not read schematics very well...can someone tell me where the hell these wires are and where they go from and how I should check them and all the details...I am not to mechanically inclined, but I can follow instructions well. I want to check all of the wires in my Fuel Pump circuit and check anything that can cause my FP to go bad. I have replaced the relay, fuse, and oil pressure sender switch, along with the fuel pump 3 times and i am having the same problems. Thanks.

 

BTW...everytime I replace the Fuel pump it starts right up and doesnt have any problems until a day or two later...sometimes even a week later.

 

Does the distributor send out a signal to the ECM that could be screwing with the FP...I heard something about it, but I wasnt sure. Any info on that would be great

 

also, is getting rigging the fp relay ground wire to the frame bad? will it mess with the computer at all?

 

back probe ground wire blk/white ...ohm it to a ground on the body .....if it registers your ground is good

 

one easy way to see if you're even getting that pulse from the ecm is to hook a test light up at your f/p relay connector. that would be to the green/white wire, can't remember what pin it is, but there's only one grn/wht. anyhow, ground the other end of the test light as you normally would. with the test light probe on that grn/wht pin, turn the key on. if it lights for a couple of seconds, then it's getting the signal from the ecm. if not, then you need to find out why. aside from that, supposedly the ecm will not operate the pump until it receives a signal from the diistributor (via the ignition module).

and i wouldn't mess with any grounds if you don't have to... i've got a ground issue right now that is kicking my butt. funny thing is, it's like the opposite of your problem - my f/p cycles with key on whenever i apply any kind of lights. how's that for being a wierd one?

 

sounds screwed up...thanks for the help...I am recieving 12V from the ECM...can someone tell me where the wire is under the car that runs to the FP...I am going to check to see if it is getting power to prime...its a 305 TPI. it seems that all of the wires that are coming from the relay are working fine. I guess it is between the relay and the FP...could the ignition module keep the fuel pump from priming when the key is turned on to the run position?
thanks thunderstick

 

The wires have a three pin weatherpack connector, and are located on the front drivers side of the gas tank. If you follow the lines coming out out of the tank, you will see the wiring by them (probably clipped to the lip of the tank). Three wires:

1-power for pump
2-ground
3-fuel gauge signal

 

Where are the wires in relation to the in line fuel filter by the tank...i can go from there. I know what wires you are talking about though. thanks

 

Follow the fuel lines from the inline filter back to the tank. Where the fuel lines go up and into the top of the tank is where the wiring for the fuel pump is located.

 

not 100% sure if the module will prevent the pump from priming, but i don't think so. i wouldn't worry myself with that one right now. i know the ecm will prime it, then i think it doesn't power it anymore until it receives the impulse from the module... but do what lo-tec said and check that connector - easiest way to check that wire right now. you may have a bad connector, or maybe corroded.

 

I see three wires that go into the top of the tank. I just cut a hole in my trunk and will weld it back in later. which wire does what and why is there three wires? I thought there was only one gray wire going back to the tank...according to this chiltons. thanks? btw, i think when it is cooler outside, it wont start...when it is cooler, the FP wont prime....when it is warm outside, it primes up and starts everytime....This could be just coincedential. I was also thinking about doing the FP Regulator and the Cold Start valve....do you think these could also be possibilites on why it wont start sometimes? if so, then how do i check them? thank you all so much.

 

also, how do I check to see if the harnesses are loose or worn or corroded...well, not corroded, thats a given...but would it be easy to install new harnesses that came with the FP?

 

please do not weld back .....short screws , pop rivits use a backing plate fire blanket somthing if you must weld

 

OK, not sure if this is right for your later model, but pretty sure it is. Feed power direct to pump from relay, tan and white stripe wire, to insure the control circuit is or isn't the problem. See picture and note the tan wire is on the front corner of the relay, just skin a short section and run a jumper to the battery: (sorry for the poor picture, look for a good sized tan and white stripe wire from the relay)

 

If still no go, you may have a bad connector inside the fuel tank, I've seen them black and charred, and like yours, will run a new pump for a couple days then quit. Kind of a poor setup for this I think, but anyway:

 

i had a similiar problem that my car woudlnt start because there was no power going from the relay to the pump,so i replace the relay, wasnt that either. turns out the ecm doesnt send a signal to the relay.all the wires on the realy were like splice, so i guess they touch by mistake and burn the shut down system.this is wat a auto electrition told me.but he's not if the late 80's gm car have a internal or external shut down system.so i ran a 12v ignition wire to the relay and ever since never had a problem