ColinOpseth

man.. this car is starting to tick me off.. since i've driven the car home from trading my '86 the car has seriously taken a dump on me..

while cranking one night after setting the TPS the car quit making fuel pressure.. i've cranked multiple times with no fuel pressure being built at the schrader valve on the fuel rail..

since then i've changed:
- fuel pump relay
- fuel pump relay plug including soldering connections
- installed new AC Delco EM241 fuel pump with strainer
- checked fuel pump fuse on passenger side of dash, it is fine

the car still cranks with no fuel pressure.. does anyone have a schematic of the fuel pump circuit? i'm thinking either the pump isn't getting power, or there's another switch/relay somewhere..

which wire do i probe on the fuel pump plug (the plug that comes out the top of the fuel pump casing on the rear deck).. also, did the '85 have a security system? i've noticed that when i open the door (never noticed before so i'm not sure) that the DIC flashes the SECURITY light on the main center panel.. should it do that with the doors open? it doesn't flash or light up during cranking..

i'm pretty sure it's not the fuel filter as i'm listening for the pump and hearing nothing.. am i missing something here? the harness is very butchered under the hood to the point that there are 6, yes, SIX wires that i have to install with the positive battery cables.. God.

help! :) :crazy:

bogus

are you sure the pump is running?

I would put a volt meter to the connector and see what you get.

it should be firing.

I am wondering if there is a big clog in the line, or a cut wire in the circuit.

I don't a schematic for that year... that is where I would start whilst waiting for one. Good luck!!!

ColinOpseth

thanks for the help, man..

i'm not sure which wires should be hot in the connector so i'm going to back-probe them all.. do you know how long those wires should be 'hot' after turning on the ignition?

i'm positive the pump isn't running, it's dead silent back there.. i'll try to round up a wiring schematic and then go from there.. :confused:

ColinOpseth

i have another idea, as well..

i want to test my old pump.. how best would i do that? just hook up two wires from a car battery to the terminals?

HighHopes85

Can be done that way. Make sure as much fuel is out of the pump as possible and make sure you use long leads so the electricity doesn't make a spark near the fuel.

Also in the 85, the priming circuit in the fuel pump is controlled by some kind of simple transistor. Mine fried on me. I hard-wired a prime switch in for a while. When I found out that the transistor was definately the prob, I scavenged a good transistor from one of my spare ECMs. Could be a problem there.

HighHopes85

Also, you can turn the fuel pump on through the ALDL port. Do a search on it, but it is something like applying 12 volts to pin G. DO NOT quote me on that though.

want2drivemy85

If you have a haynes manual, it will show you how to test the fuel pump. You will have to jump two wires at the fuel pump relay. That will bypass the relay and should supply power to your pump. If you pump is still not coming on, you might want to take it out and bench test it, like you are doing with your old pump. I have replaced the pump in my 85 twice in the past year, both times delco units, but the first only lasted 3 months. good luck........

snaketr

You are on the right track, you need to bypass the relay and test the pump. If it works the problem is most likely with your ECM. That is what controls the fuel pump. If you jump it and nothing happens you need to check and make sure you have power going into the the relay. If not you have a power supply problem, (the six wires) maybe, but get a wiring schematic. If the pump does not work in the test, there is your problem. Make sure you have continuity going from the wire in the harness at the relay to the power wire in the pump connector and that you have a good ground. If you do than your new pump could be bad, have seen it before. Make sure you use an AC Delco or maybe a Walbro.
Justin

h rocks

Colin, I didn't see anything in your post about replacing the fuel filter. If you have not, try that FIRST! Good luck and let us know so when you figure it out.

HighHopes85

FWIW...





-Matt-