anyone know where i can find the relay for the fuel pump??? My manual tells me it under the hood but the 3 that i have are for the AC, cooling fan, and fan motor (or something els to do with AC) I can see the wire go through the body back by the fuel tank, but it goes into the body and i lose it there. I feel stupid for asking because common sense would tell me it SHOULD be under the hood.

 

Fuel pump fuse maybe ?? I dont know where the relay is but the fuse I believe is next to the battery on the 305 and 350 motors / passenger side wall.

 

Ok, I just replaced mine about 3 weeks ago. . . It is indeed under the hood. On the driver's side firewall. But, mine was for a V6. . .

Not sure if this will be of use, but by going from a 1990 Chevy service manual, on the 5.0 V8, TBI the relay is in the middle there. The one on the left (that got cut off, sorry) is the Electronic Spark Control (ESC) Module. For the 5.0 TPI Its the same, just without the ESC. If this isn't helpful, maybe at least it'll get you on the right track.

 

It's the middle one....

 

funny thing is everything on my ride is backwards from what the pic shows, my alternator is on the other side and my coolant sensor is in the intake and not the head. but thanks I'm going to replace all three relays I have under the hood because all three are in different locations and I think one has been moved by a previous owner. That and I have my roommate who works for chevy seeing what kind of deal i can get to have them fix it. I've been troubleshooting this for a while now and I'm fed up and almost ready to sell my high school honey.


THANKS AGAIN GUYS.

 

Okay, after messing with it for a little bit this afternoon, my buddy who was helping me out was on something () when he felt the other relay click. Come to find out the middle relay that i have in the weird layout (2 on driver side, 1 pass side) is the fuel pump relay and the color wires I have are Orange (only hot 12v source), black/white (tested as good ground), grey is the feed to fuel pump, green/white wire (no juice or anything), and red wire (nothing as well). The fuse the is by the battery is good and so are all the ones under the dash (no fuel pump fuse, just INJ1, INJ2).

Anyone can help be much appreciated!!!!

 

http://www.austinthirdgen.org/index.php?pid=35
It's a short tech article on fuel pump circuit troubleshooting.
It'll help you pinpoint the source of the problem.

The black/white is ground. But do NOT short the green/white wire, it is NOT ground. You'll blow your ECM if you do.

Hope this helps.
Lou

 

Thanks for the help, it did help me out. I found out that when I hook up my test light with the key on, I only get juice on the orange one and the green one (only for 2 sec.) other than that no juice at the connector at the before it hits the sending unit, only a little more than 3 ohms for the pump and the connector is in good shape. tried jumping at the connector for the relay and my broher and I couln't hear the pump kick on.

Should there be a switched power source that goes to the relay to feed the grey wire(for the pump).

Thanks for the help.

Patrick

 

* See note below.

When you detect power at the GREEN wire it should (by design) be going through a small coil and eventually to ground. This causes the relay to 'actuate'. When the relay is 'actuated' then there will be a change in the contacts that the relay controls (you might hear the relay CLICK). In this case, when the relay is 'actuated' there will be a connection made between the GRAY wire and the ORANGE wire. Thus if you see a two second pulse of power to the GREEN wire it should 'cause' a two second connection between the GRAY wire and the ORANGE wire. If the ORANGE wire has +12 volts on it at this time then that +12 volts will be connected to the GRAY wire during that pulse period. The GRAY wire SHOULD reach the fuel pump if the wiring for the positive circuit if functional.

After the initial two second pulse you must turn the ignition OFF and wait (maybe) 5 to 10 seconds for the ECM de-energize. Then when you attempt the same experiment you should see another two second pulse of power being applied to the GREEN wire, thus you should also be able to detect a connection of +12 volts from the ORANGE wire to the GRAY wire for that same two second period.

When the relay is NOT energized, there is a 'default' connection that will exist between the GRAY wire and the RED wire (The red wire runs to your ALDL connector).

It is important to make sure that the GROUND that is used between the fuel pump and the NEGATIVE battery 'POST' is perfect. From what I understand the ground from the fuel pump does not travel DIRECTLY to the negative battery POST. It might travel from the fuel pump, through the external connector through the back seat sheet metal, to a grounding bolt under the rear seat behind the driver, through the CHASSIS, through grounding straps, to a ground cable, through the ground cable connector and then finally reach the negative battery POST. So you can see if you have a questionable connection anywhere in this sequence of connections that you will most likely have a problem with the fuel pump running efficiently (with full power) even though you have 12 volts reaching the pump on the +12 V wires.

* Since this might be read by others that do not have the same wire colors used by their fuel pump relay let me state this:

NOTE: The wires on your fuel pump relay might vary from those discussed here. Make sure you investigate manuals appropriate for your relay to find the appropriate colors used by the various contacts before experimenting.

 

Patrick, did the relay click when you saw the 2-second pulse on the green/white wire? If not, check the ground (black/white wire).

If there is full 12V between the green/white and black/white (for the two seconds) and the relay does not click, it sounds like a bad relay (or possibly oxidized contacts).

If you remove the relay and take a paperclip, you can connect the orange wire to the grey wire. The fuel pump should turn on.

Hope this helps.
Lou

 

Lou


The relay did click when i turned the ign. on, I will see what i get with the fluke after lunch. Thanks again for the help.

Patrick