Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Fuel pump relay and fuse location on 91 K5

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 5.0THIS, Sep 10, 2002.

  1. 5.0THIS

    5.0THIS Registered Member

    Joined:
    Apr 3, 2002
    Posts:
    13
    Likes Received:
    0
    Location:
    Louisville, CO
    Recently my 91 K5 wouldnt start, so the first thing I did was spray some starting fluid down into the TB, and it fired right off, so I know it's fuel related. I cant hear the pump running in the tank, but before I go dropping the tank I want to check the electrical first. I have not been able to locate the fuel pump fuse and relay, could anyone help me out here on their locations, thanks very much

    Andy
     
  2. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    The fuel pump relay is mounted on the firewall, just to the passenger side of the engine. It's oval shaped when looking from the top of it. But if you can hear the pump kicking on when you turn on the key, then the relay is working. /forums/images/icons/frown.gif So check first for fuel pressure. Also check to make sure that the fuses for the injectors are good. They're located in the fusebox under the dash.
     
  3. 5.0THIS

    5.0THIS Registered Member

    Joined:
    Apr 3, 2002
    Posts:
    13
    Likes Received:
    0
    Location:
    Louisville, CO
    I see the relay.... is there any way to test it before simply replacing it? Also, I cannot locate the fuel injector fuse in the fuse block just above and to the left of the brake pedal? any thoughts?
     
  4. 5.0THIS

    5.0THIS Registered Member

    Joined:
    Apr 3, 2002
    Posts:
    13
    Likes Received:
    0
    Location:
    Louisville, CO
    Ok... I found the fuel pump fuse, over mounted on the heater core near the passenger front fender, a 5A fuse, which was ok. the relay is pretty cheap, I suppose I'll give that a try first. if that isnt it, I have heard these vehicles have a fuel pump inertia swtich, or an oil pressure switch, that might also shut the pump down. Anbody?
     
  5. Sandhills Blazer

    Sandhills Blazer Registered Member

    Joined:
    Nov 6, 2001
    Posts:
    45
    Likes Received:
    0
    Location:
    South Carolina
    Before you go out and buy the relay. Have a friend get in and attempt to start the vehicle and while he does that take a big rubber mallet and knock the you know what out of the bottom of the fuel tank. If the pumps bad it will start up about 90% of the time. If it does not start it could still be the pump. No start, then take a chance on the relay. I just went through this on my 91 K5. It's not too bad. Just takes time.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,976
    Likes Received:
    189
    Location:
    Roy WA
    As I recall my wiring, they use a relay, as well as an oil pressure switch. I *think* if the oil pressure raises (such as extended cranking) even if the relay has failed, it will still start. So if thats true, which I think it is, then if the oil pressure switch is "seeing" no oil pressure, the pump won't work.

    Relay itself should be fairly easy to test, when one of the small wires gets 12V, (such as key to "run") the switch closes(? proper term?) and 12V "flows through" the relay. One big wire is the 12V "in", and one is 12V "out", basically one big wire is 12V battery, and one is 12V to whatever accessory is being run.

    At least thats my understanding of it.

    You do know there is a fuel pump terminal on the ALDL connector, right?
     
  7. 5.0THIS

    5.0THIS Registered Member

    Joined:
    Apr 3, 2002
    Posts:
    13
    Likes Received:
    0
    Location:
    Louisville, CO
    Well, it isnt the relay, it's not the fuse, so it's either the oil pressure switch or the fuel pump. Guess it's time to start dropping the tank and do the pump, any tips anybody? /forums/images/icons/smirk.gif
     

Share This Page