my 86 N/A fuel pump only works when using a jumper on the 2 pin yellow primer. what would cause it to work only when primed?

 

that is the fuel priming connector. The MAF has a failsafe to kill power when there is no incoming air sensed. Also the fuel relay may be bad, as IIRC the priming connector is a wayaround the original relay... anyone?

 

Can someone point me in the direction of the Fuel pump relay??? I will give that a shot as well... cant hurt!

 

ok I did some major digging and found a relay under the dash with a yellow bottom I looked in my manual and its called "Fuel Injection Circuit Opening Relay" can someone explain EXACTLY what this does and if it should go bad what components WOULD NOT work? THanks love this forum so much information,

 

You got a BIG intake leak.
What did you do prior to this happening?
Did you mess with the air box or the intake manifold in any way???


-Ted

 

my car is having the same problem, pretty much. i dont know about his car, but my car just doesnt start, it cranks, comes alive for about a second, than dies back off.
hey 2ntenserex, why did you have to jump the fuel pump wires?? whats the reason for messin with it??

 

Please tell us how you determined the fuel pump does not work unless the fuel pump check relay is jumpered.

 

When you jumper that plug, you're giving a ground to the circuit opening relay. If the pump runs, then the relay is good...

You either have a bad AFM door switch, or a portion of the wiring in that area is bad...

 

That is is the Circuit Opening Relay. At the right front corner of the car is the fuel pump resistor.(behind the pass side head light) has a heat sink on it.
Here is a round-about way of cecking it. with the key on, remove the MAF
fome the air cleaner housing. push the door inside open(in direction of air flow)
You shold hear Circuit Opening Relay "click" and have power at fuel pump(back of car on drivers side under carpet and also under pannel)
If not trace ckt goes from MAF to COR to RESISTOR then to pump.
The reason for the resistor is the voltage is varied(less voltage at low rpms and more at higher) this u can see after the engine is running.
I HOPE THIS HELPS YOU.

 

I thought the jumper just bypasses the cut-out switch in the AFM?


-Ted

 

There is no Fuel Pump Resistor/Relay on a 1986 car. There is no heat sink. Period.

 

I mis-stated in my first reply. The yellow connector is the Fuel Pump Check Connetor. It bypasses the switch in the AFM. It puts a ground on the Circuit Opening Relay.

So the question remains......what makes you think the pump does not work?

 

Sorry "no resistor" Used to working on T2, Will post wiring diagram.

 

Sorry, won't have my brain in the up and locked position when posting about the Fuel Pump Check Connector. We're even, steven.

 

my wife drove car home from work next morning I go out and it just cranks and cranks without ever attempting to start not even a sputter. then I noticed I didnt hear the fuel pump like I normally do so I pulled the gas line going to the main rail and had her turn key on and nothing came out. Then I jumpered the primer and tried again I heard the pump come on and gas shot out the hose into the bucket I was holding to catch it in. so I took jumper out and tried again not even a drop came out. I had been wanting to put in a new pump anyways so I went and bought one and dropped it in. Did same test with hose off and same results, it works when jumpered and doesnt do squat when it isnt jumpered. so it cant be the connector back by the shock or the wiring up to there because it does work when jumped. It has to be something else - now when I pulled that yellow relay that I found under the dash and turned the key on it didnt do anything no clicking. which made me wonder if that was the problem. hope I explained a little better my situation.

 

here

 

so its gotta be the circuit opening relay that isnt opening when I turn the ignition on. right? it goes battery to main fuse to ignition to circuit opening relay to connector plug to pump itself. very cool thanks guys!!! I will post what fixed it when that happens hopefully tommorow.

 

I GOT THIS OFF ANOTHER WEBSITE: " The fuel pump is energized when the circuit opening relay's switch is in closed position. This is accomplished when the BR (brown) wire which goes to the Air Flow Meter (AFM) is grounded. When the AFM is operating (engine running), this BR wire is grounded. When the AFM is not operating (engine not running), this BR wire is not grounded and the fuel pump is not energized unless the fuel pump circuit terminal (yellow connector) is shorted with a jumper wire.


Having the fuel pump disabled when the engine is not running is a safety measure. This guarantees that the fuel supply is cut immediately when the engine is shut off whether it is intentional or not. The fuel pump circuit terminal (yellow connector) enables priming and testing of the fuel system without the engine running.

The fuel pump is not on when the ignition switch is at the ON position. It is on only when you crank, that is, the switch is at the START position. The fuel pump keeps on ticking if the car is actually started (air flows through the AFM).

Interesting tidbit: on a turbo 86-88, the actual voltage at the fuel pump is either the full voltage or a lower one. This is controlled by the "fuel pump relay and resistor" relay. By controlling the relay activation and therefore the bypassing of the resistor, the ECU can make the fuel pump operate either at full voltage or at a lower set voltage (to improve fuel economy). There is no such relay on the non turbo model. "

(Which Eroxx mentioned earlier and doesnt pertain to my N/A)

But you all definatly helped me in the right direction thanks to everyone man you guys rock shouldnt be a much sought after part at the junkyard going to try and snag me one today.

 

I missed something here. What part are you going to the junkyard to buy?????????

You know your pump works, you saw the gas.

You know the pump will hot work when the key is to ON.

You know the pump works only in START or the engine is running.

You didn't mention what happens when the key is held to START, whether the fuel came out the hoses or not.

You know the Circuti Opening Relay is good since when you jumpered the yellow check connector the fuel flowed.

It's early. I probably missed something important.

Anyway, you can see why I asked how you knew if the pumped worked or not.