That's just it....I don't know what I could have wired wrong. When I wire it directly to the battery, it pumps great. I pulled the pump again today and put my test light right on the connector to the pump and it lights up for 3 seconds, but still wont pump when wired through the relay.

 

Check the ground. Will the car start with the pump short wired?

 

The coolant sensor on the front of the block can shut down the pump also.

 

Lets see if we can figure this out.

First is the fuel pump fuse okay? Are the injector fuses okay? Regardless pull the fuel pump fuse and put it back in or replace it.

Turn the key to on but don't start the car. Is the engine light on and is it steady?

Turn the key to on again. Do you hear the pump kick in for 2 seconds? Very important..listen.

Right after you hear the pump turn on for 2 seconds do you hear a noise from the injectors for two seconds?

Answer the above first.

Jim

 

I assume you you mean by short wired, directly to the battery? Yes, I wired it directly and the car started and ran great.

How do you check the ground??

 

Pulled both fuses (one by battery and one in box), one looked questionable and got replaced.

I assume the injectors and fuses are fine as I did get it started by wiring the pump to the battery and it ran fine.

Yes, the engine light is on steady.

No, but I do hear the pump relay click on and off at about 2 seconds, but no pump.

I hear the injectors buzzing.

 

Not a click. Do you actually hear the pump turn on for 2 seconds...it will be an buzzing sound.
Interesting that you hear the injectors. Thats the prime pulse. Can you take the cleaner off and next time watch the injectors. when you hear the sound from the injectors do you see a squirt of fuel. It should only be for a split second.

 

The fuses I am talking about are in the fuese panel. Two are labeled Inj and one is labeled FP.

Check for power like you have been. Then pull the FP fuse and check for power. There should be none. Lets elliminate a short.

 

No, the pump doesn't buzz. No squirt from the injectors. Only a buzzing noise from the injector for a split second, but no squirt.

 

I think the injectors are working fine. When I wire the pump directly to the battery, the the car runs fine and they squirt fuel.

I will check the FP fuse and get back to you. You are talking about the one in the box right?

Can you tell me how to check the ground to the pump? I am wondering if it may be that.

 

I do mean the fuse in the panel.

Sounds like wiring issue. I'll look in the manual

 

You probably have one ground wrong. The shaft has to be grounded too.

 

OK. I have some new info. I pulled the pump just so I could see better what is going on.

There are three wires coming out of the pump unit. A black one that is soldered to the unit (ground?), a orange/pink one (that i assume to be for the gauge?), and a light grey one (hot wire?)

Ok, I wired the hot wire through the system (relay, ect) and grounded the black wire directly to the frame of the car. The pump started and ran for two seconds just like it is susposed to. So, I a deducting that it has to be a grounding issue, right? Now what?!

 

Looking at the diagram. It looks like the ECM must receive confirmation that they system is grounded.

I think you need one ground to go to the pump and one to go to the shaft.

Exactly how many wires do you have? Earlier you said you twinned together two blacks and ran them straight to the pump. I think you need to run one of those wires to the shaft.

Maybe a test that will work. Run a ground from the battery and touch the top of the fuel pump assembel. anywhere near the gas filler and see if that works.

 

This may help. Taken from another forum. Just out of curiousity why did you change the fuel pump? You do realize the oil pressure sensor failing will cause a no fuel problem.

You will see that there is a:

TAN/WHITE wire on A that goes to the Fuel Pump Fuse then to the Fuel pump, Oil Pressure Switch. and Pin 17 on ECM Connector C451 (+12V Relay Switched).

BLACK/WHITE wire on B that goes to Ground, and 2 pins (6 & 12) on the ECM Connector C451.

DARK GREEN/WHITE wire on C that goes to pin 18 on ECM connector C451. (Fuel Pump Relay Drive).

RED wire on D that goes to the Diagnostic Connector(under ash tray).

ORANGE wire on E that goes to the Battery, Oil Pressure Switch, Pins 10 and 15 on ECM connector C451 (+12V Battery).

So here's the order that things happen in the circuit:

!) Ignition switch is turned on. The ECM sends a signal to activate the fuel pump on Relay connection "C", with a return ground on "B". The relay closes output contacts "A and "E" which sends +12V to the fuel pump fuse, through it and to the Fuel Pump, and starts the fuel pump.
The fuel pump runs until the pressure comes up in the fuel system then shuts off. (Note:The fuel Pump shuts off by itself, not because the relay did. It has a pressure sensor in it and the relay is still on).

2) The "C" input will stay energized (Closing "A" and "E" contacts) while the engine is cranking until it starts.

3) Once the engine starts, the Oil Pressure Switch closes a set of contacts that short the "A" and "E" wires together, essentially bypassing the Fuel Pump Relay as long as the engine is running unless you experience a loss of oil pressure, or the ignition is turned off.

So the Fuel Pump Relay only works during the starting and cranking phase of the cycle. Once the engine has started, it turns off and the fuel pump is kept on by the Oil Pressure Switch (that black cylinder thing with the 3-wire connector on the engine block ) next to the distributor.

 

But if the oil pressure switch just powers the pump after startup, it shouldn't have anything to do with the initial pumping when the key is turned on right? Unless the ground runs through it....

I changed the pump because it seemed like the easiest first troubleshooting step. It probably wasn't the problem looking back. Since it started right up when I looked at it, I just figured the pump had went out between then and now. I wonder if the guy I bought it from had the same problem and had just jury rigged it for my visit.

I looked closely at the pump assembley and here is what I see. There is a black wire coming out of the pump and is soldered to the shaft. Then there is another black wire soldered to the very top of the assenbly by the fuel cap that goes to the ground wire. The grey wire coming out of the pump goes to some sort of small resistor or capsitor then out to the top of the assembly to the hot wire. I think the pump itself is wired correctly.

I am loosing ground somewhere between the relay (I tested the ground right out of the relay and it is good) and where the ground wire leaves the cab to go to the tank. I am assuming this could be in the ECM, the oil pressure switch, the coolant sensor, or any other place in between. It's driving me crazy because I have no idea where it could be! I guess the next step is tracing the ground wire back and through the system. I just think is is soo confusing once you get to the main wiring harnesses since there are so many wires.

 

Look at the diagram on the link I sent you. I think the black goes into the ECM first.

The pump does not stay on all the time. It primes the system then goes off . It only goes on periodically to keep the system pressurized.

You are not getting a prime pulse. You said you hear the injectors but don't hear the pump. On the other hand you said when you turn the key to on you get power at the pump for 3 seconds. If you are getting power for 3 seconds why can't you hear the pump for 3 seconds?

You are right when you say the oil pressure sensor only kicks in afterwards unless it's stick in the kill position. Got to it and Jump it and see what happens. You should have power in on the red and power out on the Tan/white strip. Use your test light...ground the black to the car any where and probe the red then turn the key to on and probe the tan/white wire.

The one other time I had this happen was a fault in the distributor. The wires coming out of it on the driver side give the ECM a reference. If the connection is loss it may create the problem.

I have also heard people say the wires going in on the passenger side of the distributor were broken under the cap when this problem occurred.

See if the car starts by pouring gas into each throttle body.

The car should also start if you hook up the power to the pump and disconnect the power before you turn the key. Once the system is primed it should start and run until all the gas is gone from the system. If it does start and stops running as discribed something is not powering up the pump after start up. If you happen to get it running this way see if the engine light goes out.

 

Just curious but where is the fuel pump relay you hear click? You are testing and hearing the relay buried in front of the ECM right?

 

I put my test light on the hot wire right before the pump and turned the key.....light came on for 3 secs, then off.....the pump didn't turn on. That is with both wires wired through the system. Then, when I wired the ground to the frame, the pump works. That is why I think it is something with the ground.

The car does start, I already tried the gas in the throttle body thing and it starts right up. When I prime gas by running the pump for a few seconds, the car starts up and runs until the gas in the system is used up.

 

Neither the ECM and the relay are mounted to the car, just loose connected the the wires. I popped the cap off the relay and can physically see the relay working when I turn the key.