Bad fuel pump or something else?

[Shelbydaytona91]

Hey, STILL trying to get this Daytona running again. Looks like everything should be good. Up until about a week ago fuel pressure was always a happy 55psi at start and always primed up when I put the key to start. Now, I can not get the fuel pump to engage at all! Odd thing is I'll unplug the battery and let sit and it'll have 0psi for 3 days then randomly I'll check and it shoots up to ~40psi out of no where, no battery hooked up. Then I try to start and no fuel pump prime and runs a couple sec and dies. Psi back to 0. I just wondered if there is anything I can check before I drop the tank. Here's what I've done so far:

-Checked for spark incase it's ASD-> coil sparks
-Relay makes contact on key start position, although contacts are slightly worn
-Checked fuse
-ECU showing only fault 22
-Tried starting after and while banging the tank
- Clamping return line to see if pressure would build-> no effect

What I don't get is in the 4 years I've owned this car I've never had a fuel pump issue and then one day I hear nothing when I turn to start. Do they just die like this? I thought they get weaker and weaker then die or they would at least be intermittent.

[turbovanman²]

Check for power at the coil + terminal, if yes, which it should have as you have spark then do this-

Apply power to the coil + terminal, if the pump works and you have proper pressure, you have a wiring or connector issue, if not, you have a bad pump.

[Shelbydaytona91]

Apply power to the coil + terminal, if the pump works and you have proper pressure, you have a wiring or connector issue, if not, you have a bad pump.

Thanks for your quick response! I'm not sure I follow what you're saying to do though... Apply power from what to where on the coil? And when you say terminal, do you mean the plug on the bottom of the coil? Sorry if these are dumb questions!

[Dusty_Duster]

Thanks for your quick response! I'm not sure I follow what you're saying to do though... Apply power from what to where on the coil? And when you say terminal, do you mean the plug on the bottom of the coil? Sorry if these are dumb questions!

Take a wire, connect it to the positive battery terminal, and then touch the other end to the positive side of the coil. This bypasses the ASD relay and should cause your pump to turn on, unless the pump itself (or the connections) are shot.

[turbovanman²]

Take a wire, connect it to the positive battery terminal, and then touch the other end to the positive side of the coil. This bypasses the ASD relay and should cause your pump to turn on, unless the pump itself (or the connections) are shot.

Yep, what he said.

[Shelbydaytona91]

Ah ok that's what I figured I just wanted to double check before I mess something up. I'll give that a try and post the results.

[Shelbydaytona91]

I did just as described and disconnected the coil connector, ran a jumper cable between the positive terminal on the coil and the positive battery post. No change. Moved key to start position and no result either. And just to verify, the negative terminal on the coil is left open for this test with no jumper on it to the battery, correct?

[turbovanman²]

I did just as described and disconnected the coil connector, ran a jumper cable between the positive terminal on the coil and the positive battery post. No change. Moved key to start position and no result either. And just to verify, the negative terminal on the coil is left open for this test with no jumper on it to the battery, correct?

You don't remove any wiring from the coil-that was never mentioned, just simply turn the key OFF, apply 12 volts to the coil and see what happens. If you remove the coil wires, then no voltage can get to the pump.

[JohnnyIroc]

this is a 91 daytona?
unplug the connector at the bottom of the coil, stick the wire in the positive side i think its black with a green stripe and touch that to the positive side of the battery, you should hear the FP kick on

[Shelbydaytona91]

Yeah its a 91. I ended up getting a multimeter and the fuel pump plug showing 13v at start and the fuel pump is showing almost no resistance so I'm going to make a leap of faith and say the fuel pump is shot.

UPDATE: I pulled the pump and hooked it strait up to the battery and it didn't do anything. Definitely the pump. Thanks for the help guys!