Arrrgh!!! No fuel! - No fuel check terminal either???

[timkovo]

Hey guys, I been looking through all of the vfaqs, my shop manual, and the haynes and chiltons and I am in a bind!!!

No fuel pump activity. I gave the pump 12v a few days ago before I put the sending unit in the car and it whined just fine. All connecters hooked up, even changed the big relay under the dashboard.

This pic here, and my service manual say there is a single wire connected taped to the wireharness, behind/around the battery on the firewall. I cannot find this plug and I think I read on another forum that some 91's didnt have this terminal??? What can I do?

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I followed the instructions to test the relay, and the one I just got from the boneyard checked okay. Mine was shot, I could not get voltage on the right half. so I replaced it.

Next step is to check pin 10 on the harness under the ecu. I hooked the battery up, stuck my meter in pin 10, and grounded... waddya know. 12 volts. This relay checks okay.

Step 3. Find the hot wire that the fuel pump plugs into ( black wire/white stripe).
Plug voltmeter into there, ground... nothing.

So I am guessing some wire somewhere between that harness connecter and the fuel pump is bad... but I have no idea where to start looking.


Still cannot figure out why I don't have that check terminal.

 

[silver eclipse]

Not tryin to sound like a smart butt.

The fuel pump is on a relay, so if there is no power to the relay (key is not on) then there wont be voltage at the pump. Another thing is to check, im farely sure theres a fuse for the pump, or "fuel system" type fuse, make sure it isnt blown.
-Chad

 

[timkovo]

No... all of the tests were done with key in the "on" position.
MPI fuse is fine as well. All links in the fusable link on the positive terminal are fine.
I have no idea.

Are there any more fuseable components in the wiring for the fuel?

1. Big relay under the center console (bolted to the passenger side)
2. MPI fuse on the positive battery terminal.

-with all components plugged in, I get no voltage to the plug that the pump plugs into.

And I'll be damned if I got one of the lucky 91's that does not have the fuel check terminal.

here's one goofy idea...
Right now I don't have my isc plugged in(cuz i don't have one). I wonder if it checks for that first before letting the power go back there? I doubt it.

 

[timkovo]

Alright. Maybe this will help with the diagnosis.

Had a thought last night, and decided to pull the ecu out. Sure enough it has a funky smell to it. One of the caps is leaky.

Could the ECU having a leaky cap cause me no voltage at the fuel pump?

relay checks out okay. This is the only thing I can think of.

Any suggestions?
~Tim

 

[KeltonDSMer]

The fuel pump relay doesn't turn on until you crank the car, having the key to the "on" position will not do anything.

 

[timkovo]

Yea but shouldn't I be still getting 12v at the harness that the pump plugs into? I am able to apply 12v straight to the pump with a battery, and it kicks on. However, when I first turn the car on, I don't hear the "wirrrr" sound of the fuel pump priming. I took my volt meter to that plug and am getting zilch.

 

[boostedinaz]

The fuel pump relay doesn't turn on until you crank the car, having the key to the "on" position will not do anything.

So if the pump doesnt run in the "on" postion then how do any of us get around? The pump will run with the key in the "on" position.

 

[steve]

Because once the engine is running the ECU turns it's side of the MPI relay on.
Before the engine is running the fuel pump is driven off the starter circuit.
Look at the 1G MPI circuit diagrams.

2G's are slightly different because the changed to the MPI relay.

To rehash, on a 1G the fuel pump does not turn on until the ignition switch is in start.

Steve

 

[madhatter210]

Because once the engine is running the ECU turns it's side of the MPI relay on.
Before the engine is running the fuel pump is driven off the start circuit.
Look at the 1G MPI circuit diagrams.

2G's are slightly different because the changed to the MPI relay.

To rehash, on a 1G the fuel pump does not turn on until the ignition switch is in start.

Steve

My question would be then, so on a 1g the fuel system doesn't pressurize before it actually starts? It just seems like it would turn over a few extra revolutions before it saw fuel. Kinda like a a mechanical.

Yea but shouldn't I be still getting 12v at the harness that the pump plugs into? I am able to apply 12v straight to the pump with a battery, and it kicks on. However, when I first turn the car on, I don't hear the "wirrrr" sound of the fuel pump priming. I took my volt meter to that plug and am getting zilch.

I take it the system worked before the old fuel pump died so if your not finding the "wire" thats supposed to be there maybe yours just doesn't have it.

Try testing the wire before the plug, it is possible that during removal the connections inside the plug were moved and or seperated from the ends. Either way you need to test from the front and work your way back or vis versa till you find the issue.

In my opinion though when theres a problem and you know its messed up some where, its almost always easier to run new lines back from the relay and to redo the harness. Or better yet though it may seem not ideal, it would relieve alot of stressfull "short finding by running a new wire from a good 12v source and adding a fuel pump off/on switch and running back from there to the new pump.

 

[steve]

My question would be then, so on a 1g the fuel system doesn't pressurize before it actually starts? It just seems like it would turn over a few extra revolutions before it saw fuel. Kinda like a a mechanical.

Sure there is a small amount of time between when you turn the key to start and when the starter starts spinning the engine that counts as priming. You'll note that if the fuel system has had time to bleed down the engine might not start quite as fast as when the system is up to pressure.


timkovo, there is a TSB out from way back in time alerting dealers that some '91 cars don't have a fuel pump check connector. Mine doesn't either.

You can turn the pump on with MMCd or other dataloggers.

Steve

 

[92awddsm]

According to your first post, Im assuming you just recently installed the fuel pump, correct? And you say that you heard the pump whir during the preinstall test and after install, right? Well, you do know that the o-ring on the pump will tear or #### while reinstalling it into the pickup assembly, dont you? It is a fairly common problem so I would check that first. If it is the problem, a piece of 3/8 fuel line can be used as a replacement and works much better. Check it and let us know.

 

[timkovo]

According to your first post, Im assuming you just recently installed the fuel pump, correct? And you say that you heard the pump whir during the preinstall test and after install, right? Well, you do know that the o-ring on the pump will tear or #### while reinstalling it into the pickup assembly, dont you? It is a fairly common problem so I would check that first. If it is the problem, a piece of 3/8 fuel line can be used as a replacement and works much better. Check it and let us know.

I took a battery and put 12v to the pump. Just to test it to make sure it works. I put another tank/sending unit/pump into my 91 due to my other one being rusted to hell and back.

Wal190 already installed in the sending unit. Didn't have to worry bout it.

I can take a spare battery, and put a probe on the sending unit side of the plug, put 12v to the black/white wire, and ground it, and the pump will kick on.

But on the other side of the plug (the one that is connected to the bottom of the trunk... I get no juice.

**SIDE NOTE***
I was planning on doing the rewire as per the vfaq, but the only thing that is on my mind, if I can get a 12v source back there, and as I am not getting any power it seems to that whole plug, won;'t that also mean that my gas guage wont work as a result too?


Thanks for all the replies guys.

 

[1gTurboTuner]

I dont know if this will help or not but here goes...

I recently installed a new motor but didnt touch the fuel pump or anything and we finally get the motor in and like you said me and my dad could not here the wirr of the fuel pump so we checked the filter nothin.... we just cranked the car over for quite a while like 3 min in all?? (maybe a little more) and checked the fuel pump again and it had plenty of fuel pressure and it fired right up.

So have you tried just cranking it over for a while? check the fuel filter to see if you got pressure maybe its not electrical at all.

sorry if this is just some dumb high school kid pointing out the obviouse that you already did good luck

allan

 

[timkovo]

I dont know if this will help or not but here goes...

I recently installed a new motor but didnt touch the fuel pump or anything and we finally get the motor in and like you said me and my dad could not here the wirr of the fuel pump so we checked the filter nothin.... we just cranked the car over for quite a while like 3 min in all?? (maybe a little more) and checked the fuel pump again and it had plenty of fuel pressure and it fired right up.

So have you tried just cranking it over for a while? check the fuel filter to see if you got pressure maybe its not electrical at all.

sorry if this is just some dumb high school kid pointing out the obviouse that you already did good luck

allan

Honestly I did not do that.....the reason I did not do that was because my shop manual and service manual both talked of the "whirring" sound of the pump when the key was turned to on. Since I never heard the "whirr" sound, I never attempted to start the car.

I gotta fix a fuel leak first. Then I am going to try that. Last night when I applied voltage straight to the pump, fuel was dripping on the other end of the high pressure line off the pump housing. Gonna fix that tomorrow (not tonite due to me being sick as hell). After I get the line fixed, I'll give it a try and be sure to post the results.

 

[timkovo]

Well, 1gTurboTuner!!!!!

That worked! Hooked that battery up to it, connected the jumper cables.
Gave her a good crankin, and what do you know when I let off the key, I heard the pump!!
It's pumping alright.... but I got a nice leak on the far end of the high pressure hose that connects to the line that is on the frame.

Gotta hope I can fix that. Maybe I just didn't tighten it down good enough (HOPES)

Thanks for all the help guys!!!!

~Tim

 

[timkovo]

Well I spoke too soon.....the fitting wasn't loose... the dang hardline got a crack in it. Its not in the easiest spot either.

Any suggestions?