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Should fuel pump be pumping while starter is turning?

fuel systemfuel pump

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13 replies to this topic

#1 Ofeargall

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Posted 12 August 2013 - 11:49 PM

I was driving to work this morning and the engine on my 89 GL wagon just died. I pulled over and checked the timing belts which I recently replaced. Fortunately I removed the covers so I could clearly see they were fine. I tried to start the car, it ran for a moment, sputtered and died. Tried again and it sputtered momentarily then wouldn't start again.

 

I pulled the fuel pump panel and disconnected the fuel line on the exit side of the pump where it connects to the line leading up to the engine compartment *after* the little check valve. A little fuel dribbled out of the line that feeds up to the engine compartment but nothing from the fuel pump side.

 

I know there's fuel in the tank.

 

With the fuel line disconnected on the output side of the pump I had my wife turn the engine over but no fuel came out of the pump.

 

Is this normal behavior or does the pump only operate when the vehicle is actually running?

 

Do these fuel pumps fail somewhat regularly?

 

Any help is appreciated.



#2 NorthWet

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Posted 13 August 2013 - 01:39 AM

Is yours carb'd of SPFI?  (Brain won't let me remember if carb was offered in 89.)

 

For SPFI (and at least partly for carb):  The fuel pump is set to run for a few seconds (5??) when you turn your key from ACC to ON.  It then tuns off until it gets a signal from the ignition system that  the engine is rotating.  I don't recall the starter circuit being energized affecting the pump's power.

 

IF yours is not a carb, connecting the green diagnostic connectors (SPFI: near wiper motor) will cause the fuel pump to cycle on every few seconds, whcih should allow you to check the pump.



#3 Ofeargall

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Posted 13 August 2013 - 07:28 AM

So there's a green diagnostic wire that's disconnected near the wiper motor on the firewall? Who knew?!

It is SPFI, sorry I failed to mention that.

Thank you!

#4 NorthWet

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Posted 13 August 2013 - 10:23 AM

The connector should ONLY be connected for diagnostic purposes:  pulling error codes, setting timing, forcing the fuel pump to cycle.  If left connected, it will hold the ignition timing static, preventing the ECU from varying the timing as needed and making your engine run badly above idle.


Edited by NorthWet, 13 August 2013 - 10:24 AM.


#5 BoxerRebellion

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Posted 13 August 2013 - 11:21 AM

If I'm not mistaken, yes.

Coud be mistaken...

 

However, initially turning the key to ON - you hear that "vroooooo" and then it stops.

 

Priming.

 

Gotta have at least a little fuel ready for the injectors to do their thing when they're told to do it.



#6 robm

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Posted 13 August 2013 - 11:23 AM

It may be the fuel pump relay.  It is one of the relays under the dashboard, above the fuse box.  An absolute pain to get to. It may also be a bad transistor on the ECM, the one that turns on the pump relay.

 

Use the green connectors to diagnose the problem.  Connect, and turn on the ignition, but don't start the car.  You should hear the fuel pump running every few seconds, and the relay clicking under the dash.

 

If you hear the relay, but not the pump, it is probably a pump problem.

 

If you don't hear the relay or the pump, check the relay first.  Just swap a nearby relay into the same position, and see if it helps.  These relays seem to get flaky after 20 years or so. 

 

If swapping in a new relay doesn't help, it may be the ECM transistor.  There is an excellent post on troubleshooting and fixing this problem if you search on here hard enough. 

 

I had this problem, and discovered the relay was heat sensitive.  It would work fine in the cool of the day, but would crap out when it got hot, or if I turned on the heat in the winter. I had the same problem with the blower relay (which is the same kind of relay), that would fail in the winter when the heat was on.    Intermittents like this are very hard to deal with.  I finally changed out the relay, but didn't get a chance to drive it long enough to find out if this was the final fix.



#7 Ofeargall

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Posted 13 August 2013 - 07:39 PM

Thanks gang. I'll be arriving at the roadside resting place of the car shortly and see what I can decipher.

#8 Ofeargall

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Posted 13 August 2013 - 09:35 PM

Okay, stopped at the rig on my way home. Connecting the bright green leads produced a rhythmic clicking from under the dash and in the engine compartment. The pump is hanging under the car by the fuel line and doesn't even twitch when the relay clicks. I put my hand on the pump and its not doing anything.

I'm headed back with a volt meter to see if the electricity is even making it to the connectors but it sounds like a bad pump. Anyone for a spare in Monmouth Oregon? ;-)

#9 Ofeargall

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Posted 16 August 2013 - 09:39 AM

Quick question on this thread regarding the fuel pump. I'm seeing them on eBay go for anywhere between $65 and $275+. Any insight on which one will get the job done economically?



#10 NorthWet

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Posted 16 August 2013 - 11:13 AM

If you are close enough to Portland to make it worth it, there are/were several pull-it-yourself junk yards where you could grab a used one for cheap.  Otherwise, there is an inline pump for a Ford F150 that you can get new for around $40 that is supposed to work well.

 

I should have suggested that you take a battery and some wire and directly apply power and ground to the pump to insure that it is dead.  The connector is right there at the pump, and polarity won't matter for testing for life.



#11 ruparts

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Posted 16 August 2013 - 11:56 AM

Okay, stopped at the rig on my way home. Connecting the bright green leads produced a rhythmic clicking from under the dash and in the engine compartment. The pump is hanging under the car by the fuel line and doesn't even twitch when the relay clicks. I put my hand on the pump and its not doing anything.

I'm headed back with a volt meter to see if the electricity is even making it to the connectors but it sounds like a bad pump. Anyone for a spare in Monmouth Oregon? ;-)

 

 Hi, 

  the ground side of the fuel pump circuit is done inside the ECM,, i've had them quit working and only needed to repair the ground.  you can make it ground  to the body near the pump for a simple fix.   not saying this is it but could save you the cost of a pump if it is.  and if it is the new pump won't work either . 



#12 robm

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Posted 16 August 2013 - 03:12 PM

I am sorry, the fuel pump does NOT ground through the ECM.  The ECM triggers a relay under the dash, which fires the pump.  If you put a continuity checker on the black wire of the pump, you will find that the pump is always grounded.  A wire direct from the battery to the red wire on the pump will run the pump.  I don't know where it does ground.  The fact that grounding it near the pump works proves that the ECM doesn't have much to do with it.

 

The ECM does ground the coil of the relay to fire it, but that is a whole different thing.

 

I fought a flaky pump relay for months.  I know this system intimately.

 

I agree with the idea to run a wire direct from the battery to the red wire on the pump.  I suspect the relay contacts get flaky, so clicking may not tell you what is really happening.  The relay pulls in, but doesn't actually connect its contacts.


Edited by robm, 16 August 2013 - 03:18 PM.


#13 Gloyale

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Posted 17 August 2013 - 04:42 PM

I am sorry, the fuel pump does NOT ground through the ECM.  The ECM triggers a relay under the dash, which fires the pump.  If you put a continuity checker on the black wire of the pump, you will find that the pump is always grounded.  A wire direct from the battery to the red wire on the pump will run the pump.  I don't know where it does ground.  The fact that grounding it near the pump works proves that the ECM doesn't have much to do with it.

 

The ECM does ground the coil of the relay to fire it, but that is a whole different thing.

 

I fought a flaky pump relay for months.  I know this system intimately.

 

87+ MPFI models DO ground the pump through the ECU.

 

The relay is on the 12v side, and is triggered on by the ECU through pin 6. It does control the ground side of the relay. However, this is not the ground side of the pump.

 

The ground wire for the pump itself is shielded, and runs all the way back to the ECU, pin 55.

 

I have dealt with this on EJ swaps into MPFI cars where a ground wire must be provided to the Fuel pump.

 

 

SPFI and carbed models ground the pump to the body. So that's not likely his problem. 

 

I suspect the relay.

 

I'm in Corvallis barely 30 mins away and I've got a few pumps I could part wtih one.


Edited by Gloyale, 17 August 2013 - 04:47 PM.


#14 Ofeargall

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Posted 11 December 2013 - 05:33 PM

Just to close out this thread, the fuel pump was indeed dead. I picked up a used one from Pick-A-Part in Turner, Oregon, put it in place and was back on the road in minutes. Hooking the bright green leads together under the hood to trigger the pump and then testing the leads at the fuel pump with my multimeter confirmed that the pump was definitely getting voltage, whereby I deduced the pump to be the problem. Thanks for that tip on the green connectors!






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