Fuel pump starts, then shuts down - Defender Source
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  #1  
Old September 25th, 2015, 09:30 AM
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Stephen LeBlanc
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Fuel pump starts, then shuts down

Hi all. Something is going on with my fuel pump. I replaced it with a new one. Also replaced both relays under the dash (silver with brown line). I checked the pressure: 43-44 pounds. When I turn the key I can hear the fuel pump kick on, but then it shuts off as I try cranking the ignition.


Am I missing a relay? I double confirmed that it's not the inertia switch.


The truck starts right up using starter fluid.


Other notes:
-new injectors
-new fuel filter
-newer (preowned) ECU 14 CUX
-clean gas tank
-new relays (under dash ones)
-new fuel pump with good pressure (43-44 pounds)


What the heck am I missing?


Thanks in advance!


Stupid other question: It can't be the distributor, right? That got replaced too. Maybe I screwed that up? That might be a really really stupid question. But hey, this is a Defender, and NOTHING IS IMPOSSIBLE.
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  #2  
Old September 25th, 2015, 09:34 AM
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Bill Adams
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Yes, it is supposed to go into a prime cycle when you turn the key to RUN/ON. When you turn key to START fuel pump shuts off. When you release START after engine fires fuel pump is on again.
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  #3  
Old September 25th, 2015, 09:37 AM
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Stephen LeBlanc
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Quote:
Originally Posted by o2batsea View Post
Yes, it is supposed to go into a prime cycle when you turn the key to RUN/ON. When you turn key to START fuel pump shuts off. When you release START after engine fires fuel pump is on again.


Ok cool. So any thoughts as to why the truck isn't starting? Perhaps the lines need to be bled?
Note: the truck has been sitting for at least 5 years. However, starts right up with starter fluid.
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Old September 25th, 2015, 09:52 AM
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Mark Garrenton
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If it fires on starter fluid then you've eliminated the ignition. Are you using 5 year old fuel in the tank? If so there is most lies your problem. Where are you checking fuel pressure...at the Schrader valve on the fuel rail?
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  #5  
Old September 25th, 2015, 09:55 AM
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Stephen LeBlanc
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Quote:
Originally Posted by ezzzzzzz View Post
If it fires on starter fluid then you've eliminated the ignition. Are you using 5 year old fuel in the tank? If so there is most lies your problem. Where are you checking fuel pressure...at the Schrader valve on the fuel rail?

Thanks for contributing.

-new gas
-tank was removed and power washed to get old gas out.
-testing pressure at injector as my fuel rail does not have a Schrader valve.

So do people bleed/prime the lines? If so, how?

Thanks again!
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Old September 25th, 2015, 09:58 AM
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Mark Garrenton
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I'm guessing the CUX isn't firing the injectors. Are you hearing the click of the pintles opening?
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  #7  
Old September 25th, 2015, 10:00 AM
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Stephen LeBlanc
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Quote:
Originally Posted by ezzzzzzz View Post
I'm guessing the CUX isn't firing the injectors. Are you hearing the click of the pintles opening?

Crap...I just bought that thing. I'll check for the click. Man that's going to kill me if I need another one. I just bought this pre owned one. New ones are too rich for my blood.

Thanks again.
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  #8  
Old September 25th, 2015, 10:07 AM
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Mark Garrenton
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It doesn't mean the ECM is bad by default. There are a couple of relays required to make everything work too. I don't have a wiring diagram in front of me so I can't be of much more help.
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  #9  
Old September 25th, 2015, 10:09 AM
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Stephen LeBlanc
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Thanks for the advice Ezzzzzzz! Off to a good start.
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  #10  
Old September 25th, 2015, 11:30 AM
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Mason Worley
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You have a lot of good info here and I'm guessing that your looking at overload. I missed a little info. You said it purred when you started with ether? Did it continue on with fuel or just ether? When it run did you show a code? I believe the pintle being referred to to listen to I s the ones at the injector. Now this part is for confirm by the fellow owners. This being a truck with a distributor and not having a crank sensor. I think the ECU gets its signal to pulse the injectors(in batch fire) from the distributor. Are those wires present and accounted for? That's probably enough to chew on for a bit. The story continues...
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  #11  
Old September 26th, 2015, 05:21 PM
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Stephen LeBlanc
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Update: My mechanic is helping and thinks it has to do with pin #39 on the ECU. Does anyone have a wiring diagram?
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  #12  
Old September 27th, 2015, 08:32 AM
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Stephen LeBlanc
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Thanks for the PM! Diagram received. The hunt continues.
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  #13  
Old September 27th, 2015, 09:04 AM
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OK Stop using starting fluid any more. Use it as a diagnostic tool only. You know it will run on it, so now you've eliminated spark issues. So your problem is fuel.
The ECU is telling the pump to come on, so it's not the ECU. So the next item I would want to check is the fuel rail.
Thing one: undo the fuel supply connection at the back of the rail assembly. Key the switch (you'll need a helper) and observe the fuel flow. Should be nice and strong. Just blip the key so you don't gush fuel all over and pack paper towels under it to catch the spill. If that checks out then...
If not then you will want to begin with the fuel pump. It may be pumping but it may be clogged somewhere in the line. I assume you put in new fuel filter.
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  #14  
Old September 27th, 2015, 09:29 AM
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Quote:
Originally Posted by o2batsea View Post
The ECU is telling the pump to come on, so it's not the ECU. So the next item I would want to check is the fuel rail.
.

Thanks Bill. So are we sure we can rule out the ECU? It sends a signal at first, but the why no signal after we crank the key?

Also, I replaced the fuel rail as well, forgot about that when I drafted the list. Used but in much better shape than the original.

------ Follow up post added September 27th, 2015 09:34 AM ------

Quote:
Originally Posted by o2batsea View Post
If not then you will want to begin with the fuel pump. It may be pumping but it may be clogged somewhere in the line. I assume you put in new fuel filter.

Fuel pump replaced. 43-44 pounds of pressure. Nice spray at the injector end so my mechanic buddy is feeling good about the lines being good. Fuel pump shuts off after cranking key.

Yes new fuel filter too. So frustrating.

We also put a new Mallory distributor. Maybe we screwed up the wiring? Too many projects at the same time.
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Old September 27th, 2015, 09:39 AM
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Stephen LeBlanc
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Thanks again for all the guidance everyone. Really appreciated.
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  #16  
Old September 27th, 2015, 11:27 AM
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Quote:
Originally Posted by EnduroPro View Post

We also put a new Mallory distributor. Maybe we screwed up the wiring? Too many projects at the same time.
Lucas Law #3: Its always a mistake to change more than one thing at a time without proving that everything still works.
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  #17  
Old September 27th, 2015, 12:18 PM
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Stephen LeBlanc
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  #18  
Old September 27th, 2015, 12:26 PM
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Quote:
Originally Posted by EnduroPro View Post
Thanks Bill. So are we sure we can rule out the ECU? It sends a signal at first, but the why no signal after we crank the key?
.
because the engine has to start for the pump to keep running. It runs for 10 secs when key is first turned and then turns off till engine is running.

I recently had similar issue after swapping out an engine. If I gave the engine a small shot of ether
enough to get it to start then I could fool it and get the pump to run. In my case the pump was on its last legs and died later that day.
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Old September 28th, 2015, 08:29 AM
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Originally Posted by Uncle Douglas View Post
because the engine has to start for the pump to keep running. It runs for 10 secs when key is first turned and then turns off till engine is running. I recently had similar issue after swapping out an engine. If I gave the engine a small shot of ether enough to get it to start then I could fool it and get the pump to run. In my case the pump was on its last legs and died later that day.
The ECU enables the fuel pump if and only if it gets a pulse signal from the coil. It's a white wire with black tracer connected to the -ve side of the coil.
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  #20  
Old September 28th, 2015, 08:45 AM
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That white with black tracer may not look like much but it is absolutely critical to the operation of the engine. Be sure it is connected securely. Without it, nothing worky. It is not uncommon for the wire to fatigue and break right at the spade terminal. Seen more than one hanging on by literally one strand.
If it's not connected, the engine will not catch because the ECU still thinks it's not running. You will still hear the fuel pump go thru the prime cycle cz that is not tied to the engine firing and running. Once the ecu receives coil pulses for a certain period, then it starts the fuel pump.
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