D1 eating fuel pumps - what's the cause?

Tugela

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May 21, 2007
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In the past few months I have had two fuel pump failures on my 1998 D1 (AEL fuel system). Luckily I've had spares on hand so the inconvenience was minor. Today my wife was driving the truck and the engine stopped running at a traffic signal and wouldn't restart. Starter and all electrics are working. I'll check it out when I get home from work to see if it's the fuel pump again. All 3 fuel pumps installed have been correct AEL genuine LR parts. New fuel filter within the last 4,000 miles, fuse is fine.

One fuel pump failure, no surprise - they all have to go sometime. Two failures in a short time, maybe a coincidence. Three seems beyond chance. What other parts in the fueling system could be causing repeated pump failure? Other threads here suggest fuel pump wiring harness, CPS, or inertia switch. What's the best way to narrow down the possibilities? Where else should I look? Thanks for any suggestions.
 
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jymmiejamz

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Dec 5, 2004
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The crank sensor wouldn't likely be causing the problem, but the wiring to it might. I've never seen one of those old ones fail, only D2 CkPS fail in my experience. The fuel pump harness definitely can get corroded or melted. When it won't start, just check for power and ground at the fuel pump. If you have power and ground, but the pump doesn't run, it is just a bad pump.
 

Grenade

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Oct 8, 2015
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Possibly the brand/MFG? Not to familiar with the AEL stuff but does it require a special fuel pump or can you use anything that fits into the hanger? I've had good luch with AC Delco pumps.
 

Tugela

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May 21, 2007
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If you have power and ground, but the pump doesn't run, it is just a bad pump.

This is my point: it's extremely unlikely that I would end up with 3 consecutive faulty genuine AEL pumps in the span of a few months. My theory is that the fuel pump failure is not the root of the problem. It is the symptom of something else that causes the pumps to fail. I'd like to track down the more fundamental issue so I don't have to keep replacing fuel pumps at inopportune and frequent intervals.

I'll take a peek at the fuel pump harness, although the truck has been west coast its whole life and in 18 months of ownership I haven't seen any corrosion on it anywhere.
 

jymmiejamz

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I can't imagine anything actually causing the fuel pump to fail. I'm thinking more along the lines of something cutting the fuel pump off.
 

p m

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I don't remember if D1s have a fuel pump connector in the harness somewhere near the wheelwell like late Classics - I'd check that if there is one.

Besides that, how old is your fuel filter and does fuel pressure regulator work (on the fuel rail)?
 

robertf

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Jan 22, 2006
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High head pressure or starved supply are the obvious candidates. new sock filter and external fuel filter for each pump?
 

SMLE

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Aug 21, 2014
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Incorrect voltage to the pump causing premature failure?

Have you checked the voltage?
 

jymmiejamz

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I don't remember if D1s have a fuel pump connector in the harness somewhere near the wheelwell like late Classics - I'd check that if there is one.

Besides that, how old is your fuel filter and does fuel pressure regulator work (on the fuel rail)?

Pretty sure they do have that connector.
 

WaltNYC

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Mar 3, 2010
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When you say "fuel pump failure" does that mean no pressure at the rail or very low pressure?

Or what other method are you using to determine it is a non/poorly functioning pump?
 

Tugela

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May 21, 2007
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Here's what my investigations revealed last night:

1. Turning key to position 2: no sound from fuel pump. I put my ear against the load space floor while someone else turned the key.
2. Fuel pressure at rail: nothing. Depressed Schrader valve and not a single drop of fuel or any pressure released.
3. All fuses in engine compartment fuse box were intact.

It would seem that the engine died from fuel starvation, burning everything that was in the rail.

I don't have a multimeter to check voltage. However: the last two times this happened I replaced the fuel pump and the problem immediately resolved. So if there is a problem elsewhere it's not showing itself immediately upon fuel pump replacement. The last two fuel pumps died within a month or two. That's the weird thing and what I want to track down: what is causing premature failure of fuel pumps. Incorrect voltage or faulty relays seem like reasonable places to start.
 

robertf

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Jan 22, 2006
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Sounds like the fuel pump connector.

A multimeter good enough for automotive use is under 10 bucks at harbor freight
 

jymmiejamz

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I can't see how having the incorrect voltage would kill the pump unless your alternator was putting out way too much voltage, but even then you'd have other symptoms.

Get one of these at your local auto parts store or hardware store.
 

p m

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I can't see how having the incorrect voltage would kill the pump unless your alternator was putting out way too much voltage, but even then you'd have other symptoms.

Get one of these at your local auto parts store or hardware store.
I am not even sure the old pumps Nick discarded were dead - he could be restoring the connection on the pump during the swap.
 

fishEH

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Jan 26, 2009
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I am not even sure the old pumps Nick discarded were dead - he could be restoring the connection on the pump during the swap.

Exactly! Check the connection in the rear wheel well and at the pump. You could have corrosion or a loose comnection in one od of the plugs.
 

jymmiejamz

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I've definitely seen at least one Discovery come back to the dealership shortly after a fuel pump replacement due to the connector being melted slightly a the pump. Learning how to do some simple diagnostics with a volt meter can save you a lot of money and time.
 

Tugela

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May 21, 2007
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Seattle
Bringing some closure to the thread: new fuel pump wiring harness did the trick. Engine started right up. No problem with the fuel pump that was already in the truck. Ended up being a pretty easy job with a reasonably inexpensive part. If any other fuel system problems arise I'll update the thread.