On the electric lift pump on a 2004 for example, when they start to fail is it a
problem with the mechanical parts of the pump or the electric motor......

The pump mounted on the filter housing (not the in tank pumps)

I was just wondering if you monitored the current drawn with an amp meter
would you be able to detect a slow deterioration of the pump over time as it failed slowly and the output pressure dropped, or do these pump failures just happen very quickly and you have no low fuel pressure to the CP3.

In short would monitoring pump motor current draw show up problems developing in the pump????

Thanks

 

I think it's the motor that fails but I'm not sure. There is a very old thread that showed one cut open after failure. However, it's not very useful to try to predict it. You'll have to come up with some monitoring system that you think will show an approaching problem and then act on it before you get stuck. Just change it and be done. It will be working invisibly, and then suddenly you'll be stranded.

It's not "low" pressure it's blocked flow that stops the truck.

I recommend a Glacier Diesel Walbro setup. Do it at home now, on a weekend, instead of being towed to a dealer after being stranded and getting the in-tank setup for whatever they charge.

John

 

the design is asking for trouble I have never seen a pump that has to pull fuel 15 feet without burning up a pump pushes better than it pulls

 

yes its the little motor that is vibrating , pulling against a large suction head, and exposed to heat that fails. ditch that thing for a better aftermarket design before you're stranded.

 

You are on the right track..........the factory ecm does just that.Most failed pumps I see trip the code. If you are prepared a failed lift pump on a common rail will Not leave you stranded.
All you need is about 5ft of 3/8 fuel hose a couple of clamps an an inline filter.
You just bypass the oem filter/pump assy and the truck will restart and drive just fine to get you home.

Bob

 

Mine went all at once. I didn't know about the bypass trick. I ended up getting towed home.

 

Bob,

That's a good idea. No special fitting needed to replace the pump. Let the CP3 draw what it needs. Might be a little hard to get it bled.

I just went out and took my old lift pump apart to see what's up. This is the pump that replaced the one that failed and only has about 10,000-15,000 miles on it. Clearly the commutator in the motor is the weak link. Mine is worn at least 10% with only those few miles on it. It appears to be a non metalic material instead of the traditional bronze and very fast wearing. The pump section looks like it would last forever as long as it has fuel to keep it lubed. All hard steel and nicely made. It also is a very effective blockage when the not running. A vane type pump with roller vanes instead of a centrifugal type. I don't think it's a matter of too much suction head, just a poor quality commutator. There is also a very small opening on the suction end that could easily clog and an internal screen that is not possible to clean without sawing the pump apart. It cannot be backflushed because of the vane type pump and a check valve on the suction end.

Not a worthy design and needs an external strainer on the intake side!

Clearly, even my replacement pump would have failed before very long.

John