Just fried my 2nd fuel pump. Why?

[EastAustinSawdust]

Alright so I've got a bit of a history with fuel pump problems. I have a Mallory Series 110 fed by a Revolution Electronics relay. The relay turns the pump on for 3 seconds and then off unless the engine is running.

Anywho, the pump shorted out. Again.

The last time this happened (see this thread) I put in a heat shield between the pump and the exhaust. Per feedback from others, I was thinking the exhaust heat might be cooking the electronics in the pump. Well, either the heat shield didn't do it's job, or there's another problem.

I just installed a new, much cheaper pump and everything works fine again. At least if I fry it again I won't be out $150+.

 

[dvdswan]

Do you have a filter between the tank and pump? I know the 110 has a internal regulator but some applications need an external as well.

 

[Dave M]

Are you running the pump power supply directly through the controller, or to a seperate pump relay, to avoid any possible voltage/current issues.

 

[EastAustinSawdust]

Do you have a filter between the tank and pump?

I do, and the filter looked clean enough but the insert was a bit sucked in. See picture. Did I misread this? Is this what a dirty filter looks like? Was I starving the pump?

 

[EastAustinSawdust]

Are you running the pump power supply directly through the controller, or to a seperate pump relay, to avoid any possible voltage/current issues.

Hmm…the pump controller I have is a relay designed to supply power directly to the pump. Are you suggesting there should be another relay between the controller and the pump?

 

[AyWoSch Motors]

I bet you have a partially kinked fuel line or hose.
The pump is pulling fuel like it should, but it's trying extra hard because of a restriction and therefore prematurely failing.

 

[Camar068]

just me but I'd get the pump away from anything hot....and run dedicated wire to it. How does the relay know the engine is running?

 

[Dave M]

Hmm…the pump controller I have is a relay designed to supply power directly to the pump. Are you suggesting there should be another relay between the controller and the pump?

Yes, but it's just a personal choice as I imagine a relay would have a better set of electrical contacts for the pump motor. The relay coil itself is not going to draw as much amperage through the pump controller module.

 

[SirRobyn0]

Here is my take. Aftermarket electric pumps tend to be a bit problematic. One thing. The filter before the pump, your kind of damned if you do and damned if you don't, if you do and the filter clogs up you can starve for gas or fry the pump. If you don't run a filter you might suck something into the pump that does damage.

Have you ever had the tank out of the truck? I ask for two reasons one is to find out how clean it is inside, but also from the factory there was a sock at the end of the pick up tube in the tank, if it's a bit clogged up it could cause excessive suction damaging your pumps and collapse that filter.

Now that filter doesn't look dirty to me, but it is collapsed for sure. Something happened, either it's not drawing gas freely from the tank or that filter element was defective.

If it was me I'd order a new sock for the pick up tube, sometimes comes with a new sending unit. Drop the tank, if it's dirty clean it out if it's rusty replace it. There are ways to clean up rusty tanks, but a new 20 gallon saddle tank (if that's what your running) is only about $100, and you'll be ahead both in time and money vs trying to seal out rust IMO. I don't know the details on your fuel system so I might be going a bit overboard but you can just pick out the useful info.

So I'd get my tanks clean as a whistle with new socks in them and eliminate that filter before the pump. As I'm sure you know electric pumps don't like to draw though to much resistance, and that is one of the reasons new vehicles have them in the tank. On that same note I would replace all the rubber line from the tank to the pump unless it is already new just to eliminate any issues with that as well.

As long as the pump is not getting hot from the exhaust, in other words the shield is doing it's job I would not worry about that.

As long as you are running appropriate gauge wiring and have a good ground I don't think electrical is your issue. I've seen some pretty cheesey electrical setups on pumps that lived a good long life, but that's just my opinion.

 

[Bextreme04]

Another thing to consider is that the filter before the pump, if you choose to run one, should be a very coarse filter. You want as little restriction as possible as the inline external pumps are meant to push fuel, not pull it. You should have nothing finer than 100 micron before the pump and the smaller 15-30 micron filter after the pump and before the fuel rail or carb depending on what you are running.

 

[Grumpy]

In addition to SirRobyn0, I would also add some extra ground straps wherever possible. Check for high resistance in the power circuits, as low feed will cause any electrical parts to fail early.

edit: I have only seen one example of too many grounds. Years ago, while diagnosing an issue with a monitor on an agricultural tractor, the factory representative suggested the farmer drag a chain behind the cultivator to improve the grounding of the sensors......... and what about the thirty-two shanks already dug into the dirt?

 

[EastAustinSawdust]

Thanks for all the advice! I know for a fact that the lines from the tank to the pump have seen better days. I’ve never dropped the tank and it’s been on my todo list, so I’ll probably bump that up in priority.

 

[SirRobyn0]

AFAIK the tank sock isn't really available though parts stores unless you buy a sending unit, at least I know Spectra sending units come with them. Jegs has them for something like $5. According to what I have in my notes it's part #555-78538 you might consider having one on hand for when you drop the tank. And please let us know what you find!

 

[Rusty Nail]

Dude!
Your filter ....

It's sucked itself to death.
That is BADASS!
Great pik.
Reckon that is a snapshot of the moment the pump died...the very moment.
Pritty kewl.

 

[EastAustinSawdust]

Long overdue update here. Replaced the big Mallory fuel pump with a much cheaper and smaller one—an Edelbrock 17301—and everything has been fine ever since. This pump is really only capable of operating at the PSI/GPH range for my engine setup, whereas the Mallory was a much more powerful pump designed for racing setups. Granted, multiple times I checked the fuel pressure with the Mallory to make sure it was right at 6psi.

I also eventually dropped the tank, replaced the gas lines to the pump as well as the filler neck, and also replaced the sending unit which looked original. I will say that the tank itself was spotless inside, which was great to see. So I don't think I've had any problems with dirty fuel clogging my pump or filters.

If I had to guess, the Mallory pump was just too powerful for my needs and something about my setup was making it work too hard. Obviously that filter pictured above—albeit clean—was still constricting flow. I used to not have a filter in front of the pump, and previous pump (this is 2 pumps ago) still died. That's why I put the filter there in the first place. Either way, happy to have found a significantly cheaper and smaller setup that I've had no problems with.