Long post, sorry.

After replacing my second lift pump a year ago, I decided to install a Holley Red low pressure pump just in front of the fuel tank - to help things along. The numbers have been good - 21 psi idle, 17 cruising at 65 mph, 13 wot.

Yesterday I tried to start the truck and the Holley made a few stuttering noises and quit. Today I replaced the Holley with another, and decided to tear down the dead one to see if I could figure out what happened.

Fist thing I noticed was diesel fuel seepage on the casing. It was odd that a lot of seepage came from the top, where the wires exited the casing. When I opened it up, diesel fuel had partially eaten away the big magnets the coil spins in, and crudded everything - points, copper contacts, wiring, bushings and bearings, with a diesel/magnet "mix" of sludge.

The coil shaft also spins the rotor that pressurizes the fuel, and there's a bushing the shaft rides in that separates the coil/magnet/contacts/electronics compartment from the rotor/fuel chamber. That bushing had failed, and fuel was "climbing" the spinning shaft into the upper electronics. The tell-tale was the diesel seepage coming from the upper part of the pump.

I called a friend of mine who owns a Dodge CTD. He had replaced his stock LP configuration with a Holley Blue about six months ago. He checked his, and sure enough, he had seepage coming from the top of his Blue. When we tore it down this afternoon, the Blue had the same issue - a shaft bushing that was allowing diesel to climb into the electronics.

I know the Holley Blacks had problems with burrs on the rotors or shafts a while back. Not sure what might be causing this, or if it's just coincidental. A tech here suggested that pressure spikes were created between the IP, stock LP, and the Holley, and might be pounding the shaft back and forth in the bushing and wearing it prematurely.

In any event, something to look for if you're using a Holley - diesel seepage on the outside of the pump.

 

I wonder if you would run into the same problem if you replace the stock lp and use the Holley in its place. That is what me and BigBlue have done. Is it possible to get that pressure "spike" with this setup? So far, I haven't noticed any of this "seepage" on the outside of the casing. When I get a chance, I will take off the pump and do a break down of whats going on inside.

 

hey, sorry to hijack the thread, (delete it if you dont like it) but i saw the cxt in ur sig.... could you post a pic of that please?? i kinda want one but the price tag is kinda in my way

 

Hmm. That's interesting. I'll have to check mine out. Thanks for the heads up. BTW, how are you liking the CXT.

 

I have a Blue and am running it with out the stock LP. I'll check for top leakin also, but I just installed it about 500 miles ago so nothing may show just yet.

 

Well I checked mine and I found no leaking from the top, but the 4 bolts on the bottom of the pump had diesel on them. I guess its leakin around the bolts some what.

 

My LP is headed south,.....and I've been researching this issue pretty hard. I learned that these Holly pumps are NOT rated for diesel fuel. My local autoparts dealer even said he nor Holly would not stand behind any type of warranty if the pump was used in a diesel application?

I ordered the carter, w/ vulcan kit.

Sounds like the way to go on this LP issue w/ sec gen trucks is the in-tank conversion. (I'm going to try the carter / big line kit,......when that goes, I'll probably do the in-tank conversion).

 

Gear Poet,

You mention a tech thought it was pressure spikes from the IP that caused the failure. Surely the fuel filter would snub any significant spikes before they got all the way back to that lift pump. Just a thought.

 

Pressure spikes and filter snubbing was the subject of debate in these forums a while ago. If I'm remembering correctly, several people took measurements and claimed that no, the filter did not snub such spikes significantly. Which is why, when the stock LP dies, it's usually because the check ball assembly has failed.

In any event, the filter sits between the IP and the stock LP, and would not be a factor in the line between the tank LP and the stock LP. But I agree, so far it's only speculation.

Out of curiousity, what does it take to rate an electric fuel pump for diesel? I've been told it's usually that manufacturers do not run tests on any fuel except an intended one, and therefore will not certify for any fuel except the ones tested.