yea if the diaphram breaks .. alot of people keep dual pumps mechanical and electric .. can be done after the mechanical pump or in a parallel line feed not in series .. often people that suffer air intrusion problems do this so they can flip the switch and prime the pump and then turn it off .. or run it in the event the mechanical unit fails

about dumping diesel into the crankcase .. wooow buddy .. i did that one when my lift pump failed ..

though in general i do prefer mechanical pumps .. i have an old spare holley elec pump i was thinking of adding inline also just as a ohh crap backup ..

but when my fuel pump failed this is what happened .. the vacuum pump started making a strange sucking loud noise .. and my brake light kept coming on .. low vacuum .. i thought my vac pump was on it's way out .. i had no idea the fuel pump was gone .. it was still pumping fine .. but a pinhole had developed on the diaphram (30 year old stock pump .. so i will forgive it)

fuel was leaking out the side of the pump and out into the intake of the vacuum pump making strange sounds as it compressed it .. also it leaked fuel internally into the crankcase .. i noticed when i got a good look at the vac pump and saw that it was wet and smelled like diesel ..

i pulled the dipstick and the oil was waaaaayyy overfull probably like double the oil .. lol .. but it didn't do no harm .. diesel is oil after all .. if anything it really cleaned up my lifters .. CAT actually used to recommend if doing a deep oil change and clean out to empty oil and refill with straight diesel and run the motor an hour then drain and add fresh oil ..

STILL it's not cool to run waaaayyy overfull for like ever on any oil because oil pressure would be high i would guess ..

just wanted to share a funny story ..

when i changed out my lift pump the vacuum pump returned to proper quiet and effective operation

 

Thanks guys for all the input I think I'll temorarly bypass and evently get a new mechanical fuel pump

 

Thought I'd show you what it looks like

 

^^^^^ Wow, awesome sky. If the guy who painted this were alive today, and taking photos of trucks, he would take that pic.

 

Yea alotnof people make fun of Indiana but the sky here is quite beautiful it has great sunrises great sunsets and pretty blue