Is there anyway to eliminate that lift pump with primer for an electric pump, something like the 24V engines have? So you can just crack the bleeder and turn the key to "on" and let it prime?

 

I've never seen a P7100 injection pump fed by an electric pump, so I don't know how well it would work. I sure don't like the idea of replacing the most durable dependable part of the 12 valve with the poorest, weakest part of a 24 valve.

 

I never use the primer pump button to fill and bleed fuel filters on a 12 valve.
Just pressurize the fuel tank to no more than 10 psi with the bleed screw open. Takes less than 30 seconds to fill an empty filter.
I do this enough that I have a tank cap with an air chuck tapped into the top but you can also use a blow gun wrapped in a rag.
This also works excellent for finding fuel system leaks.

 

i tried the electric pump out of a gas truck on my 95. it did not keep up with the 12 valve. a buddy of mine tried a holly electric pump even without the pressure regulator it just barley kept up killed fuel mileage. we both are back to stock lift pump.

 

Where did you drill the hole in the cap?

thanks
John

 

Right in the middle of the top. Got the stock cap from a buddy who replaced it with a locking type.

 

most durable? i'm not 100% sure, but i'm pretty sure that my lift pump that i just replaced (less than 10k ago) after my last one failed is now failing. i've got a high pitch tapping noise and low power. am i just unlucky?

 

You're unlucky.
I've worked on hundreds of 12 valves, some with over 500k and have never replaced one lift pump.
Perhaps I'm just lucky.

 

hey infidel, do you think running high %'s of biodiesel could be causing problems with the lp?

 

No, in fact it should make it last longer because of increased lubricity.

 

I used to have this problem about every 6 months when I lived in HOT Texas and about every 2 years now that I live in cooler PA. The return line from the injection pump since it runs on top of the engine gets too hot and will develop pin holes which will break the vacuum on intake side of the injection pump. To start the truck you have to prime the lift pump if the truck sits for a 2 or more days.

Easy test to see if this is the problem....Park your truck on a hill (doesn't need to be steep maybe 1 foot grade over the length of the truck) with the engine on the down hill side. If your truck starts after a few days without having to prime it, then splice in a section of return line from the injection pump down past the engine to about the firewall.

Now I've heard alot of stuff about the marine grade hose working best. But it is expensive and there aren't a lot of boat supply places in western PA. So the last time I fixed this on my truck, I put the regular fuel inside a section of heater hose. The heater hose seems to keep the direct heat off of the return line and I haven't had a hard start in a few years.

 

Will return lines results in a SIGNIFICANT decrease in fuel economy ???

 

In the case of my 3500 it sure did, I lost a full tank on the ground in less than 30 miles when the hose split in half. Normally unless you you are loosing a significant amount of fuel on the ground a return line leak won't effect mileage. In fact a air leak in the return line won't effect the way the engine runs at all, it will just be hard to start.