Typical lift pump pressure

[hasselbach]

from my new gauges tonight, I see that my lift pump is in the low 20 psi range, is that correct? seems a bit high.

 

[Coolslice]

Mine stays between 6 and 8. 5 I myself am wondering how much effect cold weather has on FP and what is normal ? It seems I've lost about 2. 5 lbs since it has gotten cold here. I've seen all different ranges for FP on these 3rd gen. Mine is certainly on the lower end. I've not heard of one thats 20 though. Sounds a little high to me, but I'm no expert.

 

[JStieger]

The only time I heard of pressure >20 psi was when people added a pusher pump inline with their stock lift pump. With just my Holley I run ~13 psi at the CP3 inlet with no load.

Mine stays between 6 and 8. 5 I myself am wondering how much effect cold weather has on FP and what is normal ? It seems I've lost about 2. 5 lbs since it has gotten cold here. I've seen all different ranges for FP on these 3rd gen. Mine is certainly on the lower end. I've not heard of one thats 20 though. Sounds a little high to me, but I'm no expert.

I see the same pressure drop when cold. After about 15-30 minutes of the fuel circulating around and warming up, the pressure comes up. In the summer the first start pressure drop is about 1 psi less than fully warm; in the winter the first start pressure drop is about 2 psi less than fully warm.

 

[Vulcan]

That sounds way high for a stock system. You might want to verify that pressure reading and make sure your gauge/sender/isolator is working properly.

 

[KLockliear]

Yup, that's way high. Stock is typically 8-10psi at idle.

 

[hasselbach]

Yup, that's way high. Stock is typically 8-10psi at idle.

Okay, I am tapping into the line that goes from the lift pump (bottom banjo bolt near the drain lever-yellow handle) that runs to the front pump fitting (the one near the cascade valve). There is another line that runs back to the lift pump that t's into the pressure relief valve that I did not tap into.



My line is off the front pump using an adaptor from Genos. Now I am getting 15 psi, and when you shut the truck off, it stays there for sometime, (doesn't bleed off for a few hours). Is this correct?

 

[RJOL]

Your pressure reading is too high for the new "lift pump in the tank. " You have tapped into the right line, so I would think you have a gauge problem. Also, I believe you mean that you tapped into the line coming from the bottom of the filter, not the lift pump.



You don't say what type of gauge your using (i. e. direct pressure or electronic), but if it's electronic, check your wiring carefully. As an example, Westach used to tell you to make sure the sender, and the gauge were grounded to the same point. Don't know if that is your problem, but it never hurts to check the wiring...

 

[hasselbach]

Your pressure reading is too high for the new "lift pump in the tank. " You have tapped into the right line, so I would think you have a gauge problem. Also, I believe you mean that you tapped into the line coming from the bottom of the filter, not the lift pump.



You don't say what type of gauge your using (i. e. direct pressure or electronic), but if it's electronic, check your wiring carefully. As an example, Westach used to tell you to make sure the sender, and the gauge were grounded to the same point. Don't know if that is your problem, but it never hurts to check the wiring...

Mechanical gauge... odd. Gauge checks out good. Yes, I forgot that the lift pump is in the tank. I see over 15 psi and it stays there when the truck stops. If I drain the filter, it will go to zero...

 

[Big P]

I just did my gauges last week. I installed an Autometer 30lb electric fuel pressure gauge, and it reads about 9psi at idle. I tapped directly into the cp3.

 

[JCleary]

I have my Isspro EV with a Di Pricol isolator, ordered from Genos (like you, I assume)



I tapped my pressure from the same spot, and am seeing 7-8 psi at idle. Looks like you did it right to me. Perhaps you got the one super-lift-pump that slipped through q/c at the factory?



If I had to do it again, I think I would have left the coolant out of the hose from the isolator to the gauge. The vibration is wicked. I have to go under the dash and re-route the hoses and use a ton of zip-ties to keep the f/p hose from vibrating inside the split loom I used to run the hoses. I'm thinking the air may cushion the vibration.



The thing that surprises me is the time it takes for the pressure to drop. As soon as my l/p stops running, the needle drops to zero within 1 second or so.

 

[Cattletrkr]

JCleary,



Try moving the banjo that you have mounted on the CP3 to the bottom of the fuel filter cannister. Same line, other end. I had a nasty vibe too until I moved it. Perfect ever since.



Won't air in the line mess up your readings?

 

[JCleary]

JCleary,



Try moving the banjo that you have mounted on the CP3 to the bottom of the fuel filter cannister. Same line, other end. I had a nasty vibe too until I moved it. Perfect ever since.



Won't air in the line mess up your readings?

I may be plumbing my FASS direct to the pump, so I'm kind of stuck with the banjo bolt where it is if I only wanted to do it once. If I decide to go through the stock canister, I'll probably move it to the bottom of the canister as you suggest.



For the time being, I'm going to try to secure the hoses a little better to quell the vibe. It's only vibrating against the split loom, it shouldn't be that difficult. I'm thinking a few strategically placed zip-ties should do it.



According to the DiPricol isolator instructions, it's only necessary to fill the isolator with coolant providing the hose is shorter than 6 feet. I filled the isolator and the line with water, but when I cut the line to install on the gauge, some air got in. Once I started the truck, a few drips of water leaked fromt he isolator. There are some air bubbles in the line, but the gauge works perfectly. I think it would work just fine with no coolant in the line, just in the isolator.