Stock fuel pump and 175/75% injectors.

[DZL JIM]

Injectors are 175/75% that I fed with a Bosch 044 pump with 5/8" draw straw, and regulated return. I can't recall where I got the return deal 5 years ago, from a guy that got banned from this site for whatever reason, uses hard lines to Aeromotive regulator, then returns back to tank. Factory top filter/supply housing still there and used, had pre-filter and pump on frame rail.
The first 044 pump lasted 4 years and over 30k miles. It went out last spring. Replaced it with another 044 pump, which lasted about 1000 miles. I am not after high HP with this truck any more, and just want a nice reliable daily driver, so I put the stock fuel pump back on, with stock lines. I didn't change anything with the regulated return set-up, just swapped the stock pump back in place.

Before with the 044 I could hold 65 psi no matter how hard I was on the throttle, it would only drop a couple psi at wide open throttle.
Now, with the regulator set at 68 psi, it drops 10 psi just trying to maintain speed at 55 mph. As I push the throttle down, the fuel psi drops accordingly. If I hammer it, pressure will drop to 20 psi.
I changed the fuel pump thinking maybe that pump (originally off the truck with 70k miles) was bad. No change in pressure.

I know big injectors need fuel, but I would expect with a light foot to maintain speed, there would be no issue holding psi. I can literally move the fuel psi gauge with the throttle pedal, without accelerating or blowing smoke. This has me stumped.
Any advice here is greatly appreciated.

 

[Mdub707]

The pump just can't keep up. I notice what you see on stock injectors with hot tunes. I used to measure fuel pressure at the back of the heads too and it would drop hard. This isn't uncommon. You need more pump. I'd either stick a factory 6.4 pump behind that 6.0 pump, or take it all off and get a factory 6.7 pump.

Or just upgrade to a fuelab or aeromotive.

 

[DZL JIM]

Forgot to mention that at idle it drops 10 psi when you stab the throttle.
Also, I have had 2 other trucks with big injectors (both 190/100%), the same regulated return set-up, and the stock fuel pump had no issue except on a hard throttle run. This truck is way worse than those other 2 trucks.

Do the 6.7 pumps hook right up, as far as supply and return connections?

I have had mixed results with aftermarket stuff for daily driving and reliability and I really want to go back to stock something. I will try a lower hp tune and see if that helps. If so I'll just tune back for now till I figure something out.

 

[BufertSS]

I am currently having about the same issue. I put a AD150 on recently and that has made it driveable. (I.E I can get up to 80 mph without going wot and hold pressure just fine.) If I do go WOT it will drop just as yours. I am currently trying to figure out if its the lack of pump or restriction through the fuel bowl.

 

[IIVonnyII]

I would think it is just a lack of fuel delivery. despite having bigger injectors on a different truck with the same setup.. each truck has its own quirks and personality. I ran my 205/100s on a stock pump and it would drop from 55 - 10psi . I thankfully only did that once or twice. I went to a twin superduty pump setup which worked awesome, dropped 10 ish psi at wot in a race file, street files it was fine. Now I run an A1000 . been on there 5kmiles no hiccups whatsoever. only drops 2 psi at wot.

 

[DZL JIM]

With the twin SD pumps, how did you plumb them?
Use check valves?
Did you change line size at all?

 

[IIVonnyII]

With the twin SD pumps, how did you plumb them?
Use check valves?
Did you change line size at all?

I built a mounting plate out of 3/8'' around 16'x10' in that ballpark.
mounted the pumps in series, bumped all the lines up to a -8 feeding the bowl and return to tank. had a spin on filter head and ballvalve on either sides of the pumps . mounted it along side the frame rail. with this fuel system even with it dropping a bit under WOT , ran a 12.58 @ 106.5 in my crew cab full weight. definitely moves some fuel , and its reliable as ever

 

[BS Hauler]

In series means you had one pump supplying the other pump. Or did you mean in parallel where each pump pulled from the tank and pushed together towards the filter.

 

[shmoozer]

I'm a really big fan of the 6.7 pump. It has zero problems keeping up with my 205's, and maintains stock reliability.


Sent from my iPhone using Tapatalk

 

[cRaZy8]

FWIW my stock 6.0L pump backed up by a 6.4L pump is rock solid on all tunes with 175/30s.

I gutted the filters on both pumps and built custom 'check valves' for both.
I have twin Racor filters feeding this setup from a sump.

Home built RR with Aeromotive FPR set to 58psi.
Never budges.

I keep a 6.0 & 6.4 pump cartridge in my tool box as spares.

 

[Merc82]

I'm pretty happy with my 6.7 pump and CAT filter setup I built for my truck. Pressure doesn't budge with my 190/30s. It feeds a Fuelab regulator set at 60 psi through a "y" fitting in the back of the heads. Return line goes back through the pump and into a bulkhead that I installed in the top of the fuel tank.

 

[Mdub707]

In series means you had one pump supplying the other pump. Or did you mean in parallel where each pump pulled from the tank and pushed together towards the filter.

Series. The 6.4 pump is a lift pump and only pushes 10-15psi or something like that, so think of it as a lift pump for the stock 6.0 pump.

If you're doing a 6.7 pump then just run it as a standalone, it already supplies 55ish PSI as needed.

 

[BS Hauler]

Thanks for the clarification 707

 

[SICKS LITER]

It took 2 stock pumps to maintain pressure when I had 155s. One wont cut it