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Toxic Masculinity
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3,623 Posts
Discussion Starter #661
OEM fuel pump hitting a lean spike (13.87 afr) at 6,500 RPMs and with 50 lb/hr injectors it must be the 12 year old stock fuel pump.

Replaced with a drop in Walbro 255lph to avoid low fuel pick up issues when modding the stock bucket. I've read less than 1/2 to a 1/4 tank sometimes there are pickup issues under hard acceleration.

Like everything on this build I wanted to do this myself without asking for assistance so I used the tilt bed method.

At 62 years old I didn't even attempt lifting the bed by hand and trying to shove in a prop board. Using a 20 ton bottle jack along with my floor jack I carefully lifted the bed to get to the pump. Then used a jack stand for added safety.





Old Pump



New Pump







Installed

 

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Big Louie
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3,012 Posts
I bought a spreader bar off amazon that picks the bed up from the rails using a cherry picker, just something to consider if you think you'll have to do it again
 

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Registered
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1,678 Posts
you can come do mine now please :happy107:
 

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Toxic Masculinity
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3,623 Posts
Discussion Starter #664
Well...

I've always had to turn the key to the run position > off > on > crank > to start the engine. After the initial fuel prime my fuel pressure gauge on the rail drops quickly to zero losing the prime.

I replaced the fuel pressure regulator (Delco), fuel filter and the fuel pump. I was hoping it was the fuel pump check ball causing the pressure to bleed back to the tank but It still lost pressure.

Logically the only other thing would be the injectors. Replaced those today and you guessed it... still bleeding down. The truck runs strong and idles great, no black smoke or fuel leaks.

Only thing I can come up with is the new Walbro pump has a faulty check ball or no check system at all. It's irritating replacing everything and still have the same issue. One real good thing though, my goodness those old injectors were really loud, so loud it sounded like valvetrain noise! Now she's running so quite and smooth!

Since I thought I had a leaking injector(s) I felt it would be good to change the oil in case of fuel contamination. Last change was 1,020 miles. (note to self mileage 139,534) The inside of this motor still has to be squeaky clean :D

I'm going to rig up some quick connects to block the supply and return fuel lines so I can isolate the bleed back. If it's the pump check ball I'm going to install a one way inline check valve.



 

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Super Moderator
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6,278 Posts
thats a lot of blue smoke, yo
 

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n. fil-dert.
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6,857 Posts
I was wondering if it was tire smoke, did seem like a lot for how long they broke loose.
 

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Toxic Masculinity
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3,623 Posts
Discussion Starter #670
Installed the new Cam Motion camshaft today. Was quite surprised it idled great on the old tune. I've read it's a pain in the ass to get a good idle with a lot of overlap. The old "Sloppy Stage II" was 5 degrees, the overlap on the "Little Chopper" is 11 degrees. Cam specs 222/232 .595/.587 108+3

It's raining today so no test runs. Tomorrow I'll do some data logging and some MAF airflow tuning, timing, then tackle the VE tables next week... then some wot pulls! The valvetrain noise I had with the Sloppy Is no more!



Camshaft, parts & special tools to get the job done.



Front cover and balancer removed.



Sloppy Stage II cam ready to come out. 5/16 dowels holding the LS7 lifters.



Chopper oiled up ready next to the old Sloppy.



Install



Second Start (warm) Idle clip

 

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Toxic Masculinity
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3,623 Posts
Discussion Starter #672
What was wrong with the old cam?
The Sloppy Stage II is a good budget cam for the right application. In a heavy vehicle It lacks bottom end torque but really screams mid and upper. The lobes are kinda aggressive and noisy. I was getting weary of twisting the RPM's to 6,500, with the noise, worrying about breaking a spring and dropping a valve.

I upgraded to bushed trunnions along with hardened pushrods in hopes of quieting the valvetrain noise, only slightly helping. Cam Motion designs some really quiet lobes, during the initial start up, I can tell the noise is at a minimum!

The new cam should move the powerband lower, giving more bottom end, so I don't have to twist up a lot of RPM to feel the power. Torque is whats needed to get these heavy trucks rolling. I started out with a budget build that's why the ($245) SS2 cam was chosen. At the time I hadn't planned on stall converters, gears, built transmission etc. We all know how projects snowball out of budget and control lol.
 

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Registered
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2,792 Posts
It sounds really good!


Sent from my SM-G930W8 using Tapatalk
 

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x3 shitbox owner
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3,619 Posts
Perfect amount of chop


Sent from my iPhone using Tapatalk
 

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Toxic Masculinity
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3,623 Posts
Discussion Starter #679
Red did you get the problem solved with your fuel bleeding off pressure?
No just learned to live with it. Around 95% of the time cold it fires right up first time and around 75% hot. If it doesn't fire right up first try It always does on the second. She'll rev to 6,500 reading a 12.4 AFR so the pump and injectors are doing their job with no lean spikes.
 
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