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Old 06-07-2018, 09:15 AM   #1
zachu812
 
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Name: zachu812
Title: Too Much Time
Status: Not Here
Join Date: Apr 2016
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Posts: 419
13mm pump mysteries

I've been chasing an issue with the setup below for a couple months and I'm just about stumped.

When I first installed the pump I set timing to 20* using spill port and a stock pump gear. Truck had a noticeable lope at idle, ran great otherwise. I could blow the tires off from a 60 roll without brake boosting and the smoke would clear up to a dark haze at wot.

One day I was driving and mid pull around 3600 rpms in 3rd the truck started puking black smoke, barked the turbo, and fell on its face. I slowed down and the truck was running fine but I noticed the lope was gone. Went to do another pull and it left the line hard but fell off up top and wouldn't clean up the smoke anymore.

I assumed timing slipped given the symptoms and a stock pump gear, bought and installed a keyed adjustable gear and set timing back to 20* still ran the same. Checked all intake plumbing, compression, cam, crank gear, pushrods, and valve lash. Everything checked out fine. 215 pump went back on and the truck ran great, beat the **** out of it for a month with no issues at all. Checked over everything I could on the 13mm pump and talked to a few pump guys, couldn't pinpoint anything.

Pump went back on last night, this time at 24* and it acts the exact same. Lope is still gone and the smoke doesn't clear up at WOT, fuel pressure drops from 70psi to 50psi at WOT. It used to run great then started acting up and I cant find what could've changed to cause this. Should I open up the pump or is there something else I should look at? Any insight would be appreciated, I'm at a loss here.


13mm pump, 903 cam, 255 DV holders, 035 DVs, 5k gov springs,
AFC and plate all the way back, stiff afc spring
stock body 6x.013 injectors with another .020 needle lift
stock sized crossover tubes with edge filters removed
.084 injector lines
Fuelab 42401 lift pump at 70psi with -10 line into -8 dual feed
S472/83/1.0 cast SX-3
studs, springs, pushrods
Engine and head are otherwise stock
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1995 RCLB 4x4: H-pump, 5x.012s, HX35
2001 RCLB 4x4: H-pump, 6x.013s, S472/S488
EdzGarage, Matt's Diesel Supply, HTS Transmissions
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