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Another K30 with a 4bd1t... eventually.

15K views 144 replies 20 participants last post by  joshuak 
#1 ·
Greetings folks,

Newbie here, both to the forum and to motors swaps. I wanted to start a thread to share a project I'm working on and hopefully get some pointers.

So, this:

129063

In this:

129064
 
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#121 · (Edited)
Does some one have Isuzu spec for mechanical fuel pump pressure?

I’ve drawn a blank searching in the manuals I have and googlefu is weak.

Had a chance to go for a drive, fuel pressure was in 15-17 psi at idle and going down the road the first minute or so. Then fuel pressure dropped to 7 or so and endup at 0. Truck didn’t shut off though, ran poorly but ran.

Back in the driveway idling, it will surge between 0 and 7 psi it seems.



Decided to start at the back and pull it apart.

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Over here Russ asked about the in tank sock filter and I answered that I’d changed it 5 yrs ago with a new sending unit and tank. 5 yrs of little to no use is rough on this stuff, lol.

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Next is cleaning out tank and replacing sending unit, I’ll skip the filter sock this time. Let the others do their thing.
 
#122 ·
Does some one have Isuzu spec for mechanical fuel pump pressure?

I’ve drawn a blank searching in the manuals I have and googlefu is weak.

Had a chance to go for a drive, fuel pressure was in 15-17 psi at idle and going down the road the first minute or so. Then fuel pressure dropped to 7 or so and endup at 0. Truck didn’t shut off though, ran poorly but ran.

Back in the driveway idling, it will surge between 0 and 7 psi it seems.



Decided to start at the back and pull it apart.

View attachment 135911

Over here Rus asked about the in tank sock filter and I answered that I’d changed it 5 yrs ago with a new sending unit and tank. 5 yrs of little to no use is rough on this stuff, lol.

View attachment 135912


View attachment 135913

Next is cleaning out tank and replacing sending unit, I’ll skip the filter sock this time. Let the others do their thing.
That filter sock is plugged up - The fuel is not draining out.
 
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#124 ·
Pulled into the parking lot at work this morning and saw dripping from the front axle, popped the hood and realized fuel was squirting around on the passenger side. Shut the truck down and layed down some absorbent pads.

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Found a broken fuel return line right at the banjo bolt on the IP.

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This got me home.

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And I added one of these, eventually I’ll replace it with a more inconspicuous one. But for now it gave me peace of mind lol.

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#127 ·
To prevent that from happening again, find a shop that can fabricate braided lines w/banjo ends, they flex, hard line don't and when over torked they crack...yes, its a well known issue.
 
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#126 · (Edited)
There was no indication of either of those. Nothing whipped around there or is loose.

It looked to me like the brazing failed/snapped at the connection with the banjo bolt because it was flush. Edit! Tube after, because braze/weld is intact.

Full disclosure: this evening I added two of the three fasteners that hold the fuel filter mount because they were missing. It was held in place loosely by the nut on the green stud. In hindsight, if the return line connection was providing structural support to the filter and housing, vibration could have contributed to failure (?).

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#129 ·
 
#131 ·
Fuel pressure sensor continues to pay dividends, today it alerted me to another obstruction. Screen at banjo bolt feeding the mechanical pump this time.

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Cleaned and reassembled, then put a new fuel filter on too, cheap insurance I guess.

In a few weeks I’d to add a Racor 460-30 or similar between the tank and mechanical pump.
 
#132 · (Edited)
Data on air intake snorkel measured by vacuum, in of h20, Pre filter / Post filter

with Donaldson topspin 18/18.
snorkel only 10/13.
No snorkel Less than 10/10.

I put the snorkel on hoping to get fresh air to the engine, but the juice doesn’t seem worth the squeeze.

And with no snorkel (it seemed to me) there was less boost lag, allowing it to catch the egts before they got out of control (above 1200).

Thinking about a simple intake box under the hood like most pickup trucks have nowadays.
 
#135 · (Edited)
Did one of of my favorite modifications to the truck this weekend, added about 100 miles to the odometer! :)

So far so good, continue to monitor fuel pressure. Haven’t found anything published by Isuzu, but I did find a couple posts here on the forum.

One from bush67 (with tech) and a another from Benjaminearl (with his experience).
What I’m seeing is similar to benjaminearl’s numbers minus the 30psi of boost.

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#138 ·
At some point last week I read a thread in which you mentioned 15”, but this morning when I was trying to compose my post and give credit to my sources I could not find that post and found this other one. I will edit the original post because that means the snorkel is providing more of restriction than Holset allows for.

Thanks for the intel and the correction!
 
#142 ·
That may be my next course of action, lol.

Hopefully I’m getting all the fu*k ups out of my system and the next swap goes smoother. Sure is nice when it goes well.

I did momentarily feel like putting down my tools and walking away. It’s all good, just need to figure out what’s wrong and make it right.
 
#144 ·
Aside this setback, when you finish, you will have a unique and reliable rig.
 
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#145 · (Edited)
Replaced main shaft.



Put it back together, bolted the new 5th gear housing on and reinstalled the tranny.

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Heeding advice I added a brace from the transfer case to the bellhousing.

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And she’s out and about again.

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When comparing the solid rubber isolators with the liquid filled, there’s more vibrations during start up and shut down. But honestly fork those things… lol. My bad for using them.
 
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