Modified 6.4 - Air in Fuel - 7 wks without truck - please help

[MT_Diesel]

Hi guys, I’m looking for ideas or suggestions of what to test and/or fittings to check to help the local dealership fix my truck since they can’t seem to figure it out and I’ve been without the truck for 7 weeks now. This seems to be a real head scratcher for RCD as well as the local dealer. I’m hoping someone has run into the same/similar problem and been able to fix it. I know there are a lot of 6.4 experts here on PSA. Thanks for any help you can provide!

The Problem:
Truck is getting air in the fuel somehow and randomly dies. When it runs it is running smoothly like there are no issues, then spontaneously dies (due to airlock in the fuel according to dealership). The dealership says it is only affecting the left bank – not sure how they know this, perhaps diagnostics – which is the same side I just replaced 2 injectors on. Dealership and RCD suspect air in the fuel likely caused the failure of the injectors in the first place. Truck won’t run long enough to get to operating temp.

Fuel System Mods (all done ~7k miles ago):
FASS 150 LPFP
Diesel Dr. Duel Fueler kit
2 new HPFPs with ~7k miles – one locked up shortly after duel kit was added and was replaced with a new one
Elite fuel bowl delete
Ported fuel rails
Six 60% injectors from orginal build ~7k miles
Two new 60% injectors – 18 miles
Stock fuel cooler

Background:
I purchased a 2008 F350 in March. The truck was built by River City Diesel and was local to them so I had them do a pre-buy inspection and they gave it a clean bill of health. I drove it almost 2k miles home and put another 500 miles on it over 3 weeks when I got home. Truck ran great. I only mention this because I believe all was working normal when I purchased it. From the little I know it wouldn’t have made it 2500 miles with an air in fuel problem. I did retune it from the custom (to this truck) RCD 485 to custom RCD 525 a week or two before the first problem. Anyway, I went out to start it one day and it idled really rough when it kicked into the high idle. No performance diesel shops local to me so I had it towed to the local dealer.

Diagnosis showed 1 hung injector and another possibly bad injector - both on the left bank (60% injectors with 7k miles total on them). Dealership pulled the 4 left bank injectors and sent them to RCD for testing. 2 of them were bad as the dealership suspected. RCD sent the 2 good injectors plus 2 new Alliant 60% injectors with new fuel lines for all. Dealership reinstalled the injectors and I got the truck back. I drove it a total of 18 miles before it died on the side of the interstate (just a short 3 mile in-town stretch). Truck would not start so back to the dealership. Truck had seemed to be running just fine though I do remember thinking the rail pressure at idle (in gear) was a little high and moving around a little more than usual. But I've only driven the truck for 3 weeks so I don't know it that well. Also of note, when the truck died (in a downpour no less) I noticed that the bolts holding the flange between the two turbos were missing and there was a visible gap between flanges. Dealership said that is not related to the work they did and that it needs a new gasket & bolts and of course the cab has to come off for that (according to them). Suck. Perhaps I’ll do that myself cab on if it’s not too difficult.

Dealership said air locked fuel system caused it to die. They said it is getting air in the fuel and appears to only be affecting the left bank. RCD recommended they drop the tank to perform a test on that – not sure whether a pressure test or other test. Dealership didn’t do that but hooked up a clear tube at/near the fuel cooler and cycled the LPFP to see if motor was getting aerated fuel. They said the fuel was not aerated – pure fuel. They said when it is aerated you can see bubbles and foam. The dealership techs are completely clueless when it comes to the modified components and are relying on RCD for tech support. RCD has been awesome continuing to help me/them out.

To me it seems like air would have to be getting in the suction part of the fuel system. I would think any leaks from the LPFP to the injectors would show up as fuel leaking out, not air getting in. Would there be any value in pressure testing the tank or visually inspecting the pickup in the tank? Or could air be getting in at the LPFP? Are there any other tests that can be done to check for aeration in the low pressure or high pressure portions of the system?

I’m going to call around to the nearest performance diesel shops – minimum 2 hrs away – to see about trailering it to one of them if the dealership can’t make any progress in the near future. But I wanted to solicit help from the PSA brain trust before I haul it out of town.

Thanks again for any help you can provide!

 

[sootie]

how are your dual fuelers set up, do you have one pump feeding one bank?

 

[MT_Diesel]

I'm not sure because I haven't had a chance to get familiar with the fuel line routing and the dealership can't figure it out. We are waiting on RCD to send a fuel system schematic. I'm not sure if the dual fuel kit includes all the lines or if RCD fabbed them. If one pump feeds each bank then it would make sense that there might be an issue with one pump.

 

[Breaking Habits]

This is a Diesel DR Dual Fueler, not purchased from us or installed here at the shop. We built the motor for this truck and the injectors, but everything was installed & installed by a garage about 40 minutes from the shop.

Its kind of a head scratcher on whats going on. Given my experience after just doing my truck, I suggested taking the fuel system apart, and re running all the lines to make sure the feed/return and everything is as it should be.

I ended up running everything new on my truck when we did it, using elites twin k16 kit, and Nathannial/Tadd's exact instructions, and the fuel system popped off instantly without a single issue

Thats my .02 on the situation.

 

[MT_Diesel]

Thanks for the clarification, Jared. I did not realize you guys didn't install the dual fueler. Hopefully you didn't take it that I was throwing RCD under the bus as it's just the opposite. You guys have gone above and beyond and have earned a customer for a long time. The dealership, on the other hand, seems to be a goat show.

I'm hoping to find a solution that isn't big $$$ or exhaust every other possibility before looking at going with elite's kit. Thanks for you're continued assistance with this, its greatly appreciated.

 

[NathannialD]

how hard would it be to eliminate the twin pump stuff just for diagnostic purposes? i have no idea as ive never seen that kit installed.

 

[Breaking Habits]

Thanks for the clarification, Jared. I did not realize you guys didn't install the dual fueler. Hopefully you didn't take it that I was throwing RCD under the bus as it's just the opposite. You guys have gone above and beyond and have earned a customer for a long time. The dealership, on the other hand, seems to be a goat show.

I'm hoping to find a solution that isn't big $$$ or exhaust every other possibility before looking at going with elite's kit. Thanks for you're continued assistance with this, its greatly appreciated.

No worries Ryan. I just have to clarify it since we only kind of cleaned up the little inconsitancies we saw from there.

I think in the long run, you're going to be money & heartache ahead doing that.

 

[suprdzlduty]

One thing to consider is that the Fass could be heating up, getting weak and dropping pressure, more importantly volume. The hpfp need volume over pressure...10lbs is what most lp systems are regulated at. Sounds like the dealer looked to see if it was getting air but I doubt the pump was hot when tested. Let's say the lp pump is good...now plumbing has to be the next part looked at. Isolating the pumps would be ideal, ie plumb it so one is feeding the injectors. Maybe you could post some pics of how the supply lines are run to the pumps to give us an idea what this kit looks like...if one pump feeds each bank, then one could be starving for fuel, which would cause aeration in that bank.

The bolts missing and gap between the turbos is normal, unless it is leaking exhaust then it would need a new gasket, but still wouldn't need bolts and still be a gap.

Back to the fuel tank...some of the early Fass pickup tubes caused 1/4 tank issues but I don't think they offered pickup tubes for the 6.4's but I could be wrong. I'm gonna assume you have plenty of fuel in it to eliminate an issue like this...

 

[78f100]

I have the dd dual fuels also, it's not real easy to isolate as the front pump feeds into the rear pump. I had a very similar problem with mine last year, after many hours of head scratching I found a broke injector cup. It was putting compression in my fuel system. I had changed injectors a few weeks before and used a new tq wrench that was not correctly calibrated. Basically it over torqued to injector pushing it into the cup hard enough it put a star Crack in the bottom. It ran fine for a few thousand miles then started acting up. It was obvious when I pulled the injector, carboned up and o rings burnt.

 

[webb06]

I have the dd dual fuels also, it's not real easy to isolate as the front pump feeds into the rear pump. I had a very similar problem with mine last year, after many hours of head scratching I found a broke injector cup. It was putting compression in my fuel system. I had changed injectors a few weeks before and used a new tq wrench that was not correctly calibrated. Basically it over torqued to injector pushing it into the cup hard enough it put a star Crack in the bottom. It ran fine for a few thousand miles then started acting up. It was obvious when I pulled the injector, carboned up and o rings burnt.

I was leaning towards a cracked cup too. Or a bad washer on the injector causing compression to get in the system.


Sent from my iPhone using Tapatalk

 

[suprdzlduty]

Cracked cup definitely makes more sense.

 

[sideactiondiesel]

With all this being said ... Has anyone taken the time to check and make sure the second k16 feed line feeding in the correct port ?? And return on the pump is returning ??

 

[Breaking Habits]

With all this being said ... Has anyone taken the time to check and make sure the second k16 feed line feeding in the correct port ?? And return on the pump is returning ??

Right there with you Brenton. Kind of my thought of pulling all the lines off and re running as if installing the kit new

 

[MT_Diesel]

Thanks for the ideas guys. I'll pass those along to the dealership. I'll also post up the fuel system layout when I receive it from RCD as that may clear up some of the confusion on the current routing.

Any idea of how I could test for the LPFP getting weak and not keeping up? Hook a pressure gauge to the low pressure system? I wouldn't think the LPFP would be heating up during the short durations the truck is able to run before it dies. But the pressure test won't test for volume. However, given fluid dynamics, if it wasn't supplying the volume demanded by the HPFPs then there should be a corresponding pressure drop in the low pressure fuel system.

Can anyone answer how one HPFP feeds the other on the Diesel Dr. system? I know the K16s can't tolerate much over 10 psi for supply pressure so they can't be running in series, can they? I would think they'd have to be running in parallel. Or does the fuel return from one pump provide the fuel supply to the other pump?

Jared & Brenton,
Would misrouted lines really be a concern if the truck ran great for so many miles? To my knowledge none of the high pressure fuel lines have been disconnected since I've owned it. I would think if things were hooked up incorrectly it would have never ran right. But I could be wrong.

I believe the previous owner had some fuel system issues when he first installed the dual fuelers, but my understanding is he got that sorted out and it ran fine after that. Jared, perhaps you know more about that I since you're familiar with the trucks history.

Thanks for all the suggestions and keep them coming.

 

[78f100]

It's not likely the lines are routed wrong, only 1 real way to plumb the dd kit. Basically the factory pump feeds bank 2 the front pump is plumbed to bank 1. Then the two open ports that normally would go to the other rail are plumbed together. There's no way to route them wrong without re bending the lines. If it's plumbed wrong on the high pressure side someone tried really hard to do it wrong. It is possible to have the inlet and the return flipped.

 

[NathannialD]

I know the K16s can't tolerate much over 10 psi for supply pressure

this is untrue and wont cause any issues you are having. we have run over 25psi to feed the k16 with no ill effects.

to answer you question yes you could run a pressure gauge so see what the lift pump is doing, if it cant keep up the pressure will drop to 0

 

[MT_Diesel]

Thanks for the correction, Nathaniel. I thought I had read several threads about seals in the hpfp starting to leak at much over 10 psi. But you guys would definitely know.

 

[sootie]

Thanks for the correction, Nathaniel. I thought I had read several threads about seals in the hpfp starting to leak at much over 10 psi. But you guys would definitely know.

you arent entirely wrong. i know of at least three that leaked over 12 psi

 

[Luke@MillerPerformance]

I would lean towards something not being hooked up right with the high pressure system after the dealer did the injectors. Dealers almost never work on anything that's not stock, big injectors, dual fuelers, etc are completely out of the box for them.

As suggested, I would have them remove the dual kit for now and hook up the single stock pump. If makes rail pressure and starts then you know something is off with the second pump.

Bolts missing out of the turbo is normal, they aren't there from the factory. I believe there are alignment dowels that thread into them to help keep the turbos together on install.

 

[NathannialD]

you arent entirely wrong. i know of at least three that leaked over 12 psi

funny thing about that, 90% sure we figured out recently. just a fluke deal, Tadd noticed an odd change on a reman pump we got. we will see if it can be proven as the cause. if so the fix is pretty simple.