Need help with diagnosing a severe power loss
 

A couple weeks ago I noticed that after the truck had been driven at least 8-10 miles at highway speeds, I was losing power and the engine seemed to misfire. It was most pronounced going up any sort of a grade. Cold starts have been normal and drives fine until then. I checked all the normal things to look at first, i.e. oil level, air filter, fuel filter, boost leaks. Everything looked good. Several times I drove less than 5-6 miles, and it showed no signs of any issues.

I finally happened to check the ICP and noticed that the connection had oil in it so I bought a new OEM sensor and installed it. Truck seemed to run fine and smoother so I thought I fixed the problem. Not so.

Today I brought my boys up to the pass to go skiing and the truck ran great until I started the climb up to the pass. Severe power loss, 1200F egt's, struggling to hit 40mph. A few times I pulled over to idle the egt's down to 400F, drive again, only to lose power shortly thereafter. There were periods where I noticed a few light puffs of blue smoke, but not much more than that.

Before I go to have any codes read, do any of you have any suggestions as to where else I should look first?

Is it possible fuel pump is dying on you? I see u have done the hutch and harpoon mod so screens are out but maybe fuel psi is down due to worn pump.

I'd try to get my hands on AE and do some testing. It will pay for itself pretty quickly if you have to pay almost $100 to get the codes read like I used to.

Can you post a link showing the AE every one is using?

You are absolutely right by that logic. I just might go ahead and make that investment.

That was one of my thoughts, but wouldn't that also reveal itself during cold running? Until the truck is fully warmed up, it runs fine.

I have a stretch of 12 hour days ahead and won't be getting to this until next week. Thanks for the input, and in the meantime I think I'll place an order with Clay on the AE.

Doesn't take much to keep the fuel bowl full when idling, warm or cold.

I also think it is a fuel supply/fuel pressure problem considering the problem is when fuel supply demand increases while going up a grade. Have you tried a WOT run on a more or less level road? 0-75 would be a good test.

AE is a good tool to have but will not help diagnose a fuel pressure problem. There is no fuel pressure sensor on the 7.3.

EDIT : You can use the AE to watch ICP and Duty Cycle. If you start loosing power going up a grade and giving it more throttle and the ICP and Duty Cycle keep rising and your speed doesn't increase that would point to a possible fueling problem.

X2 on the fuel pressure. Get a gauge and watch it while you drive, your inlet on the fuel pump could be full of crap. There is a little screen in there. If you have done the in tank mods and don't have a inline filter all of that stuff that was getting caught in the tank before is now going right to the pump. I see that your brewing your own bio diesel, I have to figure your filtering it some how before filling your truck.

AS far as it running fine when it is cold, I don't know if your like me, I don't get on my truck hard till it has warmed up. It only takes maybe 2 miles for my truck to get up to temp. Usually by the time I reach the freeway it is ready to rip.

bad batch of B100?

I should clarify my definition of a cold engine. I still consider the coolant reaching full operating temperature as a cold engine, (3-4 miles highway driving). When I believe the engine oil has reached full operating temperature, (3-4 more miles highway driving), that is what I consider a warmed up engine. I don't have 'real' gauges for coolant and oil, but this is just my own guess.

Just tried a WOT run at full coolant operating temp and it seems to have worsened. Almost as if it had a rev limiter. (Yesterday when we merged onto the freeway just after leaving the house, it ran fine with full power)

I'll look further into the fuel pump when I can. I think I was placing too much emphasis on oil temp related issues.

I have a clear inline filter before pump. One thing I did notice today, whereas before I hadn't, was the fuel pump seemed a lot noisier.

I usually do not get on it hard until I feel the engine oil is at full operating temperature.

And yes, I have a 4 stage final filtration system for my bio, with a 2 micron Cimtek hydroglass final cartridge. I run single stage reactions (.5 KOH titrations on average) and my fuel is always highly converted and well dried. I am now wondering if there are any incompatible components in the fuel pump.

With all of the conversion, moisture, and temperature testing I do on all of my batches, I am confident that it is not a bad batch. A batch of underconverted or wet bio wouldn't make it past the filtration on my fueling station anyhow. I would have also noticed something on my fuel filter or in the fuel bowl when I checked there. It was all spotless.

There is a rev limiter.

Noisier fuel pump could easily be a sign it's not working properly, as you have certainly already thought

You might find out if biodiesel has caused fuel pump problems by posting a question in the Alt Fuels Section.

Replace that inline pre pump filter, that could be your problem. When I used to run wvo with a pre pump filter the pump would scream when it did not have enough fuel in it. The rotory pumps (oem too) are ment to push, not pull fuel. So if that inline filter is even slightly clogged the pump will not be able to get enough fuel to the engine.

-Joe

I had this same exact problem and over a period of 3 months. Finally the fuel pump quit turning on. R2'd fuel pump and all GTG.