Good list, I'll throw Torque Converter Slip in there for good measure.

I had this before I revisited my Hutch mod - I found a leak that allowed air into the fuel.

 

 

Mine was at the hose where it met the nipple on the tank. Do you by chance have a pre-fuel pump strainer (like the Racor) with a clear housing on the frame? Do you have some other pre-filter with tighter restriction?

Losing fuel pressure on stock sticks sounds odd. I have 160/100s that demand significantly more fuel than yours, yet my stock Bosch pump gets it done. I have regulated my pressure down to about 58 PSI.

 

 

That could be the problem with fuel pressure. The Racor PS-120 filters down to 200-260 microns which is more than sufficient to protect the pump. 100 microns could be overly restrictive with no added benefit besides keeping the actual fuel bowl fuel filter cleaner by stopping the larger particles at the pre-filter at the expense of flow/pressure post pre-filter.

 

I don't think that would be the issue as I have run a 100 micron pre-pump filter for years now and haven't seen any issues. There is no reason to but I know of several people that run 60-80 micron in that location without an issue. I would suggest the OP check the FPR oring and seat and make sure it is installed correctly. The only other thing could be if there was a lot of junk in the tank and the filter needs to be changed out/ Cleaned.

 

Correct on all counts with the initial cleanliness of the diesel fuel being a HUGE factor and is the most important part of the equation. If the fuel isn't filtered at the pump, some places don't filter at all, or filter properly, then the proper order of step downs by microns in filtration becomes of paramount importance which includes ease of maintenance at those specific filtration points.

I initially had the same Riffraff filter pre-pump with the H&H mod and had all kinds of issues due the crappy filtration that some of the local and distant stations had or didn't have. It was a real crap shoot and I got weary of the side of the road diesel splashing adventures. I removed it and replaced it with the Racor and haven't had an issue since besides getting to see the sand and straw etc visibly in the Racor which I couldn't see in the Riffraff filter and which gives me the ability to clean it ahead of the time it would begin to cause a problem.

 

I agree, the Riffraff inline fuel filter is a pain to change the filter, and you can't see in it. What Racor and filter micron level did you go with? Any link to Amazon with a parts list would be appreciated

 

Parts list that I used in the link below. Prices are subject to change...

https://www.ford-trucks.com/forums/1...l#post15275850

 

 

Looking at the log, it looks like a tune in there - or it could be another issue (like low fuel pressure). I don't trust the ICP sensor - I think it should be tested. I'm not saying replace it, but it looks just a little hinky at idle.

I don't know what your speeds were, but your torque converter is averse to locking up. Watch that PID when you get above in-town speeds. If the TC Slip doesn't lock on near zero while cruising down the highway - there goes all of your fuel economy.

Any way to do a good hard WOT up a steep grade, or tow something heavy?

 

That is an interesting observation you made about the TC. I am on my second rebuilt transmission, and after I got it back, I was wondering if anything in the transmission would be the culprit of poor fuel economy. In fact, now that I think about it, when getting up to cruising speed on the highway, it doesn't seem to hit top RPM and than settle down, it seems to want to stay pegged above 2,700 (going off of memory), until I back off with my foot, and than it will settle down. The attached data log does have several WOT, but nothing going up hill. I will be getting my tractor back on Saturday, so I can do a WOT with towing than. What causes the TC not to lock up? Bad TC?

Thanks for taking a look!

Apprecaite it,

Kevin

 

I can't say what the root cause of the problem is - it could be the TC, a valve, the fluid, a solenoid... I know squat about automatic transmissions. Mine locks right in at about 35 MPH in 3rd gear when I go easy on the throttle - but I have a Cody tune on an HD4R100.

 

I'll run some more seat of the pants test and keep an eye on the live data looking at TC slip. I read right past your comment about your comment it looks like there might be a tune on it. Should I go to a Ford dealer and have it flashed to stock just to eliminate that variable? I can't say that the PO of the truck didn't burn anything to the ECU, and it's been hiding on it. As far as the low fuel pressure, it only dips when hitting WOT from complete stop. I am planning on doing the Racor, and possibly dropping the fuel tank and checking the o-rings in the fuel tank quick connect hose.