LorenS

I didn't take my 500 mile trip today, but did do maybe 300, 100 with a small Kubota on my 16' trailer. Got around 15 MPG, so not bad, not great. I need my long trip that I've taken numerous times!

I'm sure of no external leaks. If a crossover tube is leaking, it can't imagine it's much because the engine runs very smoothly. I don't have boost or EGT gauges, can say exhaust is clean.

Yep, up to temp.

Yes, stock injectors.

I agree the ones I took out were junk, but it's hard to not be aggravated when I got better mileage before the switch. I may reset the valves this weekend to something looser and see if that helps. I went a loose .008/.018, tight .009/.019. I tried to be as consistent as absolutely possible. Once set I checked them all again before reinstalling valve cover. For a stock truck, does DAP have a recommended injector? Reliability and fuel economy are my main concerns. Whatever HP (235 factory rating) I have now suits me fine - of course I wouldn't say no to a little more if the penalty was small! Don't you guys set your Quad things to advance the injection to make more power? Isn't that what weaker injectors do, just with a less than optimal fuel atomization? My console used to tell me I was getting 18.5 MPG or so, and I was at 17.5ish. Now it says 13.8 MPG, and I believe it. Putting the truck in neutral on a very small slope, the truck rolls as expected. In gear (auto trans) and off throttle, the truck behaves as always, so I don't think I have brakes dragging, etc. Lift pump pressure same as always. I have no noticeable black smoke, same as before. Is there a cam/crank position sensor that I may have bumped while working on the truck, and messed up timing? I may put 500-600 highway miles on it tomorrow, will certainly know my MPG more accurately after that trip.

My assumption is that they were the original injectors, so 280,000 miles. I wasn't having any obvious problems, just changed them as a maintenance item.

Finally tested the old injectors, they varied from 3,000 to 3,600 PSI pop pressure, one did not sound like the others. On most, only 3-4 holes of the seven sprayed fuel. Of course, I change the injectors and set valves, and wind up losing over one MPG, hand calculated. Overhead gizmo says this tank will be even worse. Same weather, same commute, driving the same way. No fuel leaks, engine "smooth" for an ISB - a sewing machine it is not.

Woo hoo! I hought that's what the fitting at the rear is for. She ran smooth as butter on the 30 mile drive home last night, so I'll assume none are leaking and down on pressure.

...Wish I'd remembered this yesterday. Do leaks wind up in the oil, thus destroying my engine? I'll check oil level every 30 miles or so for the next few days, is that sufficient?

An hour?! I think it took 10 minutes to get the valve cover off, fighting the heater hose, worried I'd tear the hose. I also took all the lines off, clear to the VP44. I had your directions printed off, I thought that's what I was supposed to do... I hope I never have to do that again, but I know next time would go WAY faster.

What's the normal time to change injectors for those of you who do it all the time? Yesterday I changed injectors, set valve lash, and installed a Vulcan banjo bolt eliminator kit from filter to block mounted pump. Took about nine hours, though had Dirty Jobs and Strange Inheritance on in the background to distract me a few times.

I fall into the more MPG camp. With MBRP 3" exhaust, HY35, DDRP lift pump (on a relay, and yes I know you folks hate them), 3/8" hose to the filter, 1/2" hose to the VP44, I have a set of stock rebuild injectors that are set to go in this Saturday, along with setting the valve lash. I bough the adapter to test pop-off pressure of both the new ones and the old ones. What can a guy do next to safely aid MPG? I already drive slowly and have no substantial brake drag, etc. Mid 17s to upper 18s is my norm. I also have an Edge EZ that my dad used on his NV5600 dually, but I have no idea if it can be used on an auto. I am willing to purchase a Quadzilla and injectors or nozzles that are EDM'd/honed, etc., if that will help me get better MPG. Even buy a HX35 or similar. The most I see me ever towing is 12k pounds, and with an auto transmission believe me I will baby the thing. I looked for an article in the 24V section outlining a logical build sheet for guys starting out, but didn't find anything. Time spent on DAP's website didn't yield much, either. All the hole number and size ratings in the world don't do me any good if I have no idea what stock is!

I found this earlier while looking for real Cummins (not molested by Dodge) VP44, 6-cylinder trucks mated to Allison 5/6-speeds. Thought I'd share. Not sure if it's what I consider an ISB, or if it's the common-rail variety. https://quickdrawbrand.com/product/cummins-isb-3-9-frame-cut-with-allison-1000-5-speed-overdrive-transmission-prewired/

That's what Guinness Stout is for.

Boy howdy, if that was oak and hickory imagine how many briskets and slabs a guy could smoke...