Fuel Economy Drop

My father in law just got quite a boost in his gas milage by having someone tweak is fuel presssure. Not sure what was causing it to be off but it seems to have helped him. He's getting 20MPG going from Denver to Buena Vista (all mountain roads)

AlexG21 said:

My father in law just got quite a boost in his gas milage by having someone tweak is fuel presssure. Not sure what was causing it to be off but it seems to have helped him. He's getting 20MPG going from Denver to Buena Vista (all mountain roads)

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that shouldn't be an issue on a 7.3.. the HEUI IS the "high pressure" fuel pump.. it slams a shuttle valve down on the fuel chamber when energized.. if the pressure was low enough to affect driveability, he gave it a cold pill.. masking the symptoms without "curing" the problem.. although shimming FPR's to 70-ish lbs fuel pressure is a common mod..

get rid of that POS K&N filter!

1. check your brakes. all 4 of them. make sure a caliper is not dragging.

2. look for oil wet stain around all the charge air pipes and the interecooler. if there is wetness, you need to pull them apart, clean them and put them back together. making up a test port can be handy. but do NOT charge it with more than 5 psi air pressure.

3. might be worth changing the MAP sensor, on the D/S of the firewall, look at the hose routing from the turbo towards that side and you will find it. little black box.

4. if the 16yo has been driving it, has be been messing with stuff under the hood like blow off linkage to build more boost?

Well, time is short, so I've been fiddling with it a bit at a time. I did replace the fuel filter. The paper on the old one was a very dark brown. That definitely helped.

But now a new problem, or a worsening of the old one. We went camping over Thanksgiving week towing our trailer about 200 miles. A little weak on power still, but about 1/3 of the way home we stopped for lunch and it would not restart. Cranked, cranked, cranked...no start. I had been running it kind of hard, but the factory temperature gauges were still "normal," and probably more accurately the tranny hump wasn't too hot and there were no hot smells under the hood. After being stopped for about a half an hour, and fiddling with it for about 15 minutes, it suddenly started just fine. Last week, it did the same thing to my son when he was just running around town. Barely warmed up, stopped for about 20 minutes, not start, no start, not start... He called me, tried it again, and it fired up fine.

After digging around here, I've found that the ICP sensor connector has a film of oil on it. I unplugged it and took it for a test drive, and it worked fine. But after stopping at the grocery store, the check engine light stayed on. Plugged it back in and the the CEL went away after a few engine cycles. I'm gonna be ordering a new ICP sensor now and we'll see if that improves things.