If all goes well in this next week a 2003 2500HD 8.1L with the ZF6 will be in my garage. I have spent MANY hours here researching the 6.0 against the 8.1 and the 6.6. The 8.1 won me over. Yeah, gas mileage sucks... blah blah blah. It will still get better than my 77 K20 with a 400 and 4.10 gears. Especially in winter. :D

Lucky to find an 8.1 with a stick. Imagine driving it for another10 years, then see what the government is willing to pay to get that bad ass clunker off the road. Hell they'd probably give you a new car to get that 496 off the road!

All kidding aside, I'd love that combo, as long as I didn't have to drive too many miles. Love the stick, AND the BB.

you'll love the 8.1. i made a similar swap but i came from a '71 3/4 ton with a built 350 and 4 speed. i figured the same thing about the mileage coming from the old truck to the newer one, it might not be alot better mileage wise but all the other upgrades are worth it like the extra power, ride and cant forget about the AC. only thing i wish i woulda done was look harder for a zf/6(and no cali emissions), theres nothing wrong with the ally and its the only auto i'd own but i've always prefered the manual trans. depending on driving style i bet you'd still get around 12mpgs around town out of the 8.1/zf-6. i get 10-11 out of my 8.1/ally with a 6" lift and 35's.

that is good to hear vern650. I am wondering one thing about these trucks and didn't find anything on the forum about fuel systems (seems like everything there was just about lift pumps). Do the fuel pumps have a rough time with the 8.1? I ask because the service records show the fuel pump died twice within the first 31,000 miles, then died again at 110,000 miles. The records after that show fuel filter changes every 15,000 miles or so.

So to make the pump live longer keep changing fuel filters and don't let the tank get below 1/4? I've heard that was true for the ZR2 I used to own.

from what i've seen the fuel pumps seem to go out on all the chevy gassers around these years. i have buddies with 1/2 tons rangeing back to 97 that have lost pumps. so far mines holding up with 85000 miles on the clock and my brother just had to replace his last summer but he had 170,000 miles on his truck at the time. i've heard that if you keep clean filters in them they last longer so thats what me and my brother have been doing and so far so good.

since the truck your lookin at is an '03 i cant think of any 8.1 specific issues to keep an eye out for, (ex. the 01-02 have crank sensor issues) other than the normal little bit of oil usage. they really are a good motor and last a long time with plenty of power.

Great truck Vern, you'll love it.

The fuel pump ground which is also the ABS moduel ground is a known maintainence point. It's on the frame to body bracket just under the drivers feet. You'll see several wires grounded there on two bolts. take them loose and clean the metal really well and retighten. Then spray a hearty coating on it to keep it sealed from the weather. This will improve fuel pump and ABS life and performance. Theres a TSB that walks you through it (really simple) but also lists a new bolt, washer, and nut to replace the factory bolt. I just had ABSFixer rebuild my ABS and did the grounds TSB myself. I had just cleaned, retorqued, and sprayed the grounds in the past when my first fuel pump started acting up. My fuel gauge started wandering at about 80K. Now I'm near 140K and haven't had any other fuel pump issues. I'm pretty sure 2003 was the last year for the serviceable inline fuel filter, after that the fuel system changed to returnless and the only filter is on the pump itself.

Vernon

Good find on that truck. I have done some testing and it appears for my truck specifically I have to change the fuel filter every 6 months or so. I can always tell when its getting dirty so it easy and cheap to do. Thats alot of gas going thru there....lol.

I came from a '79 K20 lifted built SBC also. I thought I was going to be amazed at the mileage difference...well I was wrong. :D

At least its comfortable, has a/c, and pulls anything you want ;)

Great truck Vern, you'll love it.

The fuel pump ground which is also the ABS moduel ground is a known maintainence point. It's on the frame to body bracket just under the drivers feet. You'll see several wires grounded there on two bolts. take them loose and clean the metal really well and retighten. Then spray a hearty coating on it to keep it sealed from the weather. This will improve fuel pump and ABS life and performance. Theres a TSB that walks you through it (really simple) but also lists a new bolt, washer, and nut to replace the factory bolt. I just had ABSFixer rebuild my ABS and did the grounds TSB myself. I had just cleaned, retorqued, and sprayed the grounds in the past when my first fuel pump started acting up. My fuel gauge started wandering at about 80K. Now I'm near 140K and haven't had any other fuel pump issues. I'm pretty sure 2003 was the last year for the serviceable inline fuel filter, after that the fuel system changed to returnless and the only filter is on the pump itself.

Vernon

thats good info there. my fuel gauge has been all wacked out since i bought my truck and i just figured it was bad sender and figured since these are known to have pump problems i'd just deal with it til the pump decides to go. maybe i'll look into this ground point and see if cleaning it will help with the gauge, if not i'm not out nothin.

What did you spray the grounds with after cleaning them? Or would liquid electrical tape over them seal them and be good enough?

Leaving in 2 hours to start my journey to pick up the truck. It is 450 miles from here. I have all my tools, an AC delco oil filter, a fuel filter, an air filter, and some Mobile 1 high mileage oil. Will do an oil change on it right away then drive it home. Guess it has sat around a bit since winter.

When I did it the first time I just spread some zinc based anti-sieze on the connections and bolted it down tight. I probably sprayed some battery terminal protectant. These grounds are wireing eyelets that are bolted down onto the frame, you can't tape them or anything. And they stay exposed. The new 2009 TSB instructs you to buff the frame area and connectors with a Scotch-Brite Roloc Wheel or similar to get bare metal. Drill out the hole in the frame to remove the threads then install the ground lugs with a zinc plated bolt, washer, and nut torqued down to 79 lb in. Then cover the area with rubberized undercoating. That's what I did this time. The hardware material isn't special the fact that it's all zinc plated for better conductivity is so if you can find the right stuff at the hardware store that's just as good. The GM part#'s for full size trucks, suvs, and H2's are bolt: 11588564, washer: 11609679, and nut: 11609746. I think I paid around $8-$9 for them. The midsize SUV's use a different set.

Sorry for thread hi-jack, good luck with the new truck. Give us an update when you get back.

Vernon

Thanks for the info about the grounds. I'll have to look at that this weekend. And if you haven't used liquid electrical tape you should look for it. Basically think of rubber cement. It is a nasty black goo that comes in a metal small jar. Open the lid and there is a brush attached to the lid. Keep brushing it on over whatever you want to seal and it seems to stay in place for a long time.

Drove 455 miles and looked at the truck. It is in great shape! It had a utility box on it but the guy still had the original bed. So the bed is 100% new. I'm afraid to even walk inside the bed for fear of scratching the paint. Underneath was very clean. No mud caked anywhere. Slight leak from the rear diff and output shaft from the transfer case. All else is bone dry. The OEM shocks are shot. Front floats around. Headlights pitted, windshield cracked. Small hole in seat... but very small things for $6950. Yes, $6,950. I have full service records also.

The tires are shot, so the drive back was kept at 65 mph. Very boring. I filled up there and again once I got back. 455 miles on 3/4 tank. Averaged 16.8 mpg. I kid you not. This included going over the divide. The truck is amazingly quiet. Too quiet if you ask me. I stalled it twice not being able to hear the motor and lugged it too much. I'm amazed that a 2500HD can have road manners on the highway.

The back of it might be too tall for my 5th wheel. It is 58" to the top of the tailgate. Old truck was 53". It has the optional heavy duty leaf springs on it and that seems to raise the rear 2-3" The raked look it has is just silly looking (with the 245 tires).

Thanks all- I do have questions but I'll use the correct forums.

Thanks for the info about the grounds. I'll have to look at that this weekend. And if you haven't used liquid electrical tape you should look for it. Basically think of rubber cement. It is a nasty black goo that comes in a metal small jar. Open the lid and there is a brush attached to the lid. Keep brushing it on over whatever you want to seal and it seems to stay in place for a long time.

Drove 455 miles and looked at the truck. It is in great shape! It had a utility box on it but the guy still had the original bed. So the bed is 100% new. I'm afraid to even walk inside the bed for fear of scratching the paint. Underneath was very clean. No mud caked anywhere. Slight leak from the rear diff and output shaft from the transfer case. All else is bone dry. The OEM shocks are shot. Front floats around. Headlights pitted, windshield cracked. Small hole in seat... but very small things for $6950. Yes, $6,950. I have full service records also.

The tires are shot, so the drive back was kept at 65 mph. Very boring. I filled up there and again once I got back. 455 miles on 3/4 tank. Averaged 16.8 mpg. I kid you not. This included going over the divide. The truck is amazingly quiet. Too quiet if you ask me. I stalled it twice not being able to hear the motor and lugged it too much. I'm amazed that a 2500HD can have road manners on the highway.

The back of it might be too tall for my 5th wheel. It is 58" to the top of the tailgate. Old truck was 53". It has the optional heavy duty leaf springs on it and that seems to raise the rear 2-3" The raked look it has is just silly looking (with the 245 tires).

Thanks all- I do have questions but I'll use the correct forums.

455 miles = 732.25152 kilometers, I can only get around 430km draining the tank,out of a tank with my short box you must have a long box.

Welcome to the forum. Lots of good HD information to be had around here. Those 8.1L are good runners.

455 miles = 732.25152 kilometers, I can only get around 430km draining the tank,out of a tank with my short box you must have a long box.

Yep, a long box. Running around here the last couple days I'm not getting near that for short trips.

Shit Id be a happy mofo is I could see 200 out of a tank in town

I see 300 on highway sometimes.

Do yourself the biggest favor and get a custom tune for it. That will make all the difference, trust me. The oem tune is dumbed way down to limit power output and throttle response.
Oh, and I get about 8mpg driving around in the city with a lead foot. It's just too much fun to resist!


:HiHi:

congrats on the new truck. get some pics up for us to check out.

Do yourself the biggest favor and get a custom tune for it. That will make all the difference, trust me. The oem tune is dumbed way down to limit power output and throttle response.
Oh, and I get about 8mpg driving around in the city with a lead foot. It's just too much fun to resist!


:HiHi:

That is on the list of things to get done. My money tree is badly pruned back right now. :D Still seems odd that GM made such a great motor and then limits the crap out of it. It went up the passes like they weren't even there, but when getting on it to pass a car on the highway I was just expecting more.

I do have a few pics in my garage folder.

Partial list of things to do still:
reciever hitch
5th wheel hitch
brake controller
5100 Bilsteins
window tint
custom tune (get rid of the TM!)
aftermarket muffler

I figured I'd post a 2.5 month update on this truck. I still love it. Found the thermostat was stuck open- but that was it for broken parts.

I did a blackbear tune, lifted up the front a bit, new Revo 265's, OEM 6 disc radio, full tune up with new wires, 5100 shocks, removed decals from the bed, tinted door windows, and other stuff. :D
I was very impressed with the speed that I got the PCM back. I shipped it out (USPS priority)Tuesday morning from MT shipped it out and it was back by Saturday. Truck really woke up- especially at lower speeds.


Last weekend I did another road trip on the highway: 371.9 miles on 23.597 gallons... 15.76 mpg. This included a small bit of city driving and was done over 3 days- so I figure I lost a small bit of gas mileage on a cold motor and the stop lights. Speed limit on the highway is 65, so this helped I'm sure.
Driving to and from work which is probably a 50/50 mix of highway/city I was getting around 13. I'm keeping a log in the glove box of each tank. I don't have a trip computer so all calculations are done by hand.

Best tank I ever had with the '77 was 12 mpg and that was doing 55 or so in poor weather on the highway.

Damn I couldnt get 13 city to save my life.

Nice truck,like the 6 speed