Hobert62 Posted June 29, 2016 Share Posted June 29, 2016 ok I'm this far now so how do I turn a little fuel to it? nothing to crazy just a little black smoke. Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/ Share on other sites More sharing options...
fjh Posted June 29, 2016 Share Posted June 29, 2016 Remove the 6 or 4 bolt cover at the top back loosen the rear 5/16 nut 1 half turn tighten the front nut the same amount! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337873 Share on other sites More sharing options...
Hobert62 Posted June 29, 2016 Author Share Posted June 29, 2016 24 minutes ago, fjh said: Remove the 6 or 4 bolt cover at the top back loosen the rear 5/16 nut 1 half turn tighten the front nut the same amount! In here? Are they just basically jam nuts? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337877 Share on other sites More sharing options...
Freightrain Posted June 29, 2016 Share Posted June 29, 2016 Yup, the two nuts hold the arm that controls fuel. Moving one then tighten the other back up against arm. I really cranked mine up about 14 yrs ago. Ran really well, got HORRIBLE mileage. I turned it back down and doubled the mileage(back to 8 mpg). 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337880 Share on other sites More sharing options...
Mike Posted June 29, 2016 Share Posted June 29, 2016 LOL......you can get better quarter mile times that way. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337886 Share on other sites More sharing options...
Freightrain Posted June 29, 2016 Share Posted June 29, 2016 Ya, back then I was "racing" it when the diesel drags came to town. Shortly after diesel went to $4/gal and getting 4 mpg wasn't cut'n it! I rolled the power back and got 8 mpg and just put up with the drop in power. I'm sure after it was turned up it went from 187 hp to 190 hp(at least). LOL!! Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337889 Share on other sites More sharing options...
Hobert62 Posted June 30, 2016 Author Share Posted June 30, 2016 19 hours ago, Freightrain said: Yup, the two nuts hold the arm that controls fuel. Moving one then tighten the other back up against arm. I really cranked mine up about 14 yrs ago. Ran really well, got HORRIBLE mileage. I turned it back down and doubled the mileage(back to 8 mpg). How much is really cranked it up? A half turn doesn't seem like much, but i haven't opened it up yet to understand whats going on fully either. Im use to bad gas millage my pickup is down in the single digits pretty far when hooked to the trailer and only about 10-11 driving it like a car. It's 496ci of pure gas chugging muscle. Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337952 Share on other sites More sharing options...
Freightrain Posted June 30, 2016 Share Posted June 30, 2016 Can't recall exactly how many flats I turned it but started with a couple, then thought if that is good a couple more won't hurt. Not sure if it ended up 1 full turn or what. It ran well, bob-tailing it would run away from traffic starting at a light. You can hear the snap when you crack the throttle. Once I turned it back down you could hear the "laziness" in the throttle. It was not like adding 100 hp, but it surely helps when pulling a load. Even the 1/2 turn will be noticeable. Ugh, pulling a gooseneck with a gasser. Pure torture(to the wallet). I haven't done that since 1996 with my new F350/460ci. 7 mpg pulling my race trailer. The 2000 PSD got 11 mpg. The "new" 237 gets 9 mpg. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337955 Share on other sites More sharing options...
fjh Posted June 30, 2016 Share Posted June 30, 2016 Try the half turn you'll like it 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337969 Share on other sites More sharing options...
Freightrain Posted June 30, 2016 Share Posted June 30, 2016 Just went through this with a couple local friends lately. Both turned a few flats on the nut and were pleasantly surprised with the increase. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337980 Share on other sites More sharing options...
Hobert62 Posted June 30, 2016 Author Share Posted June 30, 2016 Ok we will go with the 1/2 turn. In my head that just doesn't seam like much, but then again I don't really under stand what's going on. The garage guy that made my aero quip lines up said that a 1/2 turn makes a big difference in a cat. I guess the two are somewhat similar. Thanks all. Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337984 Share on other sites More sharing options...
Hobert62 Posted June 30, 2016 Author Share Posted June 30, 2016 5 hours ago, Freightrain said: Ugh, pulling a gooseneck with a gasser. Pure torture(to the wallet). I haven't done that since 1996 with my new F350/460ci. 7 mpg pulling my race trailer. The 2000 PSD got 11 mpg. The "new" 237 gets 9 mpg. If I take 2 tractors with 1,000 pounds of suitcase weights on each one I'm grossing right around 25,000. I'm down about 6mpg. Thankfully I don't go very far, but when it only goes 175 miles on a tank it goes quick. Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-337986 Share on other sites More sharing options...
fjh Posted July 2, 2016 Share Posted July 2, 2016 On 6/30/2016 at 0:33 PM, Hobert62 said: Ok we will go with the 1/2 turn. In my head that just doesn't seam like much, but then again I don't really under stand what's going on. The garage guy that made my aero quip lines up said that a 1/2 turn makes a big difference in a cat. I guess the two are somewhat similar. Thanks all. It Dont take much! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-338124 Share on other sites More sharing options...
Hobert62 Posted July 6, 2016 Author Share Posted July 6, 2016 On June 29, 2016 at 0:30 PM, fjh said: Remove the 6 or 4 bolt cover at the top back loosen the rear 5/16 nut 1 half turn tighten the front nut the same amount! The 2 nuts to the right of the picture right? Back the one on the left side of the arm off then tighten the nut on the right of the arm back against the first nut. Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-338624 Share on other sites More sharing options...
Hobert62 Posted July 7, 2016 Author Share Posted July 7, 2016 http://www.thedieselgarage.com/forums/attachment.php?attachmentid=11787d=1187814018 I found this link with pictures. It is the 2 nuts I thought. While looking in this part of the pump I still don't understand what's going on. Or what I'm really adjusting but I'm glad others do. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-338648 Share on other sites More sharing options...
Freightrain Posted July 7, 2016 Share Posted July 7, 2016 Ya, you got the correct ones. It's all rocket science to me too. It has to do with engine rpm and throttle position and that determines how much fuel it allows. It is a real Rube Goldberg kinda thing and I'm not really sure myself. Lord knows the new ones are likely much worse. Some how they work? 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/45849-673na-fuel-pump/#findComment-338685 Share on other sites More sharing options...
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