62bmack Posted December 5, 2009 Share Posted December 5, 2009 i am trying to figure out what the gpm of the stock fuel pump for my 1962 b-85f with a 707 gas engine. Any body have any ideas?Thanks 62bmack Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/ Share on other sites More sharing options...
Firemack Posted December 5, 2009 Share Posted December 5, 2009 Heres a ball parkAssume the 707 gets about 5 miles per gallon at road speed of 50 mph5 mpg at 50MPH =10 gal/hr10gal/hour= 10gal/60 min= .166 gal/minHope that helps, you can most likely get the actual GPM from the Mack Museum. Firemack Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/#findComment-44520 Share on other sites More sharing options...
62bmack Posted December 5, 2009 Author Share Posted December 5, 2009 Heres a ball parkAssume the 707 gets about 5 miles per gallon at road speed of 50 mph5 mpg at 50MPH =10 gal/hr10gal/hour= 10gal/60 min= .166 gal/minHope that helps, you can most likely get the actual GPM from the Mack Museum. FiremackThanks alot that did help. so here is the problem i am having with my truck. She starts fine and idles fine. accelerator pump seems to be responsive but she just runs out ofpower onder a load. I think that the pump i put on is not giving enough fuel? Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/#findComment-44536 Share on other sites More sharing options...
Firemack Posted December 6, 2009 Share Posted December 6, 2009 62BmackI had a similar problem with our B75 Pumper, I added a T in the fuel line and connected a fuel pump pressure gauage to monitor to fuel pump pressure while driving the truck, it ran out of fuel and the pressure dropped going up long hills, I sent the pump out to Kanter (in NJ) and had it it rebuilt for $88 and reinstalled it, since then never had the fuel presuure drop again. Problem solved. Maybe just to be safe send it out for a rebuild now anyway and then you know that is not the problem (if it has not already been rebuilt by a reputable shop). One other item to check is the fuel filter, I did have it run out of fuel with a clogged fuel filter, change that first and see if that is the problem before changing the fuel pump.Firemack Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/#findComment-44600 Share on other sites More sharing options...
62bmack Posted December 9, 2009 Author Share Posted December 9, 2009 62BmackI had a similar problem with our B75 Pumper, I added a T in the fuel line and connected a fuel pump pressure gauage to monitor to fuel pump pressure while driving the truck, it ran out of fuel and the pressure dropped going up long hills, I sent the pump out to Kanter (in NJ) and had it it rebuilt for $88 and reinstalled it, since then never had the fuel presuure drop again. Problem solved. Maybe just to be safe send it out for a rebuild now anyway and then you know that is not the problem (if it has not already been rebuilt by a reputable shop). One other item to check is the fuel filter, I did have it run out of fuel with a clogged fuel filter, change that first and see if that is the problem before changing the fuel pump.FiremackThanks alot for the info firemack. Sounds like fuel pump rebuild time. Do you know if the second pump was a backup or did it send fuel at the same time helping to boost pressure? Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/#findComment-44879 Share on other sites More sharing options...
Firemack Posted December 9, 2009 Share Posted December 9, 2009 62bmack,Some Mack Fire trucks do have dual fuel pumps, one electric pump at the tank and the mechanical pump on the engine. Our 1954 B75F has only has one mechanical pump on the engine so that is the one I was monitoring as it would run but then run out of fuel when under load.Firemack Quote Link to comment https://www.bigmacktrucks.com/topic/11683-fuel-pump-for-b85-with-707/#findComment-44886 Share on other sites More sharing options...
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