Farmer Joe Posted July 13, 2011 Report Share Posted July 13, 2011 so for the last 2 summers ive been having an issue with the kingcab.. most days that its hotter than maybe 75-80 deg, my fuel pump starves out of fuel, and makes the truck act like it ran out of gas. the first thing i wanna find out is, what is vapor locking? is this whats happening here? since ive put the fuel cell in the truck, the way i can fix it is blowing into the tanks breather to push fuel back through the lines.. the pump starts pushin fuel again, and we all good. now this only happens when it just really hot outside.. my first theory was that the truck was too low to the super hot asphalt, thus boiling the fuel in the pump, and the lines.. still thinkin that might be it.. another theory was that the pump is overheating and just loosing its prime.. anyone else got any input on this? any help would be cool! thanks Quote Link to comment
Wide14u Posted July 13, 2011 Report Share Posted July 13, 2011 maybe just an old pump Quote Link to comment
I'm BLUE Posted July 13, 2011 Report Share Posted July 13, 2011 Have you considered the "routing" of your exhaust in relation to fuel lines as well ? :) Are you coolant passages to your intake "flowing" properly ( not clogged ) ? Wrap your Fuel lines in insulation and install heat-shields ? ( or header wrap your damn exhaust "if" it's the exhaust ) :lol: ^^^ I guess a lot of my advice is irrelevant if your fuel cell is installed in bed of truck ( above ) :) Quote Link to comment
Farmer Joe Posted July 13, 2011 Author Report Share Posted July 13, 2011 well the exhaust is not an issue.. its on the outside of the frame on the driver side.. totally out of the way. i was thinking about a new pump... theyre kinda spendy tho... gonna have to wait till next paycheck. sickboy1031 said to put some of that insulation that race cars use on the fuel lines.. more spendy stuff... one of those stupid problems i dont wanna troubleshoot. Quote Link to comment
RedBanner Posted July 13, 2011 Report Share Posted July 13, 2011 Had a problem kinda like that on my first b210, changed alot of things without xhecking the whole situation, ended up being either a small hole I found in the line near the tank, or I removed an obstruxtion when I blew my lines out. The thing is the hole in my line wasnt big enoughf to leak but I think air could get sucked in, it deff leaked with 140 psi blastin through it. Quote Link to comment
Z-train Posted July 13, 2011 Report Share Posted July 13, 2011 Does the 77 have a return line? Quote Link to comment
racerx Posted July 13, 2011 Report Share Posted July 13, 2011 Have you checked/changed your fuel filter? I weird thing happened to my 510 several months ago. Car died and would start for a little bit but when I stepped on the gas the car would die, then start later again but would not budge. Cheange my fuel filter, fuel pump..still not working. So I took out the gas tank peeked inside and lo and behold silicon plugged up the pick up tube. Not sure how it got there but I'm assuming the guy before me siliconed the gas sensor area and silicon went inside the gas tank..maybe you can ran some compress air through the gas line before the gas filter and open the gas cap...good luck. Quote Link to comment
Farmer Joe Posted July 13, 2011 Author Report Share Posted July 13, 2011 no nothings clogged. the fiters are new. if i take the line fuel line off the carb when this happens, a stream of vapor comes out. you cant see it see it, but theres the slightest bit of pressure and fuel vapor is shooting out. blow the fumes out of the line and the liquid fuel starts flowing again.. Quote Link to comment
datzenmike Posted July 13, 2011 Report Share Posted July 13, 2011 The L20B motors got the return line for just that purpose. They rum hotter under the hood and the gas will boil in the lines and/or carbs making restart difficult. Theretirn line has a pinhole restricter in it so the pump can build pressure up against it and flow into the carb. Without the restrictioon the gas would simply flow past the carb and back into the ttank. The return line keeps cooler gas from the tank flowing past the carb. Any vapor bubbles would be pushed back into te tank. Quote Link to comment
ggzilla Posted July 13, 2011 Report Share Posted July 13, 2011 What is the definition of vapor lock? Just what you described, fuel vaporizes in the fuel line, and since vapor is compressible, it won't pump the fuel any longer. Early Datsuns had this problem. For example, the 320 Pickup had an abestos shield on top of the fuel pump facing the exhaust manifold, if this falls off or is removed occasionally it will vapor lock. Datsun solved this problem by fitting a fuel tank return line to later models. That way the fuel keeps moving and doesn't overheat. And of course by not routing lines close to hotspots like the exhaust. Quote Link to comment
Farmer Joe Posted July 13, 2011 Author Report Share Posted July 13, 2011 well its good to know this then... well ill have to see if the motor craft carb has a return prevision.. either that or setup a hose system that will allow pressure and return to the tank... Quote Link to comment
hobbes_the_cat Posted July 13, 2011 Report Share Posted July 13, 2011 I had the same problem in a 64 ford. I wrapped the fuel line in the engine bay with hi temp foil backed insulation. Fixed the problem. Quote Link to comment
ggzilla Posted July 13, 2011 Report Share Posted July 13, 2011 Aluminum foil and duct tape will work too. Quote Link to comment
datzenmike Posted July 14, 2011 Report Share Posted July 14, 2011 well its good to know this then... well ill have to see if the motor craft carb has a return prevision.. either that or setup a hose system that will allow pressure and return to the tank... You have a '77? then it has a return line. If you modified the tank maybe it was left off and closed. Loss of suction could be a leak allowing air into the line Quote Link to comment
Farmer Joe Posted July 14, 2011 Author Report Share Posted July 14, 2011 You have a '77? then it has a return line. If you modified the tank maybe it was left off and closed. Loss of suction could be a leak allowing air into the line i think i might have removed the most of the return line when i had the bed off the truck last. i got rid of alot of those vent lines.. really figured i only needed just a fuel line. with dailying the stupid thing everyday, i dont have alot of find out what i cant do time lol Quote Link to comment
Farmer Joe Posted July 25, 2011 Author Report Share Posted July 25, 2011 had some time and looked into this a little further this evening.. found a leak where the line from the tank was going to the pump inlet... now i know what there streaks next to the truck were... gas disolving the tar on the road.. in any case, got that leak stopped, and then took all the little bit of foil i had and wrapped up the line from the tank to the pump. then kind make a sorta shell around the clicker fuel pump to keep the road heat away maybe... drove it around a little this evening, and it was still prolly 80-85, and even in the drive through for dinner it didnt lock up... maybe some progress.. well see tomorrow when i get off work at 3... they said its supposed to be like 100.. ugg... Quote Link to comment
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