huge trouble switching tanks

deftones904 · 10-21-2009, 10:43 AM

ok we have 2 89 ford f 250s and when 1 tank runs out we flip to the other and it will stall and not restart till we purge all the air out from under the hood out of the fuel lines. which takes like 5 mins. so is somewrong or do we never let the truck run out of fuel

Case 7230 · 10-21-2009, 11:01 AM

Never let it run out of fuel. Switch tanks before that.

eponator · 10-21-2009, 11:45 AM

Seriously, never let it run out of fuel... If ya see it get on E switch tanks then and there (or if your low fuel light goes on).

The system was not designed to work the way you are currently using it. Air in the lines is also hard on the injectors.

Crmzendrgone · 10-21-2009, 12:48 PM

Agreed seems like a comment thing to switch before one tank is completely empty.

crabtruck · 10-21-2009, 05:59 PM

Letting the tanks go that low also is hard on filters/pipes/valves in fuel system
since it stirs more jumk that has settled out in tank. Encourages rust too.

deftones904 · 10-23-2009, 08:23 AM

i understand all that but are u guys saying i can fix this. cause no way back in 1989 ford made a truck that when it runs out u have to do all that **** to get it going again. our older carb trucks have no issues doing that. none of the fuel gauges work in any of the trucks so we try not to but we do run out sometimes. plus if we fill them up likly to get some sucked out at night

Case 7230 · 10-23-2009, 10:31 AM

The problem is that with an IDI diesel when it runs out of fuel the system has nothing but air in it. When you switch tanks the lift pump starts pumping fuel from the good tank but because the air can only bleed slowly from the lines and the injector pump, the injector pump cannot fill with fuel. Until it fills with fuel it will not deliver any fuel to the injectors and hence to the combustion chambers. A long period of cranking on the starter will gradually bleed the air out through the injectors allowing the injector pump to fill with fuel and hence the engine will start.
There is no way around it, other than to not let it run out of fuel.

eponator · 10-23-2009, 11:15 AM

Case7230 pretty much summed it up right there. Carbed motors work differently than these guys, just gotta get used to it.

bradrhale · 10-23-2009, 11:34 AM

repriming diesels are a pain. best way i have found is to bleed the lines up to the injectors. this is a good reason why you fill the filter up at every change before screwing it back on. otherwise, she acts like she will never start.

crabtruck · 10-23-2009, 03:19 PM

Missed the part where it said diesel ....??

10-21-2009, 10:43 AM	#1
deftones904 Junior Member Join Date: Dec 2008 Location: Columbus, OH Posts: 6	huge trouble switching tanks ok we have 2 89 ford f 250s and when 1 tank runs out we flip to the other and it will stall and not restart till we purge all the air out from under the hood out of the fuel lines. which takes like 5 mins. so is somewrong or do we never let the truck run out of fuel __________________ 1987 GMC Sierra Classic 1500 (350 throttle body injection) 1988 Izuzu Pickup (2.3L 2 barrel carb) R.I.P.

10-21-2009, 11:45 AM	#3
eponator Senior Member Join Date: Nov 2008 Location: West Covina, Ca Posts: 363	Seriously, never let it run out of fuel... If ya see it get on E switch tanks then and there (or if your low fuel light goes on). The system was not designed to work the way you are currently using it. Air in the lines is also hard on the injectors. __________________ '99 F350 5.4L crewcab Longbed

10-21-2009, 12:48 PM	#4
Crmzendrgone Senior Member Join Date: Apr 2009 Location: Arizona Posts: 1,420	Agreed seems like a comment thing to switch before one tank is completely empty. __________________ ENGINES PRODUCE POWER. MOTORS RECEIVE POWER. https://lastroundbestround.com/Home_Page.html

10-23-2009, 08:23 AM	#6
deftones904 Junior Member Join Date: Dec 2008 Location: Columbus, OH Posts: 6	i understand all that but are u guys saying i can fix this. cause no way back in 1989 ford made a truck that when it runs out u have to do all that **** to get it going again. our older carb trucks have no issues doing that. none of the fuel gauges work in any of the trucks so we try not to but we do run out sometimes. plus if we fill them up likly to get some sucked out at night __________________ 1987 GMC Sierra Classic 1500 (350 throttle body injection) 1988 Izuzu Pickup (2.3L 2 barrel carb) R.I.P.

10-23-2009, 11:15 AM	#8
eponator Senior Member Join Date: Nov 2008 Location: West Covina, Ca Posts: 363	Case7230 pretty much summed it up right there. Carbed motors work differently than these guys, just gotta get used to it. __________________ '99 F350 5.4L crewcab Longbed

10-21-2009, 11:01 AM	#2
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	Never let it run out of fuel. Switch tanks before that.

10-21-2009, 05:59 PM	#5
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,366	Letting the tanks go that low also is hard on filters/pipes/valves in fuel system since it stirs more jumk that has settled out in tank. Encourages rust too.

10-23-2009, 10:31 AM	#7
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	The problem is that with an IDI diesel when it runs out of fuel the system has nothing but air in it. When you switch tanks the lift pump starts pumping fuel from the good tank but because the air can only bleed slowly from the lines and the injector pump, the injector pump cannot fill with fuel. Until it fills with fuel it will not deliver any fuel to the injectors and hence to the combustion chambers. A long period of cranking on the starter will gradually bleed the air out through the injectors allowing the injector pump to fill with fuel and hence the engine will start. There is no way around it, other than to not let it run out of fuel.

10-23-2009, 11:34 AM	#9
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,025	repriming diesels are a pain. best way i have found is to bleed the lines up to the injectors. this is a good reason why you fill the filter up at every change before screwing it back on. otherwise, she acts like she will never start.

10-23-2009, 03:19 PM	#10
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,366	Missed the part where it said diesel ....??

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