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Will a mechanical pump pull through electric pumps
First let me say, im not looking for the debate over EFI and carb lol, that bridge has already been crossed. I have 92 dual tanks that I am hooking to a carb motor. I bought a valve to switch between tanks. I took apart the sending unit today to see about by passing the pumps. I could do it although it won't be easy. I need to leave the plastic housing intact to keep the gauges working. So I was poking around, and heard some hearsay that the mech pump would pull through the electrics if I just disconnect the wiring. So does anyone know this for sure? I really don't want to pull both tanks again after I get this thing together. Seems like it would as I have used inline electrics to pull through intank electrics before, but that was in a Mazda, an I'm sure the electrics have more pull than mech.
I used an 89 van fuel tank and electric pump on my 1983 460 E350 RV with a mechanical pump on the engine and it pulled through OK but the 1989 tank pump did not have any check valves in it but the 1992 FDM does have.
I ran the electric pump only in the Mountains but was off at other times.
You should be fine. I ran an aftermarket rail-mounted pump for about a year with non-functioning in-tank pumps. If you are worried about it and have the time, you could pull the in-tank pumps, remove the pump itself from the housing and replace it with a piece of tubing so you still pull fuel from the bottom of the tank.
I converted my Motorsports engine to EFI. I don't understand the backwards move by why not use the electric pump(s) with a pressure regulator and return line?
Well it would costs more to switch to electric, and I can change the mechanical pump in less time, and not have to deal with whatever fuel happens to be in the tank. Granted changing the mech isn't the easiest, I prefer it to dropping a tank. And one can always remove the bed to work on electrics, but in my experience 2 out of 3 beds, the bolts have to be cut/ground to be removed.
It's not as simple as pull the pump from the housing and add some tubing. The pump has an odd shaped grommet which fits into an odd shape in the plastic housing, and it appears alot of plumbing is part of the plastic housing. It's strange. The pump doesn't connect directly to a line, nor is that line directly above the pump on the housing.
I'm not sure on fuel pumps, but I would assume the check valve would be right at the exit port on the pump. I could probably drill it out if it is a problem. I was thinking too, I'll just wait til everything is working before I put the bed on
Yep, that's it. So that's where the check valve is, and being "high pressure", looks like surgery will be on the schedule...or maybe "high pressure" is just describing the fuel pump. Guess I can wait til it's all together to find out
I gutted both types of in tank pumps once. The low pressure ones(85 to 91) are a centrifugal type impeller and the high pressure(91 and up) ones are a roller vane type.
Fuel will pull past the centrifugal impeller but not the roller vane type impeller.
Good catch - it is a 1987, originally a 5.8L. Completely different pump. Is the wiring harness the same shape for the high and low pressure pumps? If so, you could do low pressure pumps in the tank and a mechanical pump on the engine. Disconnect power to the low pressure pump and you have an easy backup in case the mechanical pump ever fails, but you still have the benefit of gauges working. Or not.....just spit ballin' here. I like redundancy where possible.
Well I think I have it figured out. The front tank was pretty easy
The rear was a little tougher. I could do it now without destroying the plastic housing, but some trial and error lead to some destruction to figure it out
