[Slickerthanyou]

Helping out another member who doesn't have internet access right now. He has an 89 with two pumps. He bought the gas tank out of my '90 with the one pump just in tank. The wiring he says is different, as he has three wires in his sending unit as where I have four I gave him the pigtail to the sending unit also gave him my haynes manual so I don't have any diagrams, but is it a lot of trouble to change to the one pump system? Any help/tips would be great, as he is about 70 miles away at this point.

Thanks- Bob

 

[Slickerthanyou]

Alright Steve,

Do you know or have the wiring diagram as the harness end is different and I need to see colored wires etc. I think he bought some rubber high pressure line from napa to replace it. -Bob


forget it found them on your supermotors-

 

[Slickerthanyou]

Alright the wiring is done the hose is done just one more question, The second pump on the frame will fuel flow through with out it being electrically connected? Or do we have to disconnect the hoses.Wasn't sure if there's a check valve or something that would block the flow.- Or can the second pump stay connected electrically and hydraulically. Thanks- bob

 

[Slickerthanyou]

I'd eliminate the frame pump entirely. There's no reason to still have it down there, and plenty of reasons NOT to (leaks, being the main one). He might even be able to $ell it to someone still using that system.

It's 3* outside, he is going to try it and see if everything will work with having two Hi pressures pumps temporarily or if there will be too much pressure. I don't believe it would over pressurize it as they both should only put out (40psi give or take) but was just checking. Don't want to end up with a fireball! I'll post findings for future reference.- bob

 

[BadBronc68]

i changed efi to carb setup this past weekend, put a fuel pressure reg. in place of the second pump on the framerail and everythings cake... runs plenty of pressure to the carb

 

[Fireguy50]

The wiring is easier than the fuel lines!
3 wire sending units share a ground for the pump and float
4 wire sending units have a separate ground for each
Solder the 2 grounds together to swap in the wrong tank


If you're going to swap from 2pumps to a high pressure tank pump. You should also remove that small fuel reservoir, it will screw up the tank pump from providing adequate pressure to the engine. You'll have to buy the fuel line ends and nylon line. Then make a new longer line that bypasses the unused parts.

 

[Slickerthanyou]

Update

:thumbup. All is working great, no leaks with the two pumps hooked up. :rockon.

 

[KC200787]

First off I want to thank Bob (aka Slickerthanyou) very much for the help, and I appreciate the help everyone else contributed!:thumbup

Running both is a waste of electricity (yes, it still costs gas to produce it), but you're right: their pressures won't add.

Ok, I figured they couldn't add together, but wasn't sure.

The wiring is easier than the fuel lines!
3 wire sending units share a ground for the pump and float
4 wire sending units have a separate ground for each
Solder the 2 grounds together to swap in the wrong tank


If you're going to swap from 2pumps to a high pressure tank pump. You should also remove that small fuel reservoir, it will screw up the tank pump from providing adequate pressure to the engine. You'll have to buy the fuel line ends and nylon line. Then make a new longer line that bypasses the unused parts.

Yea, the wiring was very easy, it took longer to read (for me) the two wiring diagrams than it did to splice in the other pig tail.

After Spliceing it in, tested it with the koeo and I got 12v for the red (pos) wire.

As for the fuel lines FROM the tank TO the resivor on the frame rail, they are nylon also, so Im not very concerned, but when it gets warmer outside, things under there WILL be changed.



AND:
Not entirely sure who did the write up about cutting an access panel in the floor for tank access (was it steve83?) but I did and I am very happy I cut the hole in the floor!! (Don't say that very often.)



Just one question:
Like I said above, I will change the fuel line setup as soon as I can, but I wanted to know if there will be any long term NEGITIVE effects running 2 hi pressure pumps. This setup is temporary until I have the chance to run new line for the entire fuel system. Will it last about 3 months or so?


Again, thanks for all the help!!:beer

P.S: And I think I got my vibration problems solved!:chili: (Loose pinion nut and a very very dry slip joint)