720 electric fuel pump ?'s

[Pacific coast Datsun]

I just mounted & wired up a 720 electric fuel pump on my 620 & im having an issue. The pump is'nt pumping enough gas up into the filter in the engine bay. Yes theres gas in the tank & yes i have the hoses on the pump hooked up correct. I even tried running it without the filter thinking it was clogged, got the same results. I spoke to a mechanic friend & he said the diaphram may have went bad if the pump has sat for a long time.

My ? is are these factory pumps rebuildable or should i buy a generic replacement from O"reileys ?

[Pacific coast Datsun]

Anybody with info ? Just hoping i can rebuild the stock one...

[datsunaholic]

Well, do a write-up on how to do it since I sure can't find parts to fix those. Kind of a "replace" rather than "repair" item.

[Pacific coast Datsun]

Well, do a write-up on how to do it since I sure can't find parts to fix those. Kind of a "replace" rather than "repair" item.

ummmm ok ? ill replace it with another NEW pump when $$$ allows.

[datsunaholic]

Ugh, that came across harsh and that's not how I meant to sound.

 

What I meant was, if you can find the parts let us know. I've never seen any repair parts for them. I don't even know how to take them apart without breaking them.

 

I have 3 dead stock Nissan pumps, and due to being unable to find any decent aftermarket pumps I've got one of those square buzzbox POS's from CSK O'Reilly's. The Nissan ones seemed to last about 200,000-300,000 miles if used all the time; the Chinese junk lasts about a year, 10,000 miles between failures. Pretty much just like the aftermarket mechanical fuel pumps. I've taken to grabbing ones off junkyard trucks and self-testing them at the junkyard's battery rack. If they move air, they'll move fuel. Maybe not well, but it's a test, and it beats the $150 or so a new Nissan one costs.

[Pacific coast Datsun]

Ugh, that came across harsh and that's not how I meant to sound.

 

What I meant was, if you can find the parts let us know. I've never seen any repair parts for them. I don't even know how to take them apart without breaking them.

 

I have 3 dead stock Nissan pumps, and due to being unable to find any decent aftermarket pumps I've got one of those square buzzbox POS's from CSK O'Reilly's. The Nissan ones seemed to last about 200,000-300,000 miles if used all the time; the Chinese junk lasts about a year, 10,000 miles between failures. Pretty much just like the aftermarket mechanical fuel pumps. I've taken to grabbing ones off junkyard trucks and self-testing them at the junkyard's battery rack. If they move air, they'll move fuel. Maybe not well, but it's a test, and it beats the $150 or so a new Nissan one costs.

No offense taken Doug,,just frustrated after spending a few hours fabbing brackets so i can run the 720 pump just to have it fail.

I priced a cheapo aftermarket pump @ Kragen for $60. New factory ones off E-bay go for $150-ish ! :blink:

[datzenmike]

Unscrew the bottom, there a filter and magnet inside. There should also be an in line filter between it and the tank. Be sure you have a good size power wire to reduce any voltage drop.

 

Undo the outlet hose on the pump and turn it on. Does it pump a good stream? If so perhaps the fuel line is filled with sediment, kinked?

 

You can disassemble somewhat. When standing upright the pump contains:

 

plunger

return spring

inlet valve

O ring

washer

spring retainer

gasket

filter

cover casket

magnet

twist on cover. (bottom)

 

The internal filter can be carefully washed in clean gas and re installed. The filter # is 16404 28530 under $10

[Pacific coast Datsun]

TY Mike. I ran jumper wires right off the pump to a car battery that was on the floor, they were less than 2 feet long...

You can hear the pump vibrate like it's working.........

Ran it for at least 3 minutes & looked in the fuel filter in the engine bay...it started to fill then the gas drained out of it........

The outlet line was not kinked & the rest of the fuel line is all new.

[banzai510(hainz)]

Dont know the cost. but these are good

I have a Mallory from the prev Owner. Its over 25 years old. still going good. also has a Dial reg turn down to 3 3.5 pounds

 

http://www.malloryperformance.com/ProductDetails.aspx?modelNumber=4070LP&productID=2562&majID=570&minID=5703&selection=6&minselection=2

[Pacific coast Datsun]

TY for the link Hainz. Theres a few shops close to me that sell it too.Im hopefully picking up a new "used" pump tonight from a Ratsun member, ill keep you posted.