'85 720 fuel diagram needed

[Raggleflaggle]

Recently acquired a 720 that has been sitting up for some years. Made the mistake of leaving the old gas in it, as well as attempting to run it on said fuel mixed with about 4 gallons of 2 month old fuel from a gas can. 

 

after realizing a good portion of this fuel is definitely water, and now not hearing the return line piss in the tank with the pump running(as it did initially) I'm thinking it's a bit past "put some HEET in it" time and maybe more "go ahead and sort out the fuel system properly"

 

TL,DR: ISO late '85 model z24 singe cab short bed fuel system diagram with legible part numbers. 🙏

[datzenmike]

Change the fuel filters first. There's one between tank and electric pump. The bottom of the electric pump twists off and there is a filter there also as well as a magnet. This may, or may not help but they are going to need replacing anyway.

[Raggleflaggle]

truck came with the pre-pump filter already replaced, but i'll bet the other is in dire need. is there a seal that goes with it, or anything else fuel related that's not intuitive? (I.E. fuel pump relay/cutoff)

 

also i'm noticing a drip coming down the inside of the wire protector on the pump's wire harness. i assume that will make plenty of sense once the tank gets dropped..? 🤷‍♂️ 

 

should i get an fsm for an '85? would that have the diagrams and part numbers? I assume a chilton/haynes won't. 

[datzenmike]

Well in theory the one in the pump should never get dirty because it has to go through a filter before it gets there right? I think the manufacturer (not Nissan but a supplier) does it just to be sure the pump is protected.

 

I would definitely get the Nissan FSM and not at all those others. None of them even the FSM have part numbers.

[Raggleflaggle]

i can find some stuff for Zs and 510s. 

https://www.ebay.com/itm/NISMO-Electric-Fuel-Pump-Replacement-Filter-For-DATSUN-NISSAN-510-1200-240Z-/371636801676

 

figure that will work? 

 

where do you all get part #s and diagrams from?

been off the forum a good while. spoiled by the likes of realOEM.

 

 

do i have to go to the PNW and speak latin to a robed figure in what used to be a Datsun dealer (but now sells one off, organic, non-gmo, gluten free cookies and used books) and hope the armed amazon security drone patrols don't catch me trying to repair stuff?

[Crashtd420]

Being an 85 I think the dealer can still look things up... not 100% sure what year their cutoff is....

 

I use this sight for parts at times... plenty of diagrams....

https://www.nissanpartsdeal.com/1985-nissan-720_pickup-parts.html

[Crashtd420]

[Crashtd420]

On ebay....

That 16404-28530 come up with many results....

 

This one is right from the dealer...

https://www.ebay.com/itm/201331031042?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=DzWCZ5ZUSGi&sssrc=2349624&ssuid=2B08jY5FRkS&var=&widget_ver=artemis&media=COPY

[NC85ST]

Don’t forget to get rubber seal also, because it doesn’t come with the filter.

[Raggleflaggle]

Hell yeah man.👍👍 that's mad cheaper and and nissan specific distributor to boot. Exactly what I needed!! The truck thanks you in advance!

[Thomas Perkins]

Go to Nissan Parts Deal.com and you will find your pictured part with part number and price if they still have it.You can also may find them on Ebay with free shipping..I sometime use Courtesy Nissan Parts.com because their shipping is cheaper and sometimes they sell on Ebay.Hard to find parts are found on over seas Nissan dealers.I have bought from them.Shipping is more but they have parts that can't be found in USA..Need help.let me know.I have a few extras of those little filters that go into the fuel pump.You can use your old rubber gasket and magnet.The last time I changed both filters I used the rubber gasket.I don't have any filters for sale.I never had one that was clogged up.I changed it when I change the big fuel filter.That is the one that will get clogged up.The small one in the Weber has never got any particles in it.My FSM has no part numbers.Nissan has run out of Fuel pumps.I have a new extra one that I am not selling.I have a old one that does not work.I could not get it to work.I put a new 2 filters in and it would not work.Them little filters are everywhere.Try Ebay first cause of the free shipping.Also change all your rubber gas lines starting at the gas tank.Their are 2 by the starter.I think they are 5/16.Also use new hose clamps.I use a Weber so my rubber hose connects to the metal line just below it and the hose is about 5 inches or so.Make sure your fuel lines at the fuel pump are in the right place.Need pictures,let me know.

Edited June 2, 2023 by Thomas Perkins

[Raggleflaggle]

I'm struggling with the filter cap on the fuel pump, looks like it's likely never been removed. hopefully i don't end up rounding it off.

I spent some time sorting out the vac lines and thanks to some threads on here its all connected properly. 

looks like the carb was replaced with ethier the wrong variant or a cheap knockoff, as i can't find any manufacturer castings. the anti-dieseling solenoid has a different two blade connector that has been spliced into a single wire on the harness' cannon plug.

 

[datzenmike]

There is also a very fine brass screen at the fuel line banjo fitting to the carburetor. Plastic screen today.

[Raggleflaggle]

i'd assume if there is a filter inside the carb it's new too, but easy enough to check. 

 

i've found the listing for this same carb on amazon, for 100$ i'm thinking someone just threw parts at it and then gave up. Still wondering what all those other pins on that plug do, but i guess the FSM will tell me when it gets here.

 

how does this regulate fuel pressure? read something about the return hose being a different diameter to reduce flow or something.

Edited June 5, 2023 by Raggleflaggle

[datzenmike]

You have an ECC (electronic controlled carburetor) or feedback carburetor which is a cross between a carburetor and EFI. It controlled by an ECU under the driver's seat and needs a tach signal, water temp, 0² sensor, throttle position closed and full open switches, +12 v battery, neutral transmission switch and clutch switch to calculate the on/off rate of the air/fuel mixture solenoid in the primary barrel.

 

 

[Raggleflaggle]

maybe it originally had one. 

 

i believe the truck is pretty base model, no tach in the cluster. 

it does have some very primitive looking single wire sensor in the exhaust manifold. 

also to further complicate things, it seems to have had a salvage motor put in, paint marked to be an 85. 

 

is there any reason why i can't just run this non-ECC on an(assumably) ECC fuel system? 

[NC85ST]

17 hours ago, Raggleflaggle said:

I'm struggling with the filter cap on the fuel pump, looks like it's likely never been removed. hopefully i don't end up rounding it off.

I had the same problem. After removing the pump from the truck, I used a wire wheel around the cap and then sprayed PB Blaster around it and let it sit for a bit, before putting a socket on it. It worked for me, maybe it would for you.

[Raggleflaggle]

next time i go out there i'll have to try that. likely my best chance, hopefully i'm not shopping for a new NLA pump soon. 

[NC85ST]

If the pump is bad, you can use any electric fuel pump designed for use with a carburetor. I used the pigtail from a factory pump on a Holley fuel pump so that I didn’t have to butcher the wiring on the truck. It worked fine, even mounted it where the factory pump was.

[datzenmike]

By tach signal I didn't mean you needed a tach just the ignition pulses so the ECU knows the RPM.

 

Make sure pump pressure is not above 4 PSI. Some go as high as 7-8 PSI. Too much pressure will overpower the needle valve and flood the carburetor.

[Raggleflaggle]

okay, so ecu runs off the tach signal from coil then, i'd assume. 

 

being that it can't adjust injection timing as there is no injection, can it control ignition? distributor is vaccum advanced, does it somehow alter vaccum signal to the dist. to effect change?(doesn't look like it can)

if it is expecting these inputs and not recieving some of them, what does it do?

[datzenmike]

Distributor ignition is totally separate and follows the mechanical and vacuum advance that is built into them.

 

The carburetor has a port that generates a vacuum signal. It's engine load dependent with high vacuum signal at light throttle and little to no signal at full throttle. The distributor's vacuum advance simply advances the timing at part throttle and removes any advance at full throttle.

[Raggleflaggle]

ok, the vac. adv. is hooked up to the intake as recommended here

https://www.nicoclub.com/archives/nissan-720-pickup-truck-vacuum-hose-routing-and-repair-guide-part-2.html

 

iVe verfied fuel flow (not pressure, just that it's not blocked/restricted) on the return line. 

still waiting on the in-pump filter, and the fsm. 

 

have also noted new plug wires, plugs, and a bad lower ignition coil. 🤷‍♂️ guess this is gonna be an expensive "cheap" truck.

 

[datzenmike]

Just to be absolutely clear it connects to a port on the base of the carburetor not the intake. Of the three ported vacuum sources on the carburetor, the vacuum advance should be the front most one. The middle one is the purge signal for the charcoal canister and the rear most is for the EGR.

 

NGK BPR6ES for the intake side

NGK BPR5ES for the exhaust side.

 

How do you know one of the coils is bad????? If exhaust side not firing it's a blown #1 fuse the one on the far left of the fuse box. Only replace the coil if there is no spark. Otherwise leave alone.

[Thomas Perkins]

Your carb is real shiny.I have a Brand new Fram air filter.A brand new Nissan wing nut and brand new  Nissan rubber fitting that goes under the wing nut.I believe it connects to the top of the air breather top.Part numbers are 16561 and 16568.Nissan has no more of these.They are still in Nissan package.I probably still have the Nissan receipt from when I bought it long ago.That's if you want original parts .Fram filter came from Walmart.I now have a Weber,so these parts are no good to me.I also have a brand new Nissan still in package white blower resistor.Bought it long ago and they gave me the wrong one.It is a 3 speed type.Mine is the black one but I no longer use the old blower motor.Also have the used blower motor,but no wheel for sale.Got some like new,used Ngk Spark plugs for sale.I use the Ngk Iriduim type.If any one wants these,let me know.I am not going to post it on the for sale place here.

Edited June 8, 2023 by Thomas Perkins