'85 720 fuel diagram needed

[Raggleflaggle]

18 hours ago, datzenmike said:

Just to be absolutely clear it connects to a port on the base of the carburetor not the intake. 

maybe my source has led me astray. i have everything hooked up as described in that link. 

and i think it did leave me with a connection at the base of the carb to plug. 

18 hours ago, datzenmike said:

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.

exhaust side has no spark, tested at the coil HT output. absolutely nothing. 

would prefer it to be a fuse. thanks for the heads up!

[datzenmike]

3 minutes ago, Raggleflaggle said:

maybe my source has led me astray. i have everything hooked up as described in that link. 

and i think it did leave me with a connection at the base of the carb to plug. 

 

 

 The front most one goes to the vacuum advance on the distributor, with a Tee to the Vacuum Control Valve.

[Raggleflaggle]

my vaccum advance goes: dist > middle hardline across front of motor > soft line to port on intake. i'll get a pic at some point but it is currently hooked up where that writeup tells me it goes. 

[datzenmike]

What write up? I only know the stock Nissan connections. Is that not what you're after? Intake vacuum for distributor advance was last used in the late '60s and will be too high for later distributors.

[Raggleflaggle]

On 6/7/2023 at 8:28 PM, Raggleflaggle said:

 

On 6/7/2023 at 8:28 PM, Raggleflaggle said:

 

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

 

 

[datzenmike]

It's wrong or mistaken

 

 

Follow the vacuum advance hose back from the distributor. At no point does it connect to the intake. It splits to the vacuum control valve on the left and the T V V (thermal vacuum valve) on the right which prevents vacuum from getting through to the distributor till engine is warmed up.  The other hose is open to the air filter and the third hose goes to the port on the carburetor.

[Raggleflaggle]

this makes some sense... was likely hooked up right to start with. 

[Raggleflaggle]

Mike was right. Saved me from a 18$ Rockauto coil. 

 

turns out the #1 fuse and part of the fuse box under #1 fuse were broken. when holding a 15A fuse in place and cranking it up, it now starts up immediately. doesn't run well or stay running, but, progress.

 

Vaccum hose routing is now IAW with the diagram posted here, just need to go ahead and get another 10-15 ft of hose to finish replacing all the lines one by one. luckily i have had all the right vac connectors. 

 

if anyone has an original hitachi (or whatever this came with) i'm interested in it, at least if just some pictures of how all the electromabobs on the carb look and are wired up. still unsure of what the ICM on this does with that information or how it effects spark delivery. 

[datzenmike]

If it's been on just the one side the owner may have advanced the timing to get it to run. Dual coils mean a shorter burn time so check that it's 3 degrees BTDC.

 

43 minutes ago, Raggleflaggle said:

Mike was right. Saved me from a 18$ Rockauto coil. 

 

turns out the #1 fuse and part of the fuse box under #1 fuse were broken. when holding a 15A fuse in place and cranking it up, it now starts up immediately. doesn't run well or stay running, but, progress.

 

Vaccum hose routing is now IAW with the diagram posted here, just need to go ahead and get another 10-15 ft of hose to finish replacing all the lines one by one. luckily i have had all the right vac connectors. 

 

if anyone has an original hitachi (or whatever this came with) i'm interested in it, at least if just some pictures of how all the electromabobs on the carb look and are wired up. still unsure of what the ICM on this does with that information or how it effects spark delivery. 

 

 

Once warmed up, according to the water temperature sensor, ( not the temp gauge) open loop changes too closed loop where the feedback from O² sensor is taken into account and the mixture solenoid tightly controls the air/fuel ratio for best economy and emissions. Idle and full throttle position switches over ride this. Clutch and transmission switches plus closed throttle switch allow the idle cut solenoid to be turned off during deceleration to reduce unburned hydrocarbons and save gas.

 

Distributor timing and advance are solely the job of the distributor. The ECU just needs a tach signal to know haw fast the engine is turning

[Raggleflaggle]

On 6/15/2023 at 3:03 PM, datzenmike said:

If it's been on just the one side the owner may have advanced the timing to get it to run. Dual coils mean a shorter burn time so check that it's 3 degrees BTDC.

 

i was just about to question this! gonna check that. 

On 6/15/2023 at 3:03 PM, datzenmike said:

Once warmed up, according to the water temperature sensor, ( not the temp gauge) 

i'm sure i can figure out where this is, but whAt is operating range for this? how do i tell which sensor is for the dash and which is for ECU?

 

On 6/15/2023 at 3:03 PM, datzenmike said:

the mixture solenoid tightly controls the air/fuel ratio for best economy and emissions. Idle and full throttle position switches over ride this. 

so if there is no TPS on the new carb, the truck has no idea when to disregard inputs which it may or may not be getting useable inputs from. 

 

it could be stuck in some limp mode or equivalent assumed value. can it even detect values that are out of range or nonexistant and choose to ignore them?

On 6/15/2023 at 3:03 PM, datzenmike said:

Clutch and transmission switches plus closed throttle switch allow the idle cut solenoid to be turned off during deceleration to reduce unburned hydrocarbons and save gas.

so i was assuming that the antideseling sol. on the carb is equal to a fuel control solenoid, but it seems this is not the case. (assuming that's what the one wire sol. in previous pics is)

 

if ignition management is totally independent, and the ECC's only way of acting on the inputs of the various sensors is with a sol. that i may not even have on this carb, what do you suggest is the most budget friendly way to sort this out? 

[Raggleflaggle]

to clarify, gold thing with red wire is the solenoid i'm referring to.

 

the carb came on the truck, so i can't verify 100% this is what the PO bought. but it sure looks like it. 

 

https://www.amazon.com/MOSTPLUS-16010-21G61-1601021G61-Carburetor-Compatible/dp/B089YKNGYG/ref=asc_df_B089YKNGYG?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80401905949293&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=m&hvlocint=&hvlocphy=&hvtargid=pla-4584001431893404&psc=1

[NC85ST]

Don’t overthink it. I ran a carb off of an ‘84 on my ‘85 for years with everything capped off except a vacuum line to the distributor and the only wire was to the choke. I’m guessing that Chinese carburetor is a big part of your problems.

[datzenmike]

3 hours ago, NC85ST said:

Don’t overthink it. I ran a carb off of an ‘84 on my ‘85 for years with everything capped off except a vacuum line to the distributor and the only wire was to the choke. I’m guessing that Chinese carburetor is a big part of your problems.

 

Was it a regular carburetor or the ECC feedback carburetor with the 6 wire electrical plug?

 

 

If this is disconnected and only the choke and the idle cut kept, it will revert to 'limp home' mode which is an over rich condition to prevent any chance of an accidental over lean mixture that could fry the pistons. Limp home mode has terrible mileage.

 

 Raggle the vacuum hose (EGR?) looks like it's split where it's connected to the port on the carburetor base.

 

20 hours ago, Raggleflaggle said:

 

 

 

[NC85ST]

20 hours ago, datzenmike said:

Was it a regular carburetor or the ECC feedback carburetor with the 6 wire electrical plug?

 

The carburetor itself, I don’t remember, but I don’t think so. Did they have a feedback carburetor in ‘84? The truck, a ‘85, was 6 wire. 

[Raggleflaggle]

On 6/17/2023 at 9:27 AM, NC85ST said:

Don’t overthink it. I ran a carb off of an ‘84 on my ‘85 for years with everything capped off except a vacuum line to the distributor and the only wire was to the choke. I’m guessing that Chinese carburetor is a big part of your problems.

if your '85 had an ECC, and it worked with a non ECC, i'd very much like to know more about how that was set up. 

Edited June 18, 2023 by Raggleflaggle

[Raggleflaggle]

it does look like it there, but it's a new hose. 

[Raggleflaggle]

On 6/17/2023 at 12:49 PM, datzenmike said:

 

If this is disconnected and only the choke and the idle cut kept, it will revert to 'limp home' mode which is an over rich condition to prevent any chance of an accidental over lean mixture that could fry the pistons. Limp home mode has terrible mileage.

how does the truck control if it is in limp mode? using a fuel solenoid that the current carb doesn't have? 

[datzenmike]

This is why I asked which carburetor you have. If it was an ECC and you put a regular carburetor on and only keep the idle cut and the choke it will run like a regular carburetor.

[Raggleflaggle]

turns out some of my issue was ignition side problems, new cap and rotor and it fired right up.

 

prev. cap and rotor were new, but had black plastic, and silver contacts. never seen that before. New parts have bronze colored contacts.

I didn't think chinesium was an actual different materal, i just thought it was a metaphor for poor quality control...