I have returned... Question regarding off-idle Hitachi stumble

[A guy named Rick]

Ratsun community, I have returned. So, smog time has come and I took the weber off and swapped a hitachi on. This wasn't as easy as I thought, but the truck runs fairly well. I'm quite surprised, as I never fully dialed in the weber. Aside from a slightly rough idle, it would rev up nicely yesterday and last night until today, with about 60 miles of driving on the carburetor.

 

Background: carburetor was rebuilt by me, I believe this may be the one I stripped down and cleaned in the ultra sonic cleaner (I have a few so I'm not sure exactly)

Throttle position switch, anti-diesel, mixture solenoid, and choke all test fine with multimeter. Everything operational

New distributor cap and rotor (copper terminals, ALWAYS). Haven't put the new plugs or wires on yet

All vacuum lines hooked up properly as per Fastboatman's write-up

Accelerator pump operational

Fuel level in sight glass a tad below the dot (will adjust)

Mixture screw probably 4.5-5 turns out from seated

I do need to adjust the throttle position switch a bit, possibly the boost controlled deceleration device as well

Evap vacuum lines a bit rotted, will replace

AB valve not on, ports used are capped off, just got one from a hardbody today I will throw on

O2 sensor brand new factory OE Bosch

 

Any advice? Had no stumble until today, it seems it's on a fully warmed engine. It's not too bad, it's manageable and doesn't affect driving much at all.

[datzenmike]

39 minutes ago, A guy named Rick said:

Mixture screw probably 4.5-5 turns out from seated

 

 

There is no exact setting for this. On a hot engine, turn idle speed down so any changes are more noticeable. Turn idle mixture screw in till it stumbles then out till it stumbles. There's maybe a half turn or more where it idles smoothest and fastest. Set roughly in the middle. If idle speed improved turn back down. Repeat in and out, finding the middle position where idle is strongest as many times as needed till you cannot improve idle quality and idle speed is about 700. Warm idle mixture is now optimal.

[A guy named Rick]

I'll try that. I'm talking about if you jab the pedal at idle it's a split second stumble. Idle mixture of course can cause this. I'll inspect the accelerator pump as well.

[datzenmike]

A sudden transition to the primary (causing a sudden lean condition) is mostly covered by the accelerator pump that squirts raw fuel. The sudden opening of the primary lets too much air in too fast. Just look down the carburetor with engine off. Stab the throttle open and there should be a strong squirt of fuel evident.

 

If rebuilt there are two ball bearings (BBs) in the accelerator circuit. When the accelerator plunger travels downward one BB blocks fuel from being pushed back into the float chamber but is free to lift up and allow fuel in on the up swing. The other BB  allows fuel out into the primary but is also spring loaded and prevents air being sucked back into the accelerator pump on the up swing. Both BBs act as one way valves. If one BB was lost in the rebuild or previously lost this would seriously affect the pump action.

[A guy named Rick]

I'm pretty sure I have the spring, weight and bb in the internal side and I have the spring and bb in the external side. Had strong flow of fuel from the squirter. I remembered your wisdom when rebuilding it.

 

I had another carb from a junkyard with 180,000 miles on it and the squirter worked fine until I let it sit months without doing anything with it. There was still fuel in the carb when I got it! So my dumbass plopped it on the truck and it wasn't squirting. So I remembered the one I had rebuilt, which I was reluctant to use because I heard internal vacuum leaks last time I tried putting it on. You could hear it. Guess it was my base gaskets (california, so I have a total of 3 gaskets, the metal plate and the heater).

Edited April 23, 2023 by A guy named Rick

[A guy named Rick]

Just confirmed that the accelerator pump is fine however it is not producing a strong squirt like it was. Maybe run some cleaner through fuel system?? 🤔🤔🤷‍♂️🤷‍♂️

 

Edit: I also got the fuel level right at the dot now. Just need to finish smoothing the idle out, possibly adjust the BCDD, TPS, install the AB valve (had to fetch one from an 86 hardbody in the junkyard. Same part#), new plugs, then off to smog it. 

Edited April 24, 2023 by A guy named Rick

[A guy named Rick]

Would I be able to take the top off the carb while on the engine? Never tried, has anybody else? Then I could access the internal end of the accelerator pump system.

[datzenmike]

Sure can but the accelerator pump can be changed without taking it off. You can access the BB in the bottom but the other one on the output side you need the top off.

[A guy named Rick]

44 minutes ago, datzenmike said:

Sure can but the accelerator pump can be changed without taking it off. You can access the BB in the bottom but the other one on the output side you need the top off.

Precisely why I was wondering, because pump is good. I think it's internal. Makes no sense, I installed bb, weight, spring, screw cap. Was producing strong squirt, could even hear it! And now, nothing...

[A guy named Rick]

Instead of making a new post i will just add to this one. I have a dead alternator. Im sure it is because it goes like this:

Swapped on hitachi carb thursday, started having weak starting/barely starting the next day. Jump start worked when I needed it, dead right after getting home and trying to st

Battery was from Walmart, approaching 2 years, and I've been noticing mornings it almost doesn't start, like weak voltage to starter. Replaced battery Saturday. Issue returned again like Monday.

Tested starter yesterday, sparked inside the testing machine at autozone. Determined "your starter isn't good. Purchased rebuild from Napa. Keeping original to rebuild for spare.

Replaced it this morning. Battery at 1%. Jumped, drove, truck died out after 10 miles, some of it highway, around the corner from my house. Barely any lights, gauges, turn signals wouldn't work.

 

So definitely alternator. I'm cheap right now. I was thinking about sourcing a junkyard one until I rebuild mine as I need one by Monday morning no questions.

Edited April 28, 2023 by A guy named Rick
Typo

[bottomwatcher]

Got a meter?  Clean your connections real good especially the ground and plug in the back of the alternator. ( I know hard to do) but try the free things first. Then jump it and find out if it is putting out any charging voltage. Also I have had alternators drain the battery overnight although it charged fine when the engine was running.

[datzenmike]

OR.. Get running and briefly unplug one of the battery cables. If it's charging it will continue to run. If not charging it will quit. Don't run for any length of time with the battery disconnected just long enough to see what happens.

 

There are 3 fusible links two Green and a Black. The Black fusible link is what connects a charging alternator to the battery positive terminal. If it's blown it won't charge the battery back up when running even if working.

 

 

[banzai510(hainz)]

this would have worked alot faster

 

these work good.

 

Harbor frieight has a 6$ version also

https://www.amazon.com/INNOVA-3721-Battery-Charging-Monitor/dp/B000EVWDU0?th=1

 

most alternator from Autozone O rileys dont last more than 1.5 years if that.

Edited April 27, 2023 by banzai510(hainz)

[bottomwatcher]

10 hours ago, datzenmike said:

OR.. Get running and briefly unplug one of the battery cables. If it's charging it will continue to run. If not charging it will quit. Don't run for any length of time with the battery disconnected just long enough to see what happens.

 

 

 

 

This is old school redneck and can be hard on an alternators diodes. It is a simple process with a meter or the device banzai510 shows. Everyone who drives an old vehicle should have a least a cheap centek meter in the glovebox.

[A guy named Rick]

12 hours ago, datzenmike said:

OR.. Get running and briefly unplug one of the battery cables. If it's charging it will continue to run. If not charging it will quit. Don't run for any length of time with the battery disconnected just long enough to see what happens.

 

There are 3 fusible links two Green and a Black. The Black fusible link is what connects a charging alternator to the battery positive terminal. If it's blown it won't charge the battery back up when running even if working.

 

 

I've heard of the fusible links, probably seen them, but not sure what they are or how to check. Is there a fuse inside? Dumb question I know

 

When got a jump before buying a battery Saturday, the negative was loose and came off as he disconnected. Truck died immediately. So definitely was running on the battery.

 

I bought a junkyard alternator simply because the fact it was off a 99,000 mile truck AND it ended up being a reman. Unfortunately this was from an 86 hardbody so the plug is different. Instead of taking it back, can I just gut it out and rebuild mine with the parts? 🤷‍♂️ I need this truck up by Monday and I'm running out of options.

[datzenmike]

Go back and get the plug from the harness and swap it. They all changed around mid '80 to that larer plug.

 

 

This is my 100 amp 2002 Altima alternator and I swapped in the new plug

[A guy named Rick]

I'd have to check but it may be a situation like this:

 

 

[A guy named Rick]

Learned something today I can pass along to others. Well, in a pickle I need something now, so I'm kind of forced to buy aftermarket against the advice of you all. I will keep my core, give them my junkyard core, but to get the correct plug and not go cutting and splicing wires, I found out if you have a 1984-1986 720 with Z24 and you have the connecter style I have that looks like I- not the I I style, get an alternator for a 1983. Parts stores always screw you around with wrong stuff. For instance, my GF had a 2007 Versa (thankfully 4-speed auto and NOT a CVT) and I read some people were sold spark plugs that used a larger diameter socket that made it literally impossible to get down into the tube to bolt it in. Little things like that.

 

Wish me luck, I will be rebuilding my OEM and they can have my junkyard core that's already a rebuilt 🤣 and as for the $40.00 core, I'm making $6 after part and entrance fee 🤣🤣 The guy was also nice enough to let the OEM leather 5-speed shift knob slide by free 😉 and I got a negative grounded battery cable cheap as hell too.

[A guy named Rick]

It really comes down now to 50A or 60A. I have no AC, should I stay 50A or do I need to change any wiring to go 60A? Bigger is better, it's only a 10A different, that's where I'm stuck at for now. 

[datzenmike]

The 60 amp is optional and standard in colder countries like Canada. It simply recharges the battery faster after a cold start. Both alternators are the same just the output different. All things equal I would go with the higher output. My 710 comes with a 50 amp but I changed it to a newer 100amp alternator from a 2002 Altima. With headlights, fan and wiper on at idle there is no flickering of the lights at a stop with the turn signals on.

[A guy named Rick]

Alright going with the 60 amp. I hate being forced into this situation but with time and availability and ease, I have to go this route.

 

I need a new positive cable as well. They don't sell them like what I have, at least I can't find them anywhere. I have the terminal that's got 2 bolts clamping it to the cable so I can have the connector for the fusible link. It looks like I can either cut mine off, shortening it about 2 inches, or buy a cable and clamp separately and make my own.

[banzai510(hainz)]

29 minutes ago, A guy named Rick said:

I have the terminal that's got 2 bolts

those are junk and cause proplems.

Every part store has the norman leaded luged one bolt cables

 

50/60 dont matter if you dont have AC anyways. 50 should be fine but if 60 and looks the same then ok.

[A guy named Rick]

1 hour ago, banzai510(hainz) said:

those are junk and cause proplems.

Every part store has the norman leaded luged one bolt cables

 

Exactly... where would I clip on my fusible link harnes? Goes on a 3-blade connecter bolted on one of the clamps bolts...

 

[banzai510(hainz)]

I would put it at the starter lug so it hides it better than up top by the battery. Round lug

[datzenmike]

 

That's what I did with my 100 amp alternator. No way would this cable fit the battery clamp so I put a lug on the end and connected it to the starter lug. Put some harness covering on them to clean it up.

 

The one with the blue stripe came with the wrecking yard alternator and is bigger than the stock 710 battery cable beside it!!!