'85 720 Z24 engine sputter. Need help !!

[MrRatty]

This is a 4cyl, with 8 plugs, so my knowledge is worthless.
It idles rough, and when flooring it in 2nd, 3rd, 4th, or 5th the engine sputters, and acts like its starving for fuel. If i back off the gas a bit, it seems ok.
Going up hills has the same affect. Under load fuel issues ??
What do you gurus think ?? gas line plugged ?, fuel pickup bad?
carb need rebuilding ?? stick of dynamite repair ??
Please help :confused:




BTW, I did replace plug wires, sanded plugs, cap, and rotor,
and replaced fuel filter. Im even using high test gas.

[BC Ace]

Did you replace the fuel filter by the tank?

[MrRatty]

Originally posted by BC Ace
Did you replace the fuel filter by the tank?

Yes, that is the one.
Although it took about 15 minutes to find. Hayes repair book, and owners book, doesnt show where it is.

[Hillclimber]

Its common for the wires to get switched up, my friend has a 720 and the wires were running from the coils to the wrong plugs... and the coils wernt working right. Check all wiring, then check the coils. The coils are both on when it warms up but goes to one after, so unplug one at a time and try it, then switch bacl ect.... also the stutter sounds like the timing is too far back or that the wires are cracked.
Long story short, the 720 has twice the crap of any other 4banger and is a Bi#ch to diagnose. Dont buy any parts till you diagnose everything or be prepared to pay $$$$ for wires, cap, coils ect... Dont asume that the last owner put the wires in the right order!!! Check that first.
Good luck.

[DopeyDog]

:flipoff2:Electronically Controlled Carb:flipoff2:

Dog
Currently working on getting EFI into his 84.

[MrRatty]

Originally posted by Hillclimber
Its common for the wires to get switched up,

Check all wiring, then check the coils. The coils are both on when it warms up but goes to one after, so unplug one at a time and try it, then switch bacl ect.... also the stutter sounds like the timing is too far back or that the wires are cracked.


I will check the plug wire order now. Thanx :)

I know the wires are not cracked, they are new.
I will get timing checked too. Thanx :)

[MrRatty]

Originally posted by DopeyDog
:flipoff2:Electronically Controlled Carb:flipoff2:

Umm, this WILL sound stupid, but how I even begin to fix it, or see whats wrong ???
Should i use my last option in first post ??"Stick of dynamite repair" ??

[BC Ace]

If you have the ECC, there will be a computer box under your passenger seat that you can get problem codes from.

[MrRatty]

Originally posted by BC Ace
If you have the ECC, there will be a computer box under your passenger seat that you can get problem codes from.
there is a box under the drivers seat, but i dont see any lights,.
I was told that i can watch the lights, and look it up to see what the problem is. But, No lights, No code !?

Any other help ?

[DopeyDog]

Well I didn't mean that personally just expressing my thoughts on Nissan's ECC. Please hold while I dig up diagnosis info . . . Do you got a Hayne's or Chilton's manual. . .

Diagnostic Procedure for Carburetor Engines
1. Inspect engine for air leaks, etc. (Vacum Lines, lots of em)
2. Check fuel supply system.
3. Perform ignition oscilloscope check. (Cap, Rotor, Coils, etc)
4. Check engine cmopression pressure.()
5. Check deceleration devices.
6. Check ignition timing and idle RPM.
7. Check idle CO%.
8. Perform driveability check.
9. Check detonation control system.
10. Check carburetor. (Check E.C.C. if you have it, CA)


And I can't find any information on trouble codes in the FSM, but have a nagging thought that I saw trouble codes for these things somewhere. Lights might not be in an easy to see location and I know it has lights at least one to indicate it's still working.

Dog
Good Luck with that.

[RussFEST]

Hey,

I recently had exactly the same probs on my 84 kingcab. But it is an 84 so I dont know if this helps but...

I changed the two filters by the tank. Theres the small inline one and then theres another one inside the electric fuel pump thats right beside the inline one. You have to get the filter from the dealer. I couldnt find an aftermarket one like the fram one I used to change the inline one.

I ended up taking off the carb and rebuilding it as well. That made a world of difference. It took me two days and picture taking as I took the thing apart as I am not the best at following exploded diagrams like the one provided with the carb rebuild kit.

On the top of the float bowl and indicator glass in the front theres the fuel line going in, remove the lock piece and take that banjo fitting line off. Underneath it there is another small screen filter. Check that, if its completely gummed wiht crap Id think about trying to flush your tank and/or rebuild your carb. Try using the carb cleaner stuff if after you change the filters it runs better.

When I ended up taking my carb off I found small crusted buildup from years in the float bowl of not adding the in fuel tank cleaners and also the jets were half plugged. The other advise I have is to take a can of something like WD-40 and with the engine running spray around the bottom and where the linkages go into the carb. That will tell you if you have leaks.

If you have some corrosion inside your carb that means that you have some water in your fuel tank. Make sure soon after you put Methyl Hydrate into the tank to eliminate the water. Also, (I did this), make sure when you change things like the accelerator pump on your carb that you put the spring the right way in. Theres a ball at the bottom and if you dont put the spring with the piece that is across the bottom of the spring down against the ball, the ball will not stay in the groove when you accelerate and it will affect your running.

Good luck and make sure you let us know what the problem turns out to be.

Russ

[MrRatty]

Originally posted by RussFEST
Hey,

I recently had exactly the same probs on my 84 kingcab. But it is an 84 so I dont know if this helps but...



I appreciate your thoughts , and what you did to your truck.
I will definitley look into the items you mentioned.
I'm thinking it may be better to swap it out, and get a V6.

Again, thanks for the info. I will post what happens


P.S. Hey Dopey, no offense taken. I know that anything in a car that is computer controlled is junk :mad: Except maybe the stereo:p

[MrRatty]

UPDATE


In the past 2 days, I have replaced the spark plugs, air filter, breather filter, used an entire 16 oz can of carb cleaner, and had the catalaytic converter replaced. :mad2:

I got a little power back, But, I still have the sputtering problem.

I am at my end, the dynamite idea is getter closer. Or at least a large cliff!:skull:

[DopeyDog]

The cat wouldn't cause sputtering, if you have over 100,000 miles on the current carb build then it probably needs a rebuild. I've been told the Nissan carb's have a bad habit of needing rebuilds every 100,000 or so. Unless you have the time and the patience (I tried rebuilding mine using the diagrams available, FSM and Carb Kit manual, ended up junking it) have someone do it or find a different engine. I've read buick's fit quite nicely, and ford's are nice too since they put the distributor on the front. Check out http://www.4x4parts.com for some ideas.

Dog
not that they are the only source for parts.

[LilRocky]

Could be a lot of things.. The 'puter cuts out one set of plugs when the engine's under load, so it could be a problem in the system that remains in use.
Things I'd check would include testing the coils and checking the cap/rotor for carbon tracks or burned areas. If there's tracking the spark can jump to ground or a non-firing cylinder when it's under load. Also, it's not uncommon for rotors to burn through and short to ground via the distributor shaft.
Check the sight glass in the fuel bowl to be sure the level's correct.
Also, checking primary wires to the coils is a good idea.. I've found similar problems caused by a loose connection in a coil primary.

Lots of other places to look, but I'd start with these...

And unless your engine is bad, there is absolutely no need to replace it. Engine repalcement due to inability to diagnose a problem is just a BIT of overkill...

[MrRatty]

Originally posted by LilRocky
Engine repalcement due to inability to diagnose a problem is just a BIT of overkill...

I whole-heartedly agree, but spending cash on replacing every other item on the motor, is the same overkill.

I am just frustrated that i can not find the problem.:mad:

Thanks for the info. I will look into it.:)

[LilRocky]

I am definitely NOT advocating replacing parts as a method of determining the cause of a problem. In fact I adamantly admonish people against "throwing parts at a problem" at any opportunity I get!

This looks like an opportunity, now!

Don't just throw parts at it! Do some careful and methodical diagnosis.

Start w/ the items I mentioned, and go from there.

Frustration will not help you find the problem, so relax. (Serious... No joke... Working in a frustrated state of mind is usually a detriment to good results, and often the cause of further problems!) Relax, take it easy, if you find yourself frustrated, take a break, or leave it until the next day.
You 'll be more efficient, both physically and mentally.

[MrRatty]

i replaced both the cap and rotor, and it does run better.
But, It still bogs when pedal is floored. I dont have the time to check the fuel system, so I will just have to live with this until i can find more time.
I'm going on a trip this weekend, and I hope it makes it.

Thanks to all for your input. I do appreciate it
:)

[MrRatty]

[QUOTE]Originally posted by DopeyDog
[B]:flipoff2:Electronically Controlled Carb:flipoff2:

Give that man a Ciiiiiiiigaaar !!!!!!:D

I just recently pulled the plugs on the ECC, and lo and behold my truck ran fine.:flipoff2:

It wouldnt idle worth beans, so i plugged one set of wires back in, and now my truck runs normal again:D

It will take awhile to find another ecc, but i will sometime

I want to thank you all for the input, I really do appreciate it alot.
Here's to you all :beer: :beer: :beer:

[Bare Performance]

Hey guys-

Glad I found this thread. It was the reason mine was sputtering and ran like crap.

Who would have thought that an internal filter in the fuel pump would have been the problem.

I tested this therory our by taking the filter out and putting it back together and it ran great. I wanted to put the filter back in because I didn't want to have to replace the pump down the road.

I had a rough time getting the filters so I ordered 5 of them for anyone else that might need one.

PM me or email me if you would like one shipped to your door.
Thanks
Ty

[radarwarrior]

Well, it seems that this is a common issue. I have a 1985 720 that spits, farts and sputter around the track. I know it is flooding coming out of the corners. Some say turn the carb around, but that is a machining issue. I do not have the ECU as all those systems were stripped by the previous owner. So what I am not clear on is, do both coils ust keep working as the ECU is gone? How much difference is there or would there be if I only used 4 of the 8 plugs? Does anyone have a suggestion for a older model Nissan carb that would work with less bumps in the system as I race around the track?

[toyotaforlife]

i have a 2bbl weber on my truck and i am having the same problems. do i need to disconect the ECC box or whatever? i just replaced all 8 plugs and i ran some fuel treatment through the gas. what should i do?

[NissanTiger]

Spark plug bank switching is controlled by the distributor module, not by the ECU itself. On the app with a weber, if you've disconnected the ECC, you basically disconnected the ECU. The ECU just monitors multiple vacuum switches, engine temp, O2 sensor, engine RPM and adjust A/F ratio via a valve in the ECC. Once you put on a Weber, you don't need any of that anymore. Sputtering at WOT, most like a fuel issue, not plugs. Dual plugs fire only at around idle to improve emmissions. Check your filters (and the one in the fuel pump), float levels, fuel pressure, main jetting.

For the stock carb app, there aren't any trouble codes for these ECUs, just check that the LED is blinking when the engine is warmed up and idling. These a pre-OBD ECU's, very primative with no trouble codes. Sputtering at WOT on a stock carb could be any of the above or wiring problems on the carb harness (common problem). Also, vacuum leaks can cause the same problem.

For more info on 720 stock carbs and ECC troubleshooting go here

http://groups.msn.com/NissanDatsun720PickupOwners/techtips.msnw

www.teamtigerracing.com

[toyotaforlife]

So do i need to clean my carb too, rebuild it or what? i will go to the parts store and get those filters and hope they work, and sence i have a weber on it can i unplug my ECU?... and witch seat is the ECU under? there is a small box under my passenger seat what does that do? it clicks whenever i hook up the battery and im thinking is causing my battery to die...:confused:...

yeah im a noob:flipoff2:

(Dennis)

[NissanTiger]

The ECU is under the drivers seat...

I'd say you could yank it except for one thing... there's a fuel pump control module that interfaces with it. Let me check the schematic on that before saying yes. Or, you can check it the old redneck way, yank it and see... (worst that could happen is the engine dies) I have Mikunis on my truck, I yanked my ECU but I wired my coils to fire both banks at all times..

If you go to the same link I referenced above, there's a test procedure for the fuel pump module, shows how to bypass it... I think you get the picture.

I don't recall anything under the passenger seat, sure it's not something someone added?

have you checked your fuel pressure at the carb? New weber carb, used carb??? Did it always sputter? Did you change anything before it started sputtering? Yeah I have a lot of questions too...

[toyotaforlife]

im not sure whether it was new when it was put on or used. and yes it has allways sputtered. im thinking sence im only running a glasspack muffler i dont think im gettine enough packpressure or something what do you think? and ill test that box the old redneck way.. thats the way i roll.:flipoff2:

-Dennis-

[NissanTiger]

I think the problem you are having is directly related to...

YOUR USER NAME...:flipoff2:

But, since you obviously came to your senses and got a Nissan, I'll let that pass...

Lack of back pressure isn't going to cause sputtering. I run my race truck with an open header, backpressure will only affect where your torque peak is.

If this is only happening at full throttle, I think you're either low on fuel pressure, or you need to increase the size of your main fuel jetting.

If you're sputtering all the time, you may be running rich. The first thing you need to determine is which, rich or lean. Check your plugs and see if they're black (but not oily). They should be ltan/ight brown if you're running close to 14:1 ratio which is about ideal.

Go here for good pics for plug reading http://http://www.theultralightplace.com/sparkplugs.htm

Are you running the right plugs? These engines will run on any common replacement plugs, but they really like the OEM NGK plugs the best, they are the right temp range for each side. Whereas common aftermarket plugs often use the same plugs on both the intake and exhaust. I don't recommend them.

[toyotaforlife]

well im runnin some Autolite plugs. the only reason i have a Nissan is cause when i was 15 i had a Toyota. my brother blew the motor and i sold the truck cause my dad needed something to drive. i really wish i didnt have a Nissan tho. it has broken too much sence i have had it. i ran it once. and i broke it. its a POS.. someday im going back to Toyota.

Thanks for the help man -Dennis-

[nissanrondo]

Having owned 2 720s, as well as my father owning 2 and my cousin one, let me chime in with our experiences. If any air gets in around the base of the carb, that will cause this. Also check every vacuum hose. Nissans from 1980-early 86 were notorious for vacuum leaks. Replace any hose that is suspect.

I've also tried every suggestion on this thread short of rebuiding the factory Nissan carb. I reached a point with my '85 that when i finally got it to stop idling rough and farting all the time, it would run good; but die periodically for no reason at all.

I got used to it :D

[toyotaforlife]

Ill just sell my Nissan and buy a Toyota then :smokin: :p :flipoff2:

[nissannut]

Sounds like the fuel pump control relay is acting up. Its under the dash by the glove box. Its next to the inhibitor realy if an auto. Its a 3"x2" box. When they fail they cause the fuel pump to turn on and off while driving.

The ECU can turn off the fuel pump if the oil pressure is low.

Use NGK plugs and OEM wires and You will have no issues. The plug wires are clearly labeled where they go. The OEM caps are labeled.

The stock carbs are famous for vacumn leaks. But thats usually just causes wierd idle changes.

[NissanTiger]

I'll give ya $100 bucks for your 720, as is...

But I wouldn't sell it if I were you. Especially to buy a Toyota!:rolleyes:

:grinpimp:

Is this a manual? With a weber carb on this it should be easy to figure out. Did you check your plugs? Do you have the right carb adapter on the manifold? Did you check your fuel pressure?

What you need is basic diagnostics... Anyone close by that can help you out? Where do you live?

Hope you figure it out man...

[toyotaforlife]

well you can buy my 720 Carb for 100$ and the rest of it for 1400$...


i did check my plugs and they were shitty. so i just replaced them with the cheepest thing i could find. im only 16 so money is in short supply. it is a 5 speed, and i didnt put the carb on so i dont know if i have the right adapter plate. i did not check my fuel pressuer, what should it be running at? ill just install a psi gauge in my dash so i can monitor it, (i was gonna do it anyways, this just gives me a reason)

And Nissannut, ill check out that fuel pump relay. and change my oil, does anyone know what type of oil is best for this motor? or how much oil pressure it should be at?...


i never had these problems with my Toyota:D


-Dennis-

[Purgatory]

Yeah I have the same problem as the original poster. I have a 02 Mustang V6. I have been doing modifications to the engine and here recently a "sputtering/hitching/bucking" problem started occuring. When ever I accelerate(esspecially a hard acceleration) the engine would begin to sputter -or what I affectionatly call 'coughing'- It sounded like the engine was starved for gas and about to die but simutaneously sounded as though it was getting too much gas and was about to flood out. Picture the sound of someone gargling or some porn star giving a really deep and sloppy...nevermind, just stick to the gargling analogy. The problem also occurs when I corner sharply while still on the gas. For a limited time I upgraded from regular to premium. I changed the fuel filter -which was dirty but didn't solve the problem- I also have a helix tower and cold air intake installed, so I'm ruling out fuel/air ratio problems. I will try cleaning the coils and see if that eliminates the problem and post back.

[themechanic]

Yeah I have the same problem as the original poster. I have a 02 Mustang V6. I have been doing modifications to the engine and here recently a "sputtering/hitching/bucking" problem started occuring. When ever I accelerate(esspecially a hard acceleration) the engine would begin to sputter -or what I affectionatly call 'coughing'- It sounded like the engine was starved for gas and about to die but simutaneously sounded as though it was getting too much gas and was about to flood out. Picture the sound of someone gargling or some porn star giving a really deep and sloppy...nevermind, just stick to the gargling analogy. The problem also occurs when I corner sharply while still on the gas. For a limited time I upgraded from regular to premium. I changed the fuel filter -which was dirty but didn't solve the problem- I also have a helix tower and cold air intake installed, so I'm ruling out fuel/air ratio problems. I will try cleaning the coils and see if that eliminates the problem and post back.

is the check engine light on??? might have a bad injector or possibily an intermintent plug wire arcking against the header

[nissanskickass]

i replaced my fuel filter and it ran like shit ended up that the filter inside had broken and was bouncing around in the lil plastick thing also ran like shit because i forgot to plug in one vacume line push it on and it purred

[Purgatory]

is the check engine light on??? might have a bad injector or possibily an intermintent plug wire arcking against the header

Yes as a matter of fact the check engine light is on. I looked at plugs and connectors yesterday in the midst of another Arkansas heatwave. After leaning over the fender of my car and receiveing 3rd degree burns across my stomach I noticed the plugs looked marginally grimey but they appeared to hold their integrity. Although I pride myself on my 'shade tree mechanic' skills I am at ends as to what's going on here. I also noticed no grounding of the cables but I will take a closer inspection. Bad injector sounds plausible. (please God no!) I have have dumped tons of fuel injection cleaner into my tank in the past couple of months so I would assume the injectors are not dirty. /sigh *places gun in mouth, contemplates...*