unburnt fuel spewing from exhaust and flooding cylinders

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shawnathen
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Car: 1984 Nissan 200sx

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im putting a 89 ka24e in a 84 200sx right now and my problem is I think im getting way too much fuel in the cylinders , or left behind in the cylinders .
ive already changed injectors out so I know there not stuck open . maybe a valve is stuck and not allowing the piston to fire at idle ? if you rev the engine it wants to cut out like its flooding ,and like a said pure liquid gas sprays out of the tail pipe like a paint can . ive removed the valve cover and turned it , all valves appear to open and shut fully ??

any and all help would be appreciated greatly


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CSUPUEBLOTIM
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Do you have the vacuum hooked up on the fpr?

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pepesilvia
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CSUPUEBLOTIM wrote:Do you have the vacuum hooked up on the fpr?
yeah, the fuel pressure regulator would be my guess. its the only other thing that yur fuel depends on to flow at a certain rate other then the injectors or the pump. But the only difference is, even if yur pump somehow was pumping too much, the injectors would max out, but the FPR is supposed to catch it before it does that...

shawnathen
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Im not sure where the front 3 that come out by the powersteering.pumpgo

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CSUPUEBLOTIM
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Got a pic for us to look at?

N/A Q45
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CSUPUEBLOTIM wrote:Do you have the vacuum hooked up on the fpr?
100% chance that wouldn't cause that.

N/A Q45
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shawnathen wrote:im putting a 89 ka24e in a 84 200sx right now and my problem is I think im getting way too much fuel in the cylinders , or left behind in the cylinders .
ive already changed injectors out so I know there not stuck open . maybe a valve is stuck and not allowing the piston to fire at idle ? if you rev the engine it wants to cut out like its flooding ,and like a said pure liquid gas sprays out of the tail pipe like a paint can . ive removed the valve cover and turned it , all valves appear to open and shut fully ??

any and all help would be appreciated greatly

You more then likely have a bad ground to the maf or on the ecu itself. Had mine doing the exact same thing a few years back before I got into my build. You should check for codes and if you know how to check grounds with a ohm meter check the mafs ground at the maf and ecu, make sure to check both with key on and the key off.
Mine showed 100% grounded at the ecu with the key of, turned the key on and it lost almost all of its ground! So it's best to add extra ground wires to the shielding wires and the ground wires aswell. Good luck.

N/A Q45
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Oh yeah and try unplugging the maf while it is running. If it runs better with it unplugged then you have more then likely found the problem area.

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CSUPUEBLOTIM
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N/A Q45 wrote:
CSUPUEBLOTIM wrote:Do you have the vacuum hooked up on the fpr?
100% chance that wouldn't cause that.

With no vacuum hooked up the fuel pressure goes to pump pressure.

N/A Q45
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With no vacuum hooked up the fuel pressure goes to pump pressure.[/quote]

:wtf2:
And what's your point? It doesn't raise the pressure enough to cause what is happing- go pull your vacuum line, you probably won't even notice it run much different.

It can go to around 45psi. That's not the pumps max psi either.

shawnathen
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Car: 1984 Nissan 200sx

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ok all my lines are hooked up and the engine sounds really quiet ,but it still cuts out when your rev it up .
i dont have the exhaust return from the manifold hooked up or a maf . i just dont have one .
the car still runs rich though and has s*** coming out the tail pipe . head gasket ?

mechanicalmoron
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Why on earth would you think head gasket?

I figured your problem out:

You don't have a freaking mafs.

If you actually assemble the motor, maybe it will run right.

Maybe you should make friends with that guy who posted to ask why his CA with a leaking manifold gasket and no O2 sensor wouldn't keep boost up.

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PapaSmurf2k3
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This thread is riddled with misinformation.

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PapaSmurf2k3
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CSUPUEBLOTIM wrote:
With no vacuum hooked up the fuel pressure goes to pump pressure.
With no vacuum line hooked up, the fuel pressure goes to about 42-45psi, nowhere near enough to be spewing fuel from the exhaust unless of course the injector pulse is far too large.

With the vacuum hooked up, you get about 37-40psi of fuel pressure at idle.

Hell, pulling the vacuum would probably help him haha, he'd be sucking in a bunch of un-metered air that would help lean it out.
Then again, like MM said, it's unclear as to what the current setup is anyway. If there is no MAF hooked up, then yeah, that's a big freakin problem.

OP- does it only do this when you hit the throttle? Or is it running way too rich at idle too? Is there a MAF hooked up? Coolant temp sensor? TPS? We need more info here.

mechanicalmoron
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PapaSmurf2k3 wrote:This thread is riddled with misinformation.
To possibly add to that some:

And to totally put aside the fact that you need a mafs and such before you even think about this...

I think these would be top feed injectors, on a single cam? But if they're side feed, very rich/flooded states result from bad lower O-rings. When you replace injectors, you need to use a new ring, you need to be very careful to get all the pices of the old ring out, and you need to lubricate the new ring VERY well with vaseline or dielectric grease or some other clean light grease, or it will catch and tear on the way in.

By the way, check that you don't have gassy oil, or you'll ruin your motor before you get the problem fixed.

You could switch the injectors around to see if it moves the miss to another cylinder, telling you that it's a defective injector.
Last edited by mechanicalmoron on Mon Apr 29, 2013 8:47 am, edited 1 time in total.

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95zenki man
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I have been fighting the same problem on my 94 thunderbird. Dumping fuel out of the exhaust, skipping on 2-4 and just running like crap. I have never been able to find anyone else with a similar problem and while two completely different cars they might have a related problem?

Replaced
all 8 injectors
Fpr
Spark plugs and wires
Maf
Pcv
Coils

Hooked it up to a ford consult and the only code is intake gaskets. My buddy (ford master tech) said he really didn't think that would fix the problem ( it has been throwing that code for at least a year) im running out of things to change, please fill me in if you find the problem. Maybe ill get lucky and it will be the same.

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PapaSmurf2k3
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I think the injectors work by completing the ground cycle (normally via the ECU), but it you have an old wire that has rubbed through and is shorting out, then that could be sticking it wide open.

I always try tracing the wires/ohming them out/shaking them to see if the condition changes (especially on Nissans with their crappy OE harnesses).

You could also always pull the fuel rail (with injectors still in it), key on, and see exactly what is going on.

When it is running, you should be able to put a screwdriver to the injector, with the other end on your ear and hear them clicking/cycling. Compare the bad ones to the good ones.

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mattblancarte
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I'm just going to throw this out there, but you could find a Nissan mechanic near you to at least diagnose the issue... A legit mechanic could probably identify the issue within an hour or two.

There's a lot of brain power in this forum, but that probably won't get this issue solved.

Good luck! :mike

shawnathen
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I hooked up a maf and air box and it seems to rev just fine with out cutting out ,but starts running ruff after a few minutes .
im thnking I need to do a head gasket. ive done quite a few of them before just not one with a timing chain involved . any pointers?

mechanicalmoron
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shawnathen wrote:I hooked up a maf and air box and it seems to rev just fine with out cutting out ,but starts running ruff after a few minutes .
im thnking I need to do a head gasket. ive done quite a few of them before just not one with a timing chain involved . any pointers?
It. Is. Not. The. Head. Gasket.

Install everything properly according to FSM specifications, see that you have a good temp sensor, make sure the TPS is adjusted properly, make sure you have a good O2 sensor and that it's reading properly, make sure that your FPR is working properly, make sure that your timing is on and spark is strong enough, make sure that you're not throwing any codes. I don't know because I've never dealt with one, but I would think if all those are on, the CAS might be causing problems, and telling the injectors to fire at the wrong times, and/or causing spark timing issues.

Also, run it for a while, and get it hot - your cat is going to be a mess, and may cause backpressure related issues or poor running, but at least get all the crap burnt out that you can, take it for a spin.

To throw a gasket at what is clearly not a gasket problem is wishful thinking. If anything, you'll end up with a knick or imperfection or warp, that causes a bad gasket where none previously existed, in addition to the real problem.

shawnathen
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I have no cat . 3inch straight pipe . the longer it runs the worse it gets . it starts popping and throwing white smoke

mechanicalmoron
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shawnathen wrote:I have no cat . 3inch straight pipe . the longer it runs the worse it gets . it starts popping and throwing white smoke
Well check your oil and antifreeze. Is either dropping rapidly? Is either contaminated in an undue way? (bearing in mind that your oil will be very contaminated with gas, if you're flooding it)

If it runs really rich, the smoke will look white, if it's hardly burnt. At least, when I had a cylinder flooding, I had lots of white smoke, and my headgasket is just fine. Black smoke is where it's rich, but it's still burning, not like... liquid in your exhaust.

Maybe I'm totally wrong. I just can't see the gasket having anything to do with flooding out.

And if you mean the exhaust pops, even when things are running right your exhaust can pop on just a short rich period. OF COURSE it's going to pop if it's flooded, that's the unburnt fuel burning inefficiently and causing the smoke, smell, etc.

shawnathen
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water level seems fine ,oil smells like gas and exhaust burns white .burns a lot of gas also . I drove it hard up my street for all of 5 mins then it got rough , exhaust popping loss of power etc.
my exhaust manifold has no fuel return back to the intake ? is that major enough ?

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johnnyballs180
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i'm not going to pretend like I know what i'm talking about, but maybe your thermostat opens once warm and some coolant leaks into a cylinder. sounds dumb but white smoke is indicative of coolant. good luck!

mechanicalmoron
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shawnathen wrote:water level seems fine ,oil smells like gas and exhaust burns white .burns a lot of gas also . I drove it hard up my street for all of 5 mins then it got rough , exhaust popping loss of power etc.
my exhaust manifold has no fuel return back to the intake ? is that major enough ?
If neither looks all nasty, it's not mixed.

It sounds like a gas, ignition, or timing problem. To me, anyway.


And no, it has nothing to do with the thermostat, the thermostat doesn't let water into the block, it just throttles the flow to the radiator when the motor's cold. Heat can, I'm sure, cause warping and make a bad head gasket show itself, but something would happen to the water level.

shawnathen
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with a little tunning and taking the car for a spin it seems to be doing a lot better .

the exhaust still pops every now and then ,but it drives alright .

maybe a little rich still .

mechanicalmoron
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shawnathen wrote:with a little tunning and taking the car for a spin it seems to be doing a lot better .

the exhaust still pops every now and then ,but it drives alright .

maybe a little rich still .
NOT head gasket. :biggrin:

And, congrats. s12's look sick IMO, however primitive they may be.

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sancosys
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shawnathen wrote:I have no cat . 3inch straight pipe

Of course it will smell like and have unburnt fuel... Why arnt your running a cat? That 1/128 of HP is worth it? Install your cat.

I wouldn't know why anyone wouldn't run a cat. My car expels water vapor.

mechanicalmoron
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sancosys wrote:
shawnathen wrote:I have no cat . 3inch straight pipe

Of course it will smell like and have unburnt fuel... Why arnt your running a cat? That 1/128 of HP is worth it? Install your cat.

I wouldn't know why anyone wouldn't run a cat. My car expels water vapor.
It shouldn't smell like unburnt fuel, either way.

And it can pop, either way - though obviously, probably because something's not tuned quite right.


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