# Convert fuel injection to carb



## Douglas Gies (Jun 21, 2019)

How can a fuel injected. K24 be converted to carbs


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## rogoman (Dec 16, 2004)

The KA's never came with a carb setup. Here's what you have to do for a conversion to carbs:

1. The lower intake has to be changed for one with a place to mount a carburetor. In most cases a different manifold is required. You would have to customize a throttle linkage for the carb.
2. The fuel pressure for fuel injection is higher 40+psi, a low pressure fuel pump would have to be used and a fuel pressure regulator for carb level pressure of around 5psi. Is needed. The fuel rails or fuel lines need to be changed out at least for the last few feet.
3. The ignition system needs to no longer be computer controlled. That might mean an MSD style ignition box or just a coil and distributor swap.
4. The ECU would probably have to be eliminated; the rewiring could be a real mess.
Your ignition and computer are probably the hardest parts, getting the engine to fire up again might take some extra effort. Air, fuel and spark will all need some attention. 

I have to wonder why you would want to do that? That is, changing from a very efficient fuel system to one that isn’t. Take a hint from the car manufacturers, most new cars have Fuel Injected Engines. Fuel Injection when controlled by the millisecond precision of a computer gives 10x better performance and tighter feedback to the whole chain of input from the throttle pedal to the tires. If your reason for changing from EFI is because it is not working correctly, you would be far better off learning about your EFI system and then diagnosing and correcting it.


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## Douglas Gies (Jun 21, 2019)

rogoman said:


> The KA's never came with a carb setup. Here's what you have to do for a conversion to carbs:
> 
> 1. The lower intake has to be changed for one with a place to mount a carburetor. In most cases a different manifold is required. You would have to customize a throttle linkage for the carb.
> 2. The fuel pressure for fuel injection is higher 40+psi, a low pressure fuel pump would have to be used and a fuel pressure regulator for carb level pressure of around 5psi. Is needed. The fuel rails or fuel lines need to be changed out at least for the last few feet.
> ...


I have been fighting this problem for months! Have practically memorized the shop manual! Starts and fast idles as should, idles down in a few minutes then revs high, then continues to be very radical. I have set timing,replaced mass air sensor,idol air valve in throttle body, elimated cadiletic converter, replaced seals on injectors. About the only thing I haven’t done is check the operation of injectors by removing the distributor and rotating to observe their operations. HELP!


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## rogoman (Dec 16, 2004)

First of all describe your vehicle; year, model, engine - KA24E or KA24DE, tranny. Here are some suggested fixes:






FIX: erratic idle, low speed driveability, possibly more - Infamous Nissan - Hardbody / Frontier Forums


FIX: erratic idle, low speed driveability, possibly more Wiring and Electrical



www.infamousnissan.com





* - Intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.

* - Incorrect fuel pressure. Tee-in a temporary fuel pressure gauge at the output side of the fuel filter. The readings at idle should be around:

with vacuum hose connected to the fuel pressure regulator: 34 psi
with vacuum hose disconnected from the fuel pressure regulator: 43 psi

* - Dirty or leaking fuel injectors. Run some good injection cleaner, like Techron, Redline SL-1 or BG products 44K, through the system; give the cleaner about a week or two to do it's job.

You may have leaking fuel injectors. To test them, unbolt the fuel rail from the intake manifold and pull off the entire assembly. Keep the fuel hoses still connected and don't remove any individual injectors. Unplug the ignition coil wire from the coil. Also keep the electrical connectors on the injectors. With the assembly now away from the intake, turn the ignition key to the run position WITHOUT STARTING THE ENGINE. Now observe each injector to look for leaks. There should be no drips.

While you have the rail assembly still removed, place a heavy towel under the injectors. Now while holding the fuel rail up above the towel, have someone turn the ignition switch to START; observe the spray pattern of each injector while the engine is spinning.

* - Marginal EGR valve.

* - Marginal ignition coil.


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## Douglas Gies (Jun 21, 2019)

rogoman said:


> First of all describe your vehicle; year, model, engine - KA24E or KA24DE, tranny. Here are some suggested fixes:
> 
> 
> 
> ...


Wouldn’t spraying a wd40 at the manifold give me a air leak detection?


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## rogoman (Dec 16, 2004)

Either spraying WD40 or just a plain water spray mist will work. However using a vacuum gauge is a more precise way of measurement and using a vacuum gauge gives additional readings that help in troubleshooting:

Here are some vacuum gauge readings and their indications:
----------------------------------------------------------------------------------------------------------
Low & steady: Late ignition timing/valve timing, low compression

Very low: Vacuum leak

High & steady: Early ignition timing

Gradual drop in reading from idle to higher RPMs: Excessive back pressure in exhaust system

Intermittent fluctuation at idle: Ignition miss, sticking valve

Needle fluctuates as engine speed increases: Ignition miss, blown head gasket, leaking valve or weak valve spring

---------------------------------------------------------------------------------------------------------- 

The easiest test for converter plugging is done with a vacuum gauge. Connect the gauge to a source of strong intake vacuum on the intake manifold. Note the reading at idle, then raise and hold engine speed at 2,500 rpm. The needle will drop when you first open the throttle, but should then rise and stabilize. If the vacuum reading starts to drop, pressure may be backing up in the exhaust system.


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## rogoman (Dec 16, 2004)

SavayVosabi said:


> Why bother yourself if you can give it to a car service? Problems with finances? I also had this, I got to the casino maxi website, earned my 1 million. Since then, if the car breaks down, I immediately buy a new one.


Not everyone has a million dollars like you that they can run out and buy a new one. Many folks are on a tight budget. That's why they come here to the forum for some help. We all try to help each other. That's called "family".


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## Douglas Gies (Jun 21, 2019)

rogoman said:


> First of all describe your vehicle; year, model, engine - KA24E or KA24DE, tranny. Here are some suggested fixes:
> 
> 
> 
> ...


Attached gage to line going to the ear valve ,have only 10 or 12 reading. Sprayed water around intake ,get no change. Could there be a leak internally? Ka24,1994 pickup
Thanks


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## rogoman (Dec 16, 2004)

The ear valve? You mean the EGR valve? The hose at the EGR valve may not be at full vacuum depending on the activation of the EGR solenoid. The hose leading from the EGR solenoid to the intake manifold *IS* full vacuum. If your gauge is really connected to a full vacuum source, then a 10 or 12 reading usually indicates a major vacuum leak in the intake system. Check the intake manifold nuts to make sure they are tight. The gasket may have failed; also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps; if all that checks out OK, then there may be late ignition timing/incorrect valve timing, low compression.


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## Douglas Gies (Jun 21, 2019)

rogoman said:


> The ear valve? You mean the EGR valve? The hose at the EGR valve may not be at full vacuum depending on the activation of the EGR solenoid. The hose leading from the EGR solenoid to the intake manifold *IS* full vacuum. If your gauge is really connected to a full vacuum source, then a 10 or 12 reading usually indicates a major vacuum leak in the intake system. Check the intake manifold nuts to make sure they are tight. The gasket may have failed; also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps; if all that checks out OK, then there may be late ignition timing/incorrect valve timing, low compression.


Found a better vacuum source,hose to breake booster. Have good vacuum. Tested injectors and found #2 was dead, switched connectors and ther is no signal to #2. Will check wiring.


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## Douglas Gies (Jun 21, 2019)

Douglas Gies said:


> Found a better vacuum source,hose to breake booster. Have good vacuum. Tested injectors and found #2 was dead, switched connectors and ther is no signal to #2. Will check wiring.


I have checked voltage from ecm and to injectors. All test ok,13.7v. Now it runs a little better but can’t set idle with the throttle position sensor disconnected revs high. Double checked injectors, all are working, am running injector cleaner see what happens.


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## Douglas Gies (Jun 21, 2019)

See above


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## rogoman (Dec 16, 2004)

It's best to use a NOID light to test for a pulse at the signal wire for each injector. A multimeter is good for testing constant voltage.


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## Douglas Gies (Jun 21, 2019)

What is a NOID lite?


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## smj999smj (Jan 1, 2006)

Douglas Gies said:


> What is a NOID lite?


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## Johann van zyl (Jul 31, 2021)

rogoman said:


> The KA's never came with a carb setup. Here's what you have to do for a conversion to carbs:
> 
> 1. The lower intake has to be changed for one with a place to mount a carburetor. In most cases a different manifold is required. You would have to customize a throttle linkage for the carb.
> 2. The fuel pressure for fuel injection is higher 40+psi, a low pressure fuel pump would have to be used and a fuel pressure regulator for carb level pressure of around 5psi. Is needed. The fuel rails or fuel lines need to be changed out at least for the last few feet.
> ...


Once it get old after 150 k kms , its endless problems and it unreliable and you cant trust these midern engines. Even with OD 3 diagnostic tools, its still an hectic mission to get something gux and expensive. No go back to simple carburettor and distributor ignition. They were east to faultfind and cheap to fix for the DIY motorist lover.


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## ankyzop (5 mo ago)

distributor has no advance you will need the above distributor when switching to a carburetor. You will also need a new fuel delivery system (you can just install a pressure regulator or you can get a new low pressure pump). This is basically all you need to convert your factory fuel injection to carburetion.  techzpod download mobdro


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## dustidoodle (3 mo ago)

Any chance youknow which model of distributer for nissan I should be looking for? I need to convert my old KA24e


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