How to troubleshoot your TBI fuel injection system?

Troubleshooting your TBI Fuel Injection System Most of the problems encountered while installing your fuel injection system or after a time of operation are very simple. If your check engine light is on you more than likely have a hard fault meaning something is grounded out, unplugged, operating out of range or has gone bad. See

Is there an injector pulse while cranking the engine?

The engine will run if you either spray starting fluid down the throttle body or hook up a remote start switch. If you use the key, there is no injector pulse while cranking. As you let go of the key and return it to the run position, the injectors give one squirt.

What kind of scan tool do I need for GM TBI?

A scan tool can be used and set up for a GM TBI application to read the data, or to check for stored codes. Consult a service manual or see below for any check engine light code definitions. You can use a late 80’s or early 90’s GM TBI definition. If you have access to a scan tool use a hook up for a 1990 350 cu. in. 5.7L Chevrolet truck.

What kind of signal does a GM injector pulse have?

Purple/white wire with key on had barely any signal at all. Wires to the injectors have 12v with key on. I have fuel at the rear of the tbi but not sure of the pressure?

Where is the injector pulse on an ECM?

Okay ecm fires injectors with ground…should have a set of ground wires at thermostat..and one on intake behind where ac pump is or should be. Make sure clean and connected tight.

What kind of meter do I need for injector pulse?

I pulled the four pin connector from the dist. all I have is a standard radioshack volt meter. Purple/white wire with key on had barely any signal at all. Wires to the injectors have 12v with key on. I have fuel at the rear of the tbi but not sure of the pressure?

Can a fuel injector be rebuild, reconditioned or refurbished?

Can a Fuel Injector be Rebuild, Reconditioned or Refurbished? Almost all gasoline based fuel injectors are sealed units. The term: remanufactured , rebuild, reconditioned and or refurbished fuel injectors are misleading and a myth when it comes to fuel injector service .

How to test for fuel spray during crank?

This is to be an ignition 1 (ING1) source which is power in both the key run and crank position. Correct the connection of this wire and verify voltage to the pink wire on the injector connector. Test again for fuel spray during crank. If the engine still cranks, is spraying fuel, but will not start go to step 2.

What happens if the fuel injector is not working?

Fuel injectors are a vital part of a complex fuel management system. Furthermore, New technology has made fuel injectors more precise than ever in dispensing fuel. If the fuel injectors are not operating properly, then other parts of the engine will be affected as well.

Can a TBI be used as a return line?

These fittings are not suitable to use as a return line because they have an orifice in them and restrict the flow of fuel back to the tank. If you have installed your return line to a “vent” line you will need to route the return line in a different fashion. Fuel pressure on a TBI unit should stay constant under all throttle conditions.

What is the TBI code on a 1990 Chevy truck?

Consult a service manual or see below for any check engine light code definitions. You can use a late 80’s or early 90’s GM TBI definition. If you have access to a scan tool use a hook up for a 1990 350 cu. in. 5.7L Chevrolet truck. For some scan tools enter VIN 10th“L” 3rd“C” 8th“K”.

Why does my GM pickup engine not start?

How To Test The Fuel Pump On GM TBI Fuel Systems (for throttle body fuel injection fuel system equipped vehicles). A failure in one of the Passlock system’s components will cause the engine to start and then stall after a few seconds. This is due to the fact that the PCM, in your GM pickup or SUV, has disabled the fuel injectors.

Why is my fuel injection system plugged in?

The electric fuel pump installed for a fuel injection system will draw considerable more volume of fuel from your tank than your old system did. If there are any contaminants in the tank this many times will plug up or greatly restrict the flow of fuel to the system causing many issues. Step by Step Troubleshooting guide.

Is there no fuel from injectors to start truck?

No fuel from injectors to start truck. When I try and start my 93 Chevy Cheyenne k3500 no fuel come out of the injectors. If I use starting fluid the truck starts and the injectors work great. Has died a couple times while driving, but mostly runs fine and then won’t start one turned off.

What causes PCM to disable fuel injectors?

@jrt2020 , Josh, The anti-theft system (Pass Lock) failure will mimic this, as anti theft tells PCM to disable the fuel injectors.

Do you need Noid light for fuel injector?

All fuel injection and ignition functions are regulated by the computer control module, which is sometimes also referred to as the ECM, PCM or VCM. First of all you need a noid light to check for a pulse. A voltmeter will not work, neither will a 12 volt test light.

Why is there no fuel spray from injector?

On the way home it stopped and hasn’t run for weeks now. There is fuel and pressure at the injector but no spray. There is a red wire and blue wire there. The red has 12 volts, the blue is supposed to pulse on cranking. It does not pulse.

How to fix a 1990 Chevy 5.7L TBI fuel problem?

It ran long enough to drive up on the trailer while under its own power and it also drove off the trailer on its own power (not that same day I brought home) but you did have to keep foot on throttle otherwise it would stall out and not start again until the next day. 1. New Fuel pump 2. New Fuel filter 3. New Fuel pump relay 4.

How do you clean throttle body injectors?

Spray the injector or injectors with throttle body cleaner, and gently clean the exterior and the tip of the injector with the brush. Do not insert any metal objects into the tip of the injector, as this will enlarge the nozzle tip, permanently damaging the injector.

How does TBI work?

TBI fuel injection is a type of fuel injection system where the fuel is injected into the throttle body. The throttle body fuel injection system, or TBI as referred to by GM or CFI by Ford, works using a single or pair of injectors. The throttle looks like a carburetor without the fuel bowl, the metering jets or the float.

What is throttle body injector?

throttle-body injection. noun Automotive. a fuel-injection system in which an injector (throttle-body injector) delivers fuel to a central location within the intake manifold of the engine.

What is engine injector?

An injector is a device for introducing fuel under pressure into the combustion system of an engine. The vibration of the four-cylinder engine cracked a fuel injector pipe. Larger injectors increased fuel flow to the 2.4-liter turbocharged engine.

When to change the TBI pump in a car?

Nice thing about the Actron gauge is the hose is long enough that you can watch it while you drive. If the fuel pressure drops more than 1 psi under 8-10 seconds of full throttle the pump should be changed and dont put the stock TBI pump back in even if your engine is stock.

What should fuel pressure be on a TBI fuel injection system?

Fuel Pressure is critical to the operation of a fuel injection system. Always check to insure that you have the proper fuel pressure. Fuel pressure should be a constant 10 – 15 PSI on a TBI fuel injection system and is typically around 12 – 13 psi. Higher pressure than 15 psi indicates that there is an issue with the installation.

Why does my GMC Suburban no start flooding itself out?

If I unplug one of the injectors it starts up and idles and I am able to plug the injector back in and it will idle as normal. If I try and start it with both injectors plugged in, it just cranks and cranks without attempting to start.

What does it mean when there is no injector pulse?

In case of that, there is no injector pulse or spark, this means that is your ECU has failed in operating in this case you have to get your ECU changed or visit an expert. You May Like: Low Fuel Light Comes on When Tank Is Full Causes and How to solve it Question: What controls the fuel injector pulse?

Can a GM TBI be used for fuel injection?

TBI Fuel Injection Conversion using a GM TBI EFI system! One of the most popular EFI conversions to older Chevy engines or any engine for that matter is the GM TBI system using the 1227747 ECM. There are many others that will do the same thing but the 1227747 is most well known and documented and will be the basis for this article.

Why is my TBI fuel injection light on?

Why is there no pulse from the injector?

Used all original electronics and tbi. New wires, plugs, cap, rotor, fuel filter,etc… have spark, have fuel at the back of the tbi. No pulse at all from either injector?

What kind of EFI system do I need for a TBI engine?

TBI Fuel Injection Conversion using a GM TBI EFI system! One of the most popular EFI conversions to older Chevy engines or any engine for that matter is the GM TBI system using the 1227747 ECM.

Where does the vacuum leak come from on a TBI?

There are instances where the vacuum leak is coming from the adapter plate used to attach the throttle body to the manifold. If this is the case make sure that the seal is positive between the manifold and the adapter plate; also between the adapter plate and the throttle body.

What should the idle speed be on a GM TBI?

Insert a T-30 size Torx driver into the Idle adjustment screw that is located behind the plug removed earlier. Turn the screw to adjust the idle speed to 650 RPM +/- 50 RPM. Turn off the engine and disconnect the negative battery terminal from the battery using a wrench.

How do you change the idle speed on a T-30?

What happens when Spider fuel injector does not start?

One or two (at the most) cylinders are affected. This leads to a misfire condition and usually specific cylinder misfire trouble codes. The entire ‘Spider’ assembly stops injecting fuel. When this happens, the vehicle cranks but doesn’t start.

What causes a CPI fuel injector to fail?

The most common type of failure in the CPI ‘Spider’ fuel injector system is usually fuel leaks (inside the intake manifold plenum).

Where is the Maxi injector on a Chevy truck?

The MAXI injector is mounted in the center of the intake manifold on the 4.3L engine, and is hidden inside the split plenum manifold. Instead of spraying fuel directly into the manifold like a throttle-body injector, the MAXI injector routes fuel into six nylon fuel lines that have poppet-style spray nozzles on the end.

@jrt2020 , Josh, The anti-theft system (Pass Lock) failure will mimic this, as anti theft tells PCM to disable the fuel injectors.

Why is my 1991 Chevy 350 TBI stalling?

I changed the IAC, set the timing, new plugs, wires, and changed a ton of rotted vacuum hoses. The vehicle ran perfectly as long as it wasn’t idling. It idles extremely rough, and has been stalling. There is no tach, but it seems like it’s falling bellow 500 in drive and maybe sitting at 750ish in park.

Why does my TBI engine hesitate from the EGR opening?

One thing I do know that TBI engines do is hesitate from the EGR opening too soon. What you have to do it get a little vacume delay switch that goes in the vacume line before the EGR port and it can delay the opening for up to 1.5 sec.

How does a high pressure fuel injection system work?

Refer to the illustration below for the details. A leak off at the high pressure fuel pipe or ends from the annular space is led through a leak off line to an alarm pot or leak off tank and then to the fuel oil drain tank. Outer sheath of the pipe prevents spillage of leak off oil to the surroundings.

Do you need a tachometer for fuel injection?

Use of this section may require a digital voltmeter, test light, fuel pressure gauge, timing light, tachometer and/or a diagnostic scan tool. If you are familiar with vehicles and how they are serviced you should be able to work through this section with no issues.

How does a return style fuel system work?

Of course, the cornerstone of any good return-style fuel system is the fuel pressure regulator which maintains the necessary fuel pressure in the fuel rails, and sends the unused fuel back to the tank.

Who is the bad guy in the fuel system?

Their fuel systems have fed some of the world’s quickest race cars, and recently GM picked Aeromotive to supply the fuel systems for the new COPO Camaro. Fuel pumps always seem to be the bad guy when it comes to fuel system troubles, but the truth is that improper plumbing is at the root of many issues like vapor lock and cavitation.

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