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NEone smart enuf to figure this out??

Old 03-21-2007, 01:01 PM
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Join Date: Mar 2007
Location: United States
Posts: 4

It's been tuned. Here's the specs;;fuel injected, 4wd, 1991 isuzu amigo, 2.3, fuel line filter, the works. when i crank my car, it will not stay cranked unless i floor the accelerater and hear a slight pop. Once it's running it's fine until I stop at a store, then the same ole thing, a nice big push on the gas. And of course you all knowthat no one can afford to wastea gallon of gas upon startup.Any ideas?

Old 09-08-2007, 04:36 PM
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Join Date: Sep 2007
Location: United States
Posts: 16

Did you get it fixed yet?

Sounds to me that there is a problem with vapor lock (keep fuel lines away from high heat), or the pump's check valve is not holding residual fuel pressure. This will cause a hard start situation.

Try KOEO a few times, to prime the pump,If it starts then it's the fuel pump, or possibly injectors are leaking down. It would run rough on a cold start with bad injectors, then smooth out.

Gas is not being wasted, but your starting system is being over taxed.

(KOEO: Key On Engine Off)

Old 03-28-2008, 09:40 AM
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Join Date: Mar 2008
Location: United States
Posts: 8

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If it is a fuel injected motorthen the computer should be controlling the amount of fuel being delivered to the motor based on the throttle position, and a couple other sensors. When you depress the gas pedal you are actually giving the motor more air.

In order for the motor to run it has to have the correct balance of gas and air (as well as spark). It almost sounds to me like you have a fuel injector sticking open. When you turn the ignition on (before start) the fuel pump is pressurizing the fuel lines and injectors. If you have an injector sticking open then it will begin dumping fuel into the motor before the computer tells it to (before the motor is turning over). This means the the air/fuel mixture will be rich on fuel, so when you depress the gas pedal you are increasing the air part of the air/fuel mixture, making the mixture combustable again. If in fact a fuel injector is sticking open it will also leak fuel into the motor when you turn the truck off, because the fuel pump leaves the lines and injectors pressurized.

Carbon buildup can cause the injectors to stick open. Think of it as being a minature valve that cannot seat itself closed because of trash holding it open.

I don't know if your truck has an Idle Air Control (IAC) motor or not. It will be located @ the throttle body. It allows air to bypass the throttle body and enter the motor. Again, the computer controls this component. It restricts/allows air to flow into the motor in steps (retracts and extends a rubber plug). I do not think that this is your problem though, because you said the the motor runs fine once it is started.
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