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Reallyfastrider

1998 Malibu Sunsetter Problems

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Reallyfastrider

I have a1998 Sunsetter that will only fire when you put gas in TB. I have gas at injectors but they are not firing. I was wandering what tells the injectors to fire? I'm hoping that the ECM is good and something else is not telling the ECM to fire the injectors ie. ignition module or pickup coil. Any help in the right direction is greatly appreciated.

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Bozboat

What is the fuel pressure at key up?

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Reallyfastrider

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Reallyfastrider

I borrowed a fuel pump to make it wasn't that

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Bozboat

so, good fuel pressure at key up, spark because it fires when add fuel or carb spray to the throttle body?

but fuel injectors are not pulsing?

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Reallyfastrider

Yeah no pulse at injectors

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justgary

Do you have 12 volts at the red wires on the injectors?

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Reallyfastrider

Yes I have 12 volts on red wire

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Rednucleus

Don't know if this helps but when my 93 Suburban did this it was due to a failed ignition module located in the distributor. It ran fine with fuel added to the throttle body.

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Reallyfastrider

Is there a way to bench test ignition module?

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Rednucleus

No idea - my mechanic handled the problem - sub has 360k on it and am on the 3rd module. think he figured it out with a scan tool. Sorry, no idea how that relates to marine app. Not an expensive part to replace.

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Bozboat

Don't know if this helps but when my 93 Suburban did this it was due to a failed ignition module located in the distributor. It ran fine with fuel added to the throttle body.

When the ignition module fails you don't get spark. Is your kill switch working? Gauges move at key up? Edited by Bozboat

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Reallyfastrider

Thanks for the help guys, it was the ignition module.Boat is back on the water!!

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Bozboat

Thanks for the help guys, it was the ignition module.Boat is back on the water!!

That's great news. So a dead ignition module kills the pulse to the fuel injectors?

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Rednucleus

That's great news. So a dead ignition module kills the pulse to the fuel injectors?

It sure does in my 93 Suburban!! I love it when I make a lucky guess - a little bit of knowledge is a dangerous thing, but once in a while pays off, lol.

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justgary

That's great news. So a dead ignition module kills the pulse to the fuel injectors?

I suspect that the ECM has no way to synchronize the fuel without the reference pulse from the ignition module. In fact, without the reference pulse it doesn't even know that the crankshaft is turning.

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Bozboat

I suspect that the ECM has no way to synchronize the fuel without the reference pulse from the ignition module. In fact, without the reference pulse it doesn't even know that the crankshaft is turning.

I'm puzzled. Can you have spark with a dead ECM? Here the OP reports spark and the ability to run the engine by dumping gas down the intake. My no spark issue seemed to go away with a new ECM. I'm sure I don't understand exactly how all this works.

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justgary

I'm puzzled. Can you have spark with a dead ECM? Here the OP reports spark and the ability to run the engine by dumping gas down the intake. My no spark issue seemed to go away with a new ECM. I'm sure I don't understand exactly how all this works.

He didn't say he had a dead ECM, just a dead ignition module. My hypothication about the reference pulses may not be the exact problem, but I can see how the coil could continue to fire even when the ECM may not know when to fire the injectors.

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Bozboat

He didn't say he had a dead ECM, just a dead ignition module. My hypothication about the reference pulses may not be the exact problem, but I can see how the coil could continue to fire even when the ECM may not know when to fire the injectors.

A dead ignition control module not the ECM, right, I was confused. I still am not clear on what the ignition control module does

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electricjohn

I suspect that the ECM has no way to synchronize the fuel without the reference pulse from the ignition module. In fact, without the reference pulse it doesn't even know that the crankshaft is turning.

Absolutely correct. The reference pulse is the RPM input to the ECM. This and manifold vacuum (MAP input) determine pulse width of the injectors.

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electricjohn

A dead ignition control module not the ECM, right, I was confused. I still am not clear on what the ignition control module does

Mainly replaced the points and condenser of the 1960's, but also provides signal for reference and tach.

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