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Something happened to my injectors


skirkland1980

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I was making some dyno pulls on the 83 280zx turbo when the car died and hydro locked with fuel. It was running really well before this happened. I'm using the Bosch injectors found on Ford cfi engines. Static fuel pressure is 30 psi and multiplies with boost @ 25 psi. Anyone have an idea what happened to my injectors? Thanks

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It's more likely that something went wrong in the injector control circuitry. holding an injector or two or all open.  The injector's default condition is closed (spring), so unless you got some crap through the fuel filter and the injector filter, there's no reason for them to stick open.

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I wasn't thinking permanently stuck, I was thinking sticking open during running. If you were on the high side of the duty cycle, it could happen, but if you aren't pushing the injectors very hard it is unlikely.

 

If the engine flooded, either the fuel injectors dumped excess fuel, or the ignition source faltered.

 

The injectors stayed open too long from being pushed in the duty cycle, or something went wonky with the internals. 

Is the car running at all right now? What happens if you turn the fuel pump on, do any of the injectors just spray fuel? Were they new injectors?

 

How do you know it was hydrolocked with fuel?

 

If the ignition source faltered, you would have to find out if it was the coil, distributor, spark plug, or spark plug wire. If spark stopped being supplied you could potentially flood the motor a bit, although I would imagine the fuel would eventually make it out either by running down the side of the cylinder or exiting into the exhaust manifold or something of that nature.

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I only have answers to a few of your questions because it's been too cold to pull the fuel rail for inspection. I know t the engine hydrolocked because the starter just clicked. When I pulled all the plugs and soon the engine over fuel sprayed out in a 10 foot stream across the shop from at least 2 cylinders. I really need to get it apart and see what happened. Was just curious if this had happened to someone before and could either say yeah your injectors are fubar or not.

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Oh wow, that is quite a lot of fuel, yea, please don't crank that over. That can be an accident waiting to happen.

 

Were these new injectors? Where were they from? I know there have been some knockoff injectors sold under the bosch name as OEM replacements from certain aftermarket stores.

 

I agree, if possible test the injectors off the car. With ignition disabled. Me thinks you may find one or two of them on constant on. If it was enough to shoot out of the plug holes, you have quite a lot of fluid in there.

 

This is all with the assumption this is gas, I really don't mean to insult you, but there is no chance this is coolant or water correct?

 

I mean the last time I have seen fuel spray out of the sparkplug hole is with a flooded carb where the floats sank, but far more often, I have seen and heard of internally blown headgaskets flooding coolant into the chambers.

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Yea, it sounds like you are familiar with everything so it is hard to help out.

 

I guess to answer your question, yes I have heard of sticky injectors flooding motors, it could very well be the return spring or some fluctuating voltage or something of that nature. Even when injectors are remanufactured, they still don't inspect the internals, just a flow test and a rebuild with o-rings, maybe the filter screen is replaced to my understanding.

 

A bench test should be pretty revealing when it warms up enough to try it.

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Just FWIW, I'm 99.999% sure that a 440cc injector can't physically flow enough fuel to hydro-lock a running engine.  To me this would suggest looking for faults that would cause an injector or injectors to be open when the engine is _not_ rotating.  Sounds like you were already going down that path, just hadn't seen this explicitly pointed out.

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The engine backfired and died. When it backfired that is when the fuel started dumping into the cylinders. It was about a minute before I tried to crank the engine. It made about one revolution and stopped. So no I don't think it hydrolocked while it was running. That has happened to me before and it just bent the rod and kept running.

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You can  also check the injector outputs in tuner studio. Go to Advance then output test mode. It can be finicky but works. What are you using to trigger the megasquirt? Is the megasquirt reading RPM fine? Possibly something to look into also.if the case.   

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