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Only startes with shot of either

 
  #1  
Old 06-12-2019, 09:39 AM
Jomama182
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Only startes with shot of either

I have a 1988 bronco, 5.0 efi, have tried replacing ect, iac, map, new cap and rotor, new high pressure fuel pump, throttle position sensor, ecu. Had local shop look at it, for 4 weeks, and they have no answer. Will turn over fine has spark and good fuel pressure but no start without quick shot of either into throttle body, then fires right up and runs perfectly. After starting and immediate shut down engine will not restart again without addition of either. Replaced starter with high torque starter just because, with no change. I am considering removing all efi components and replacing with carburetor and new intake.
 
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Old 06-12-2019, 11:39 AM
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If it's only starting with ether, but then running afterwards, then it's more than likely a fuel issue.
It sounds like fuel isn't being delivered during the starting phase. If it wasn't sparking during the START phase, then it wouldn't ignite the ether, either.

Disconnect the starter and then turn the key to the ON position, and check the voltage to the fuel pump. Then turn it to the START position, and be sure it's still getting voltage.
Same with injectors, etc.

You might have something wrong with the key switch itself, or some other wire, where the fuel system isn't getting fuel in the START position.
 
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Old 06-12-2019, 04:06 PM
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I can hear the fuel pump kick on when I turn the key, and the shop said it had good fuel pressure all the time, and it didn't bleed off when it sat between starts. Seems like a fuel issue to me also, because that little bit of ether is enough to make it start every time.
 
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Old 06-12-2019, 04:17 PM
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Yeah, if the fuel pump didn't come on when you turned on the key, it wouldn't run at all.
The ON position is what your engine is at when you're driving. So, if it runs and drives once started, then it looks like everything's working properly when it's in the ON position on the key.

The START position is different. There are several different circuits that shut off when the key is set to START to conserve power (such as head lights), and several others that turn on (such as your starter).

But if, for some reason, your fuel pump or your fuel injectors are getting shut off when you put your key in the START position, then even though the starter is turning over, and the spark plugs are sparking, there's no fuel going in. But, once you let off the key and it goes back to ON, then the fuel returns. If it's started at this point (such as with ether), it'll keep running.

So, it's possible you have a short (in the key switch or elsewhere) that's causing your fuel system to only stop working when the key is set to START.
This is why it'd be good to check the voltage at your fuel pump, and at the injectors, when the key is all the way in the START position, not just the ON position.
 
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Old 06-12-2019, 04:26 PM
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Would measuring the voltage at the fuel pump relay be the same as at the fuel pump itself, or should it be measured at the high pressure fuel pump on the frame rail. The relays have all been replaced also.
 
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Old 06-12-2019, 04:41 PM
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In this case, I would say the relay. Your fuel pump appears to be working, since you can drive it. If anything, it'd be the relay that's shutting off when it shouldn't be.
 
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Old 06-17-2019, 11:46 PM
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When you first turn to on there is a 5 or 10 second timer for the fuel pump then it waits for positive oil pressure to energies the pump for running. Check the sensor/switch for operation.

Ether is not your friend and will damage vital internals. It is used to start in extreme cold or engines with know issues.
 
 


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