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Bogging and loss of power when hot outside and other problems.


lurkinheavy

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i have a 1989 bronco II 2.9l v6.
I has an issue where it will shudder and cut out and lose power over half throttle.
I replaced the spark plugs , wires cap and rotor,
and replaced the fuel filter , it still is shuddering and losing power , if i turn the key off and restart the engine it goes away for a while atleast 5 miles then will come back .
i tested my tps and got a vref volt of 4.95 signal volt of 1.11 at idle and at wot i received 4.62 volt so im assuming the tps is not the problem ,
im not sure if its the iacv or the o2 sensor or anything
i tried pulling codes by jumping the eec single wire plug to ground on the negative side of the batter terminal to count the light flashes only thing odd is the only light that shows up with the warning lamps is the battery light.
i also noticed with the key in the on position and engine off none of the warning lamps light up but the battery lamp i tried swapping the bulbs to see if it was a burnt out bulb but did not fix it.
so i have no way to identify or pull codes , is my ecm dead . i really have no idea whats going on and am really stumped anyone had to deal with anything like this before ?
 
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Uncle Gump

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I would check your fuel pressure and fuel pressure regulator for your loss of power issue.

I haven't committed wire schematics to memory... but I think the CEL is supplied constant 12v and is switched to ground by the ECM.

Do you have a service manual with electrical schematics?
 

alwaysFlOoReD

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Agree with uncle gump.
I'm not sure if the 89 has 1 hi-pressure in-tank pump or if it has the 2 pump system; low pressure in-tank and high-pressure frame rail pump. I've had problems with every frame rail pump where the connectors attach under the rubber boot. The connectors become loose and sometimes the pump doesn't work. Replacing the connectors with new has solved that problem for me. However it doesn't sound like you're having the pump cut right out. Fuel pressure is what it sounds like to me too.
 

lurkinheavy

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I have discovered interesting new info. i took it in to get diagnostic done and the fuel pressure was 35 psi and when they tried to pull codes the ecm was not communicating with the scanner. I then was like ok the ecm is dieing and thats what the mechanic thought too . well i replaced the ecm and nothing changed so i guess we can rule out the ecm being the issue . still dont see check engine light anytime i cycle my key and my gas gauge isnt working or my voltage or tachometer . anyone have any ideas why its running so poorly ? i heard the tfi can be a problem since it sends a signal to the ecu from the engine and im wondering if thats what went bad anyone able to confirm this?
 
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Nelson and Hudson

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It sounds like a fuel issue. Have you checked your fuel rail pressure while driving?
 

89Bronco2Micheal

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If the flex wheel is cracked could that cause loss of power?
 

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