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| Symptoms of a bad IAC Valve? https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=9935 |
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| Author: | Technologic80 [ Fri Jul 27, 2012 8:47 am ] |
| Post subject: | Symptoms of a bad IAC Valve? |
I replaced my low pressure fuel pump on my 278 Vista (twin 4.3 TBI's). It was locked up and not pumping fuel. Go to start the boat this morning, as I always have trouble with the port side starting when cold. Sure enough, it started- albeit after 10 seconds or so of cranking and stalled right out. It never has started with the 'gusto' the starboard engine does. I.e. idling up on a cold start and nicely coming back down to idle. It always starts and goes right to 500rpms or so. Also, its really sooty on the transom by the port engine. Now Im thinking my IAC might be sticky/binding/bad. Does this sound like something a skewed IAC valve might do? |
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| Author: | neutron [ Fri Jul 27, 2012 1:59 pm ] |
| Post subject: | Re: Symptoms of a bad IAC Valve? |
The IAC acts like a choke on a fuel injected motor, it closes off the IAC port when cold and opens up as it warms up. should be open all the way after 10 min. usually they stick open and you have to crack the throttle to start the engine and keep it running till it is warm. not to say it cant stick closed or semi-closed making it run rich, just like a closed choke after warm easy to diag. after the engine is warmed uptake the IAC out and see what position the plunger is, if its causing your problem it will be out far instead of being retracted all the way. you can tell by looking how deep the plunger should go to close off the port in the hole. |
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| Author: | Paul I. [ Fri Jul 27, 2012 2:50 pm ] |
| Post subject: | Re: Symptoms of a bad IAC Valve? |
Very interesting! |
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