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Is it a bad iac valve?

Cap'n Crunch

Cap'n Crunch

New member
5.0L MPI , Alpha 1. Hard start cold or warm but especially cold and won't start when cold w/o throttle open about 1/4 (using neutral override button). Will not idle in low neutral (shift straight up) when cold, but will idle as it should when warm. Will start in neutral when warm but takes a couple of tries to fire up. From what I've read, this follows some of the symptoms of the IAC, but not all of them. Your thoughts are appreciated.
 
Hoping the IAC is the culprit. Talked to a mechanic and he said it might be the high pressure fuel pump and he said that's a nightmare to get at, under the engine. Why the heck would mercruiser put a fuel pump UNDER the engine?!
 
Cap'n Crunch said:
Hoping the IAC is the culprit. Talked to a mechanic and he said it might be the high pressure fuel pump and he said that's a nightmare to get at, under the engine. Why the heck would mercruiser put a fuel pump UNDER the engine?!
Click to expand...
It is actually easy to get to, Doubtful your pump is faulty.

Remove the IAC muffler and see if your condition gets better.

If not, change the IAC and install a new muffler.
 
Hi Chris, Thanks for the reply. I will take your advice but I'm not 100% sure where the muffler is located. If you can let me know, I'd appreciate it. Thanks again!
 
Number 6 on the picture assuming this is your engine.

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Ok, possibly located at the throttle body...that will be easy to check. If I don't see it, I can reply with the serial number. Thanks Chris, you have been very helpful!

Dave.
 
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