7.4 smoking??

[petea]

I have a 1997 7.4 mercruiser fuel injected.Lately when i first start it,It starts smoking alot. After it warms up it stops smoking. It runs great, no motor noise."ticking or knocking" I was told it could be the iac motor sticking??
Would that cause it to smoke when it first starts? And were is it located?

 

[Bondo]

Re: 7.4 smoking??

Would that cause it to smoke when it first starts?

Ayuh,... My 1st Guess would be Bad valve guides/ Bad valve seals...

I have No idea how a Bad AIC could cause start up Smoke...

 

[Don S]

Re: 7.4 smoking??

Could be an overly rich condition because of a failed sensor in the system telling the ECM to add more fuel.
THere are manuals up in the Adults only sticky at the top of this forum. It has details on checking them.

 

[SuperNova]

Re: 7.4 smoking??

Ayuh,... My 1st Guess would be Bad valve guides/ Bad valve seals.....

Could be an overly rich condition because of a failed sensor in the system telling the ECM to add more fuel.
.

Can you tell what color the smoke is? Whitish-blue or Grayish-black maybe?

 

[petea]

Re: 7.4 smoking??

Grayish-black and smells like fuel.

 

[Bondo]

Re: 7.4 smoking??

Grayish-black and smells like fuel.

Ayuh,... Once Again,... It sounds like Don is Right,...
And,..
I'm Not....

 

[Bronc Rider]

Re: 7.4 smoking??

You are going to have to check the sensors as Don suggests. If its beyond something you can handle find someone that has the correct diagnostic scanner (Merc service dept. is best). Once you find out what it is, you can take it from there. I'm pretty dull when it comes to electrical so I find it a wize investment to have Merc tell me whats wrong with it. I wont have them repair it but, I do have them tell me whats wrong with it.

BTW, bad IAC will cause poor idle like too high, too low or surging.

 

[petea]

Re: 7.4 smoking??

Thanks guys!!

 

[SuperNova]

Re: 7.4 smoking??

Yeah, don't think it's a bad IAC, but it could be the IAT or CTS, hopefully it doesn't take the FBI, CIA or NSA to figure it out before the EPA gets on you for bad MPG or HCE.