5.8 Engine

[mmarincic]

I just bought a 1994 Four Winns with a 5.8 ford engine with fuel injection. When I took it out this last week the motor won't idle good. It keeps surging up and down from almost quitting to about 600 or 1000 RPM. The mechanic that installed this engine said that sometimes this engine will do this and that it is normal.
I don't think it should be normal and so I thought I would put it up for answers from the experts.

 

[fast50]

Re: 5.8 Engine

try cleaning the throttle body and the iac and check the sensor grounds ford cars and trucks had problems with ecm loosing internal grounds may be the same on boats .also check ect for rationality if it has one for the ecm

 

[QC]

Re: 5.8 Engine

I moved this over to the I/O and inboard forum. You'll get more help here. Engines are not specific to boat makes, so all we need are guys familiar with this setup in any boat to help out.

Good luck!!

 

[180shabah]

Re: 5.8 Engine

Time for a new mechanic - there is nothing normal about a surging idle.

Clean grounds and connections are always a good place to start.

Cleaning the throttle body and IAC, also a good suggestion.

As mentioned above, if this doesn't help, it is time to retrieve codes.

 

[danond]

Re: 5.8 Engine

Ford engine idle surging can be caused by a faulty TPS (throttle position sensor). You need someone to do a diagnostic for you and figure out why the computer can't figure out what the engine's doing.

 

[bruceb58]

Re: 5.8 Engine

try cleaning the throttle body and the iac and check the sensor grounds ford cars and trucks had problems with ecm loosing internal grounds may be the same on boats .also check ect for rationality if it has one for the ecm

I really doubt this is a throttle body. Is this an OMC by chance? You need to state what you have. More than likely, this has 8 seperate injectors.

 

[180shabah]

Re: 5.8 Engine

Even with MPI, it would still have a throttle body and IAC.

 

[fast50]

Re: 5.8 Engine

after the engine runs for awhile and reach operating temp does the idle smooth out

 

[fast50]

Re: 5.8 Engine

and if the engine was just installed i would check your sensor grounds that is a characteristic of fords when they loose there sensor ground

 

[a70eliminator]

Re: 5.8 Engine

Yep I agree there's just too many things effected, although the 5.8 in my car will do the idle hunting thing after winter storage, it's because the battery is disconnected and removed and upon start up the computer has to relearn baseline parameters then after run for a while it starightens out, don't know if this can be compared to the marine set-ups though?

 

[willieboy]

Re: 5.8 Engine

Sensor grounds or dirty IAC.

 

[mmarincic]

Re: 5.8 Engine

This is a OMC. The engine was rebuilt by Rocky Mountain Engines in Denver and has about 15 hours. It still surges even after being run and warmed up. I.am going to take it back to the guy that put it in , in the next couple of days. I just wanted to get your expert advise.

Thanks for your time and answers
Mike

 

[fast50]

Re: 5.8 Engine

well lets us know his findings