93' OMC Cobra 5.8 - runs rough

[pstill]

Hi! I've looked through the post and can't seem to find my answer. At idle engine seems to do fine but acts like it lopes a little. When I accelerate under load it will not go over 2500 rpms and shakes violently. I have changed fuel filter, fuel pump at fuel filter, fuel pressure is 37 psi. I have also changed distributor cap and rotor arm. I am running on an external fuel tank with fresh fuel because there is water in fuel tank. Any help would be appreciated, been working on this a while. Thanks!! Phil

 

[Bondo]

Re: 93' OMC Cobra 5.8 - runs rough

fuel pressure is 37 psi.

Ayuh,... Is this a fuelie motor, or Carbed,..??

Carbed motors run 5psi fuel pressure...

 

[JustJason]

Re: 93' OMC Cobra 5.8 - runs rough

Carbed or injected....

If you have water in your carb.... Its not comming out by running the engine

If you got water in your injectors... you could have ruined them

2500rpm is also a majic number for a guardian/warning system to kick in and limit rpms... any alarms? Do your alarms actually work?

How `bout a model/serial ## for your engine so we know what were working with.

 

[pstill]

Re: 93' OMC Cobra 5.8 - runs rough

Thanks for replying guys.

Engine is fuel injected. S# T0126835 OID# 58FAPRJUN
No alarms sound. In neutral can rev up 5500 to 6000 rpm it's only when in gear that it wants to act up. I pulled lower unit and checked the drive shaft and universal joints,and prop shaft, all looks real good there.

Thanks
Phil

 

[pstill]

Re: 93' OMC Cobra 5.8 - runs rough

Thanks, appreciate the help. Will test tonight.

 

[pstill]

Re: 93' OMC Cobra 5.8 - runs rough

Thanks, appreciate the help and info. Will get on it tonight. Will reply with results.

 

[airdvr1227]

Re: 93' OMC Cobra 5.8 - runs rough

In neutral can rev up 5500 to 6000 rpm

Sounds awful high for the 5.8L . WOT on mine is 4500 +/-