can't go above 2700 RPM without engine spuddering

ballworth

Recruit
Joined
Sep 18, 2004
Messages
4
I have a 1993 Seaswirl 21 ft Striper with OMC Cobra Ford 5.0L EFI motor. In or out of water (with muffs on) you can increase power to 2700 RPM. After you reach this magical number the motor acts like it is goverened. Cuts in and out. Misses or surges. If you decrease throttle back to 2700 RPM works fine. Motor has run good up till now. Started to happen after a 2.5 hour run. If you stay below 2700 RPM runs good. Changed feul filters and verified no water in feul by pumping a gallon into a gallon glass jar and letting it sit. No water in feul! Had to return to base camp over open waters and rough seas barely on a plane. The normal 2.5 hour trip took 4 hours at slower speed. Anybody have any ideas?
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: can't go above 2700 RPM without engine spuddering

i don not no your motor but with efi in general after you have changed the filters the only easy thing you can go is check the timeing and see if it is geting full advance<br /><br />i assume your cap rotar and plugs are recent<br /><br />the bad thing with efi is you need to know what the ECM thinks is going on in the motor which requires the correct tools not at all user friendly<br /><br />fuel pressure guage<br />code reader<br />service manual<br /><br />tommays
 

steve n carol

Chief Petty Officer
Joined
May 8, 2004
Messages
459
Re: can't go above 2700 RPM without engine spuddering

I realize that these are different engine configurations, however, the principals are much the same. read this thread, if you haven't already, and gleen from the frusteration and expense of the owner and gleen from the wisidom of those who have assisted this individual...sl<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=24;t=004947
 

ballworth

Recruit
Joined
Sep 18, 2004
Messages
4
Re: can't go above 2700 RPM without engine spuddering

Yes, Tommays, I think you hit the nail on the head with your statement "EFI is not user friendly".<br />Replaced cap and rotor. Checked out other thread mentioned. Will be doing compression checks later.<br />With An EFI motor (espicially the FORD 5.0L) doesn't the computer control the advance? Are there any circuits that might "govern" the engine? Maybe over temp?<br />Are there any good manuals? Seloc doesn't cover the Ford 5.0L with EFI.
 
Joined
Sep 18, 2004
Messages
8
Re: can't go above 2700 RPM without engine spuddering

The engine is going into SLOW mode it thinks it has overheated or has no oil pressure. You need to check your over heat sensor and low pressure switch to see if they went bad. The best way to check them is to disconnect them and try the boat. The overheat sensor is mounted in the intake manifold on the starboard side with a green wire going to it. The oil pressure switch is near the oil pressure sender for the gauge and it has a green wire going to it also.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: can't go above 2700 RPM without engine spuddering

I'ts not going into SLOW mode, that would bring down the rpm to 1200, not 2700 rpm.<br />Is the engine running smooth or does it have a miss.<br />It could be any number of the sensors causing the problem, or even the fuel pressure regulator or even a couple bad injectors.
 

ballworth

Recruit
Joined
Sep 18, 2004
Messages
4
Re: can't go above 2700 RPM without engine spuddering

Runs great below 2700 RPM. No miss, sounds good. On the water at 2700 RPM it holds speed (all though very slow) and seems to be ok. You can bring the throttle up 2700 with no problems. But once you go to 2710 it starts to cut out. Bring it back down to 2700 and it steadies out. Very consistent and predictable. Ran it at night in blackout condition too see if there was any arcing between wires. None!
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: can't go above 2700 RPM without engine spuddering

i have seen people fix EFI on this site on there own but every bodys system is diferent you have to have the OMC manual for your motor or you have no chance<br /><br />the posts i saw here the user had narrowed the problem down to a fuel pressure problem and useing a fuel pressue guage and the manual was able correct the pressure problem because it did not not invole the ECM<br /><br />that really is the only one i have read that was done with out being able to read the codes and he seamed to be a really skiled DIY person<br /><br />i build and repiar land based controls in the plant i run that are as or more complex than a ECM and with out the abilty to read a wireing diagram and hook up to a computer to see what is going on i might as well not even open the cover <br /><br />tommays
 
Joined
Sep 18, 2004
Messages
8
Re: can't go above 2700 RPM without engine spuddering

Don S. the Ford service manual for that engine states:<br /> "the engine will run rough, and engine speed will drop to 2700 rpm. below 2700 rpm the engine will run normally , but not above." It is a quote from the manual from ford power products on page 2a-10 so i think it is more likly it is going into slow mode and not a injector problem. But i was wrong on the color of wire it is actually tan/black. Also you can check to see if you have 12 volts at the post when the engine is running. 12 volts means the switches are ok, no volts mean bad switch in system.
 

marinemech

Petty Officer 1st Class
Joined
Aug 12, 2004
Messages
250
Re: can't go above 2700 RPM without engine spuddering

definitly going into slow as above oil pressure or water temp sensors or possibly ecu thinking the moter is hot or has low oil pressure what is engine temp and oil pressure?
 

ballworth

Recruit
Joined
Sep 18, 2004
Messages
4
Re: can't go above 2700 RPM without engine spuddering

Engine temp as indicated on gauge is about 150 degrees, oil pressure indicates between 40 (idle) and 50 (above idle).<br />What Ford manual are you refencing? Would like to get a copy. Seems like there is little info about this OMC combo. I think it was a limited production run with Ford engines. <br />Thanks for the info about the "slow" mode. That really describes what is happening.
 
Joined
Sep 18, 2004
Messages
8
Re: can't go above 2700 RPM without engine spuddering

BALLWORTH there is a form on the planetnautique website that pertains to a engine called GT-40 that was used in the skiboat that used the same fuel injection system as the OMC. I think you caqn down load a copy to try and locate the problem, you can use a code reader from a EEC 4 ford system as it is the same system used in cars but less sophisticated.
 
Joined
Sep 18, 2004
Messages
8
Re: can't go above 2700 RPM without engine spuddering

BALLWORTH try the planenautique downloads and type in GT-40 service manual and you can download the manual into you computer. You may have to join to get the manual but I theink it is worth it because it is better than any after market manual.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: can't go above 2700 RPM without engine spuddering

AIR, I finally remembered to do some reading and yes the SLOW system is 2700 for the Fords. :eek: <br /><br />Ballworth, the senders for the computer for oil and temp are actually switches and are not the ones used for the gauges.
 
Top