1996 OMC Cobra 5.8 FSI Ford engine doesn't rev over 4000 rpm

[hushmandco]

My engine RPM doesn’t go above 4000 psi while in neutral. When in gear it tops as 3600 -3700 and and as soon as I push the throttle more , you can hear the throttle opens and makes the "air hungry" noise but the spark cuts at 4000 rpm while in neutral and stays there back and forth around 4000 +- 50 rpm.

I replaced the distributor cap and the floater arm but still the same results.
I tested the fuel pressure ( high pressure ) and it's sitting on 32 PSI no matter what.
when I Rev up to 4000 and as soon as the engine cuts off, the pressure goes to around 36 or so, and when I pull the throttle back it gets to 32 psi again.
I have read about the water temperature switch and messed with it a little bit, disconnected it and used a multimeter to measure the resistance between the pin and the engine body, and nothing . like it's completely disconnected. I did it while engine was cold and while engine was at 150F. same results.
I ordered the part and waiting for it till the next few days.

Is there anything else that I might need to check before the part arrives?
Does anyone know if the bad water temperature sensor has anything to do with Rev limiting?
where is the diagnostic port on these engines and how can I buy one?

Thank you very much in advance!

 

[alldodge]

Have some but very little info on the motor. No expert but don't see the temp switch causing a rev limit issue. Fuel pressure is within limits (show 31 to 39 psi)

If its misfiring do to rev limit kind of thing, I have no clue.

Use a timing light and check advance to see if what your getting and what happens when it starts acting up

 

[Scott Danforth]

Check the RPM with a shop tach. You may be spinning faster than your tach is showing and you may be hitting the rev limiter

 

[hushmandco]

Have some but very little info on the motor. No expert but don't see the temp switch causing a rev limit issue. Fuel pressure is within limits (show 31 to 39 psi)

If its misfiring do to rev limit kind of thing, I have no clue.

Use a timing light and check advance to see if what your getting and what happens when it starts acting up

I timed it and it’s on the spot however just to make sure i made it off by few degrees up and down and no results

 

[hushmandco]

Check the RPM with a shop tach. You may be spinning faster than your tach is showing and you may be hitting the rev limiter

That’s a good suggestion. ordered an RPM meter on Amazon and will test it soon.

 

[Scott Danforth]

That’s a good suggestion. ordered an RPM meter on Amazon and will test it soon.

you can borrow them from your local autoparts store

 

[Reactivity]

I had a similar issue on a ford 5.0l. I the engine would rev up great in neutral all the way to red line. The second I was in the water in gear it would sputter and backfire around 2000 rpm. Turned out to be the spark plug wires. They are certainly worth checking if you haven't changed them in a year or so.

 

[Zify]

I have a similar issue with my 5.8 omc cobra. I have a 1996 Cris Craft running a 14.25x19 prop. I can’t get rpm’s over 3200.

Any luck finding the issue?

 

[Scott Danforth]

I have a similar issue with my 5.8 omc cobra. I have a 1996 Cris Craft running a 14.25x19 prop. I can’t get rpm’s over 3200.

Any luck finding the issue?

first, welcome aboard, however please do not hijack other threads

do the basic checks
compression numbers
fuel pressure numbers

 

[Zify]

first, welcome aboard, however please do not hijack other threads

do the basic checks
compression numbers
fuel pressure numbers

Sure man. Just asking if the original post was resolved and lessons learned. I plan on running through a long list this weekend but was just seeing if there was something to learn here. I’ll post a unique thread once I know more.