Irene's hesitation

[BMFScout]

So the boat ran great over the week in Mizzou until the last day. It runs great up until about 2800 rpm's and then cuts out to like 2300, then runs right back up to 2800. It almost sounds like a rev limiter. It starts great and cruises around fine as long as you stay around 2500 rpms. We checked the vaccum lines and fixed one small leak on a plug, but that didn't do anything. Also thought it might be bad gas so we added a few gallons and put some treatment in there to dry it out if there was water in it. Also changed the low pressure filter and drained the water separator. Any ideas?

[mudtoy67]

Just give her a little whiskey and that should take care of all her inhibitions...









Oh, you mean the boat...:flipoff2:


How's your fuel pressure? Could there have been some trash in the tank you picked up making it not get enough fuel pressure at higher rpms? How's the regulator? Vacuum line good?

[agjohn02]

its a boat. what do you expect?


is it carbed or injected? sounds like a fuel pressure issue.

[mudtoy67]

Also check the distributor. My ford would go to running like shat if I got condensation inside. Dry the underside of the cap and blow some air around the optical pickup.

[jerryg79]

is it carbed or injected?

way to stay informed:flipoff2:

[Seth]

My guess would be trash in the fuel lines somewhere. Had it happen once years ago, turned out it was those flying ants had gotten in the lines.

Hows it run above 2800?

[BMFScout]

It doesn't, it cuts out at 2800.

Will check the distributor.

John: It's got a sweet double pumper on there. :rainbow:

[Fredo]

It's weird...it really acts like a sensor problem or vaccuum leak because it cuts out at 2800 regardless of load or no load. Thought it might be some common ford disease among the injected motors. I guess it could be something in the distributor, have to check that out too.

[mudtoy67]

Maybe base timing is too far advanced? Did you unplug that little jumper in the distributor wiring to set base timing (like you do on TBI chevys)?

[KrazyKarl02]

If that does not work, try removing the blue oval.....

[BMFScout]

I almost think it has to be a rev limiter. Do you guys know how Ford limits rpm? I read somewhere that it pulls fuel to limit rpm. Even if I hammer it down all the way, it won't go past 2800 rpm, in neutral either and runs good up until that point. Think it could be a bad oil pressure or temperature sensor causing it to go into limp home mode. Do you think it has limp home mode?

[robertf03]

Is it consistent? Find out whats cutting out, fuel, spark, or both.

[BMFScout]

Pretty damn consistent. It starts on a dime and then runs normal right up to 2800, drops to 2300, then back to 2800, etc. It goes woo-woo-woo-woo... :) It doesn't matter how much throttle I give it either.

My current theory is one of the computer's temp sensor or oil pressure sensor connections are loose or the sensor went bad.

[BroncoJo]

I almost think it has to be a rev limiter. Do you guys know how Ford limits rpm? I read somewhere that it pulls fuel to limit rpm. Even if I hammer it down all the way, it won't go past 2800 rpm, in neutral either and runs good up until that point. Think it could be a bad oil pressure or temperature sensor causing it to go into limp home mode. Do you think it has limp home mode?

to my knowledge ford does not have a limp home mode on older gas motors.

[BMFScout]

Is 2000 older? The motor is a 351W GT40 multiport for those that didn't follow the other thread. I don't know if it has limp mode or not, just seems to be pretty consistent.

[agjohn02]

had a clogged fuel filter on the tahoe once. it did the same thing, neutral or not.

[BroncoJo]

Is 2000 older? The motor is a 351W GT40 multiport for those that didn't follow the other thread. I don't know if it has limp mode or not, just seems to be pretty consistent.

The only motors I know have limp home mode are diesels, the 6.0 and 6.4. I have never seen a windsor with limp home mode.

[robertf03]

Jimmy its not the limp mode you are thinking of where the computer abandons controls and goes to an analog system like the TBI computer does. It deals with each sensor individually and will throw a code if there is a problem.

There is no oil pressure input to the computer. Maybe a kill switch was added, but it is not in the pcm.

I think it will be very easy to fix once you narrow it down to fuel, spark, or both.

I'm betting its fuel pump/pressure, coil, or ICM.

[Fredo]

I'm betting it's the S.L.O.W. cuircut. One of the switches has either become disconnected or failed, because it hangs out at 40psi+ oil pressure and never goes above 170 degrees. Check out this page I read out of the 301 page diagnostic manual on the proboss 351.

[BMFScout]

That has to be it. Once again, John Cox is worthless. ;) Thanks for the input guys. I'll have Fred report back Thursday night. We have an important business meeting tonight at 1000 Ballpark Way.

[agjohn02]

karl gave the only real advice in the whole thread. after that i had nothing to add.

[jerryg79]

hey jimmy, does this boat require one of those pumps to change the oil. If so I have one sitting at my mom's house if you or anyone else wants it.

[agjohn02]

hey jimmy, does this boat require one of those pumps to change the oil. If so I have one sitting at my mom's house if you or anyone else wants it.

if it looks like these, i know jimmy already has a few of them.

[jerryg79]

if it looks like these, i know jimmy already has a few of them.

cox pumps? I thought those were your bag?

[agjohn02]

tell that to the little round hickey on your left thumb

[BMFScout]

inboards have a hose you can stick through the drain plug which is conveniently located in the middle of the boat. thanks though, I just pump pills much easier.

[Seth]

Sounds like you kinda have it narrowed down, with some John Cox Insecurity to boot, but just for grins, can you pull codes off this motor? Do you have a "check engine light?"

[Seth]

Two things after reading that tech page. 1 - Don't challenge Fred if he tells you he knows something. 2 - Interesting that the comp is an EEC-IV. I guess they kept the system for marine use after they changed the autos.

[BMFScout]

probably should have a check engine light but we don't. fred sat out on the meeting tonight to fix the boat. it was the oil pressure sensor. Fred wins again! I tried real hard in my e-search to beat him, but it was futile.

[Fredo]

Yeah, the oil pressure switch was bad. If we would have had the audible alarm hooked to the system, we would have known right off the bat what the problem was. I guess we could find the optional audible alarm and put it on there, because the lesbo ex-con forgot to stea...i mean remove it from the boat that the engine came from. I also adjusted the throttle so it now actually opens WOT. The way it was when we first installed the throttle cable, there was about 3/8's of an inch of the throttle that it wasn't using. Plus, with that vaccuum leak we found, it was probably pulling timing so I'm kind of interested to see what it will be like now.