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Always something RPM Limit

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bdolnik

Member
"Just when I thought I was get

"Just when I thought I was getting things figured out the following happened this weekend. Ran about 20 minutes South to get gas... everything seemed fine, temps ok, boat ran well. Took on 25 gallons in each tank (each tanks holds 125 gallons). After idling back out of marina, powered up for the cruise home and had the port engine drop RPM's just past 2k. Now I've had the RPM limiters kick in before and it affected both engines, and sounded the warning horn and illuminated the check engine lights. This time it only limited the port engine (boat yawed terribly) and did not sound any alarms. Temp showed normal, about the same on both engines.

So I'm completely stumped. Any ideas on what to look at? These are 1996 Crusader 454XL's. I was able to idle home at 1200 RPM on both engines no problem.

It doesn't seem like it would be a fuel problem to me as the cutout was not gradual, it was like a switch going off right past 2000 RPM."
 
Did you check the distributor

Did you check the distributor cap for internal arcing?

Do these have ECU's - full computer control or are they the hybrid with the electronic distributor and the carbs? if ECU - scan for codes as sensors are known to fail anytime.

Was it running smooth and just rpm limited or a bit rough?
 
"I have not checked the distri

"I have not checked the distributor cap, I will once I fix the engine hatch which just decided to stop working


I believe these are the hybrid, electronic distributor with carbs?

Yes, running very smooth and then just past 2100 RPM an immediate "cut-off" to idle."
 
"Mark,
What scanner do you re

"Mark,
What scanner do you recommend? Will an automotive scanner do or does it require one specific for Crusader? I have twin 454XLi.

David"
 
"David: concur with Joe - RIND

"David: concur with Joe - RINDA is the leader in this department.

Bryan: the "cut-off to idle" is a bit confusing. Are you saying once your RPM exceeds 2100, something lowers it to idle (+/-)?"
 
"Yes, Mark. Throttle up both e

"Yes, Mark. Throttle up both engines trying to get on plane and the port engine drops to idle after getting to about 2100RPM. Very similar to a problem I had before when the starboard engine was overheating. Only in that case both engines cut back, and the horn and check engine lights came on. It was also apparent on the temp gauge that something was wrong.

That's what is so confusing about this, no horn or lights, and it's only the port engine that cuts back. Starboard engine continues increasing RPM and boat yaws horribly. Temp gauges are normal on both engines.

I'm at a loss for what to check?"
 
"Bryan:

You made me look up

"Bryan:

You made me look up some parts....best as I can tell, you have a computer, with the standard suite of sensors but it only controls the spark, not the fuel delivery. That is independent of the computer and done exclusively by the carb.

The previous experience sounds like the computer rev limiter kicked in, as you indicated with the light and the horn. This one is different. I'd start with the basics and concentrate on the non-computer controlled stuff; ie fuel. Could be something as simple as the oil pressure switch controlling the fuel pump is marginal and goes intermittent with the engine vibrations at 2100. I'd hook a test light into that circuit and see what happens at 2100. If that's ok, check fuel pressure at the carb.

Could also be a sensor giving a bad reading, but not far enough off to set a code. The drawing of that ECU leads me to believe it is NOT a MEFI-1 based system, so this maybe a very crusader specific issue."
 
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