Engine misfiring and cannot figure it out

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   Folks:

Looking for some mechanical insight:

Boat:  1994 Ski Nautique
Engine:  5.8 Pro Boss, Pro tech efi
Hours:  240 original
Condition:  Mint show room condition, I am the third owner

Issue:  Intermittently the engine seems to miss fire at either 200o rpm or at 3000 rpm.  The boat makes a shaking sensation, like the shaft is out of alignment, though the shaft, prop, and cutlass bearing are fine.  It is almost like half of the cylinders are firing or perhaps only half of the cylinders are getting gas while the other four are being shorted of fuel.

Any ideas of comments?  I am in rural Alaska and a ways away from a mechanic.  Would greatly appreciate some mechanical advice and insight.

AKskier 

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AKskier Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-14-2016 Location: Alaska Status: Offline Points: 3	Post Options Post Reply Quote AKskier Report Post Thanks(0) Quote Reply Topic: Engine misfiring and cannot figure it out Posted: August-05-2016 at 10:04pm
	Folks: Looking for some mechanical insight: Boat: 1994 Ski Nautique Engine: 5.8 Pro Boss, Pro tech efi Hours: 240 original Condition: Mint show room condition, I am the third owner Issue: Intermittently the engine seems to miss fire at either 200o rpm or at 3000 rpm. The boat makes a shaking sensation, like the shaft is out of alignment, though the shaft, prop, and cutlass bearing are fine. It is almost like half of the cylinders are firing or perhaps only half of the cylinders are getting gas while the other four are being shorted of fuel. Any ideas of comments? I am in rural Alaska and a ways away from a mechanic. Would greatly appreciate some mechanical advice and insight. AKskier

8122pbrainard Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045	Post Options Post Reply Quote 8122pbrainard Report Post Thanks(0) Quote Reply Posted: August-05-2016 at 10:14pm
	Eric, Welcome to CCfan. I may be mistaken but I don't recall another member from Alaska so it's great to add another state to the list. What you are describing sure sounds like another Pro tech on it's was out. Explore the site and you will find several threads on converting back to a distributor and a carb. The FAQ thread in the maintenance forum is a good place to start. It has links to the Pro Tech problems as well as almost anything else. If you can find what you are looking for, ask. I feel the members here are the best at any issue.
	54 Atom 77 Tique 64 X55 Dunphy Keep it original, Pete <

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: August-06-2016 at 1:24am
	Eric: I agree with Pete. It sounds like the ProTech engine management system is starting to fail. Some (myself included) feel that the ProTech is a ticking time-bomb that will eventually implode and fail. You appear to have the double-whammy with the throttle-body fuel injection ProTech combo. Parts for the ProTech and the throttle-body fuel injection are no longer available. May be time for a retro-fit back to "old school". JQ
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

AKskier Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-14-2016 Location: Alaska Status: Offline Points: 3	Post Options Post Reply Quote AKskier Report Post Thanks(0) Quote Reply Posted: August-06-2016 at 4:24pm
	Thanks for your help, after 24 hours I have more info than I can imagine. I will go to FAQ and search Prp Tech and see what I can find. JonnyQwest has also been amazingly helpful. 8 weeks to ski before the big chill and ice happens in Alaskaland

gun-driver Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127	Post Options Post Reply Quote gun-driver Report Post Thanks(0) Quote Reply Posted: August-07-2016 at 12:57am
	You may also want to check your fuel pressure before replacing the whole package. I was on one of the other boat sites guy had same problem with that set up, ended up being the fuel pump or a dirty fuel pump screen can't remember exactly.

desertskier Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: December-19-2006 Location: Az Status: Offline Points: 1115	Post Options Post Reply Quote desertskier Report Post Thanks(0) Quote Reply Posted: August-08-2016 at 12:14pm
	Check the voltage at the 12.5amp breaker on the back of the engine, It should be close to battery voltage. The Protec system will act up if that voltage is low. Not exactly sure how low it can go but I think it is safe to say it needs to be greater than 10Vdc. The key needs to be on and if possible the engine running.

Engine misfiring and cannot figure it out

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