'93 Sunsport acceleration issues

[kvand347]

Lately this problem has been getting worse. Upon leaving the dock (idling for 3-4 min.) I try to get up to speed and the boat will bog down and sometimes a backfire is heard. The problem exists when placed in neutral and revving as well. Sometimes it will clear itself when I get back down to idle and then hit it, sometimes I have to shut down motor and restart. Usually the shutdown was all it took and the boat would then run perfectly all day long. Now, it isn't working as well and multiple shutdowns are needed. Today it cleared itself but still had a miss at times.

I'm thinking it has something to do with the PROTEC system. Any suggestions besides dropping $500 for a conversion? I'm not the type to throw parts at something and hope it works out!

Important to note that when it does clear itself of the problem, it runs great. WOT is ~4300 rpm's at 42 mph with no miss. The bogging is usually around 3200-3600 rpm's.

[kvand347]

Anyone?

I'd like to start digging in to it today since I have a couple booze cruises coming up before I'm back to work!

[kvand347]

Took it out tonight. Ran like a champ...no issues at all.

There are only two things that I can think of that I did differently.

(1) I didn't gas up before going out.

(2) I shut the boat off after I docked it to pull my truck out of the launch instead of letting it idle and warm up for several minutes.

Why do I get the feeling like I am just talking to myself here...no one has an idea??

[TitanTn]

Sorry man, but that one doesn't make a lot of sense to me. It clears up for the whole day? I would agree that it sounds electrical versus mechanical, but the behavior is odd and sporadic. It seems that something mechanical wouldn't clear up and work the rest of the day. Hard to diagnose.

[kvand347]

It doesn't make a lot of sense to me either. Yes, it usually only does it when we first start to go out. After that I can shut it down, start it up, cruise, whatever, and it seems to be gone. Sometimes it takes me several tries to clear it up, but I have never had it NOT clear itself.

After reading my PCM manual, it seems like it is going in to limp mode. I know from reading it does this for two reasons: (1) overheat and (2) low oil pressure. I have never seen my temp guage go past 160-170. Most of the time it is below 160 while running and only reaches 160 if I stop for awhile. My oil pressure is usually around 60-70. I know that shutting down the engine each time restarts the PROTEC and will clear out of limp mode only if the temp and oil sensors are within spec.

When I am having the bogging problem, I usually just key it on and off until I'm able to accelerate again. That is hardly enough time for the engine to cool down!

Stumped!!

[Jetlink]

Stumped as well... My only input is sounds like some electrical gremlins put there by PCM... Not too familiar with anything newer than my boat from a fuel delivery stand point, are you carbed or some form of TBI or fuel injection? I know mine will sometimes stumble coming off idle if the engine is heat soaked after sitting. I can get up to about 2200-2500RPM and the engine will start to struggle. This doesn't happen when the engine is cold or I am just starting out and is a recent development for me.

[cadunkle]

Check your timing advance. I'm not familiar with those injection units but it may still have a mechanical advance, if so it may be sticking. Aside from that I have nothing of value to add to a discussion on fuel infection, aside from ditch it and put a carb on it.

[Jetlink]

Check your timing advance. I'm not familiar with those injection units but it may still have a mechanical advance, if so it may be sticking. Aside from that I have nothing of value to add to a discussion on fuel infection, aside from ditch it and put a carb on it.I expected that response from you and I love it. I am having something funny going on with my airport car, it keeps throwing an error code and I think it has to do with fuel delivery...grrr!!!

[kvand347]

Stumped as well... My only input is sounds like some electrical gremlins put there by PCM... Not too familiar with anything newer than my boat from a fuel delivery stand point, are you carbed or some form of TBI or fuel injection? I know mine will sometimes stumble coming off idle if the engine is heat soaked after sitting. I can get up to about 2200-2500RPM and the engine will start to struggle. This doesn't happen when the engine is cold or I am just starting out and is a recent development for me.

I am carbed...the typical holley 4160. The PROTEC involves the ignition side of things. My guess is with yours...something electrical.

FWIW--Took it out all day today and had ZERO problems. Again I did not let it idle at the dock and I gassed it up after taking it out yesterday. I'm starting to thing it has something to do with one of these things...

[kvand347]

Check your timing advance. I'm not familiar with those injection units but it may still have a mechanical advance, if so it may be sticking. Aside from that I have nothing of value to add to a discussion on fuel infection, aside from ditch it and put a carb on it.

Not sure how to check it since I do not have a distributer. Instead, I have an interrupter. Not sure if I twist that like you would a distributer to change the timing. FWIW--I was reading 10* BTDC @ 700rpm's without the knock sensor disconnected. PROTEC uses a cruise mode that advances the timing 8* to provide max fuel economy and power. I did not check the advance timing which should be 26* @ 3600 rpm's.

If my timing is not advancing, wouldn't I consistently have poor power? I'm clueless to this system!!