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Old 04-06-2005, 03:57 PM
Ty 73 Ty 73 is offline
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idle and acceleration problem

Hello all. Great forums with a wealth of info. I was wondering if you might have any suggestions for the problems I have been experiencing.

I've got a 1980 prostar with the 351 engine. It has the holley 4 bbl carb.

This boat has been in the family since it left the factory and has been serviced regularly.

Last summer it was running great until near the end of the season when we started having two problems. After warming up the idle would become rough. Specifically, the engine would cycle through a series of "surges." Almost like someone was applying throttle and backing off over and over again. Each surge lasts about a second and then the engine would almost die and then surge again. If you can imagine a repetitive throttle, back off, throttle, back off, throttle, back off...I could only break the cycle by bringing the boat up to speed and then returning to idle. The second problem was with hesitation during acceleration. The engine would almost die and then suddenly pick up. In fact, sometimes it would die.

Both of these problems only occurred when the engine was up to temp. The engine never overheated. Both problems were inconsistent as sometimes we skied for hours with no problem at all. However, the problems did become more and more frequent toward the end of the season.

I planned to have the carb professionally rebuilt over winter. In fact, I did replace the secondary diaphragm myself and did an overall inspection of the carb at the end of last year but that didn't seem to help.

Now I'm considering the breaker points as the problem instead of the carb. I've decided to install the electronic ignition conversion kit before paying someone to monkey with the carb.

I was wondering if anyone else has experienced a similar problem. Hesitation before accelerating is fairly common, but I've never heard anyone describe surges during idle. Anyone?

Do you think the electronic conversion will help?

Also, do I need to remove the resistor after installing the conversion? I think I read somewhere you should.

Thanks for your time and appreciate any suggestions.
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Old 04-06-2005, 04:04 PM
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jsonova99 jsonova99 is offline
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Welcome to the site! My '91 came with the electronic conversion already done, but I think it's a relatively simple job anyway. Whether that is your problem or not I would still do it, you'll be glad you did in the long run. I'm still learning how to diagnose things like this, but I think it sounds like a carb problem. I just rebuilt mine myself, it was pretty easy, I bought a kit ofr $45 had everything I needed. I'll have to get back to you though on how well I did, I haven't had a chance to run it since finishing Anyway, I'm sure some more folks will chime in with better advice than me, but I say install the new ignition and rebuild the carb.
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Old 04-06-2005, 04:14 PM
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BrianM BrianM is offline
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It does sond like a fuel problem to me as well. Maybe a dumb wuestion but did you already check your fuel filter as well as the screen in the tank for debris? I would check these things first before doing any other work. You might just have some 'junk' caught up somewhere.

Do change to electronic ignition it will make life easier. Yes you do remove the resister when installing. If you are fairly mechanically inclined the swap is only about a 30 minute job.
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Old 04-06-2005, 04:18 PM
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east tx skier east tx skier is offline
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I had a hesitation with accelleration issue that was fixed with a rebuild (even though I ultimately ditched the carb due to hot stall issues). In addition to the fuel filter and tank screen, check the screen where the fuel line meets the carb.

Also, this probably isn't the culprit, but cleaning your flame arrestor is always a good idea.
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Old 04-06-2005, 04:57 PM
Hunterb Hunterb is offline
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From your description of the problem it sounds like your engine is 'loping'. This may be caused by an intake leak somewhere. I would think that it is a fuel problem and not electrical for sure. It's quite cheap and fairly easy to rebuild the carb so I would do that. I would carefully check the intake manifold gasket and the gaskets between the carb and the spacer and the spacer and the manifold as well. If it's a 1980 carb and it has not been redone yet then it is due for sure and that, plus maybe some new gaskets, will in all likelihood solve your problem.

Good luck

Bruce
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Old 04-06-2005, 05:23 PM
Ty 73 Ty 73 is offline
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Thanks for the suggestions. I'll recheck the fuel filters and screens. I'll post back when I have a chance to do the conversion and get back on the water.

Bruce- "loping"...that sounds like what I may be experiencing. It's really odd because it's so inconsistent. Sometimes the boat idles just great, then the next time I come down to idle it starts surging again... and neither problem is an issue until the boat has warmed up. I'll also add that starting is not really a problem. Even if it dies during acceleration or I kill it while it's surging, it usually starts back up no problem.

Thanks again, Ty.
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Old 04-06-2005, 06:04 PM
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DanC DanC is offline
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Like everybody said, sure sounds like a fuel issue. Definitely start with the easy stuff. Open up your gas tank and check for debris, condensation (water)... Then work your way up through the screens and filters to the carb. I would blow out the fuel line (I like to eliminate the easy to check things even if they are a remote chance). As Doug pointed out, the small screen in the carb at the end of the fuel line is called out as an annual cleaning item in the maintenance manual. After that it is fun time with the carb
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Old 04-06-2005, 07:36 PM
Star92 Star92 is offline
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The fact that you are experiencing hesitation during accelleration points to the carb. maybe the powervalve is bad. A renew kit from holley (got mine from skidim) will come with a new one and also all new gaskets, needle and seat valves, ect. This would be a great idea. As far as the loping, you should also check your fuel pump. The vent tube coming from the top of the pump leading to the carb. If drops of fuel are travelling through the tube, its bad, and will cause loping and rough idle. I had a boat in the past that did the same thing. Also check your float levels, if the boat is rocking in the lake, with too much gas in the bowls, it will pour out into the intake doing the same thing. This would usually flood the boat making it hard to start after a period of floating and the the boat rocking without the engine running. Like was stated earlier, a vaccum leak somewhere in the intake system would definetely cause similar symptons. The ignition is the best money you will spend. Hope this was some help, good luck. I just rebuilt my carb, it wasn't that hard, took about 2 hrs., but if you don't feel comfortable, and don't mind spending the money, take it to a professional.
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Old 04-06-2005, 10:27 PM
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betsy&david Harrison betsy&david Harrison is offline
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Exact same problem...

Wow! Thought you had my boat there for a minute. Our 93 PS 190 did the same thing. We had to put a new carb on it and the entire problem went away. Just my 2
Betsy
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  #10  
Old 04-07-2005, 06:26 AM
jimmer2880 jimmer2880 is offline
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Like everyone has said on this board - sounds like a carb problem. Rebuild it. It's not hard. I'm no carb expert, the first time I saw one in pieces was when I rebuilt one on my old boat.


I also strongly recommend the electronic ignition... BUT - wait till you have your current problems fixed first. The conversions Rarely go bad - but every now & then I hear of one with trouble. It would really stink to not know if it was your conversion, or the carb that was causing the troubles.
Good luck - the folks on this site are top-notch and can answer ANY question.
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