Hesitation on acceleration, hard warm starting

[ksukats57]

I have a '95 VIP with a 4.3LX engine. The issue I am having (since I bought the boat last summer) is that when I punch it (to get a skier up, etc) the engine just doesn't pull hard at all for about 5 seconds, then takes off as it should. It does not die and it still builds RPM, just very slowly until about 2000-2500 RPM or so, then it picks up as it should. Its very difficult for people to slalom like this.

Something that may be related is that I have to hold the key over and crank the boat for about 10 or 15 seconds to get it started even when it's warm, my parents have a 91 7.4 litre that fires right up with the first tap of the key.

Last summer I replaced the distributor cap and rotor, spark plugs, and I have been running premium 91 octane fuel, all of which help the problem, but its still there and still annoying. I believe the boat has the mercarb but I'm not quite sure how to tell, maybe someone can help me with that.


Thanks!

 

[mark1905]

Re: Hesitation on acceleration, hard warm starting

Textbook carb accelerator pump issues.

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

I second the accelerator pump. Also check your filters. If you are having a hard time restarting you could have a needle and seat assy bleeding down. With the boat up and running though, the fuel pump would be able to negate that as far as driveability. Sounds like two seperate problems here. A carb rebuild should be done.

 

[Bondo]

Re: Hesitation on acceleration, hard warm starting

I second the accelerator pump. Also check your filters. If you are having a hard time restarting you could have a needle and seat assy bleeding down. With the boat up and running though, the fuel pump would be able to negate that as far as driveability. Sounds like two seperate problems here. A carb rebuild should be done.

Ayuh,.... Ditto, includin' a new acc. pump....

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

ThaNks guys. I wondered if a carb rebuild needed to be done. What kind of cost am I looking at to have this done?

 

[Scott Danforth]

Re: Hesitation on acceleration, hard warm starting

about $50 if your handy with tools and do it yourself, or about $250 at the local marina

 

[Jmunk]

Re: Hesitation on acceleration, hard warm starting

If your mechanically inclined do it yourself. It's actually straight forward, take pics so you know how it goes back together. I have a one gallon can of carb dip that I have been using for a while. Blow all the passages out with air to be 100% sure they are clear and I again dip in the can of cleaner again then hose with water, blow out with air again and reassemble to factory specs. With the manual pretty much anyone can do a carb overhaul.

Here's a tip, use an old cookie sheet pan to dissemble and reassemble on. Keeps all the small parts from rolling away.

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

Use the widest tip screwdriver for power valve removal. Do not attempt to remove the power rod. Just blow air through the air horn passages. Like Jmunk said, you can buy a one gallon dip can at any auto parts store. Some 2 barrels are a tight squeeze getting the sections in, but if you take and slightly egg shape the can you can get the pieces in. It's a 3 beer job

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

can I just clean it with it on the boat and see if that helps? OR can i just fix the accel pump?

Also, where can I find a manual to see how its done?

 

[Bondo]

Re: Hesitation on acceleration, hard warm starting

can I just clean it with it on the boat

Ayuh,... Without Complete disassembly, yer ain't doin' Nothin'.....

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

Ayuh.........NO Complete disassembly required. Shooting carb cleaner down a venturi cleans the venturi only. No way to clean passages without disassembly. Bondo, I stole your AYUH, and I'm not giving it back. I have lawyers for these things.

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

Where can I find a manual that shows me how to do this? I have rebuilt many mikuni jet ski carbs before, but never a marine/automotive one.

Thanks!

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

Manual is with the rebuild kit

 

[Jmunk]

Re: Hesitation on acceleration, hard warm starting

Same concept as a jet ski carb, just larger scale thats all.

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

The carb is a weber 9600s. Can i just replace or fix the accel pump?

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

Your already 75 percent there. You have to break the airhorn gasket anyhow, so you might as well keep going.

 

[mark1905]

Re: Hesitation on acceleration, hard warm starting

FYI that carb is also known as a Weber Y43. May help you when looking for rebuild kits.

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

Ok so I found some old threads that talked about using kits for edelbrock carbs, and Ive found those on Jegs.

That said, once I do that and have the calibration kit, how do I know how to calibrate it? Will i need any special tools?

Thanks

 

[mpdive]

Re: Hesitation on acceleration, hard warm starting

I'm confused why your trying to "match kits". Just my opinion, but there are a gazillion carb kits online that are model specific. I have never tried to match kits. I order the kit for the carb I have. Nothing less, nothing more.

 

[ksukats57]

Re: Hesitation on acceleration, hard warm starting

I'm confused why your trying to "match kits". Just my opinion, but there are a gazillion carb kits online that are model specific. I have never tried to match kits. I order the kit for the carb I have. Nothing less, nothing more.

Just going from the info in this thread.

http://forums.iboats.com/showthread.php?t=45041&highlight=823728