Hesitation

[StylinSupra23]

I took my 90 Comp out for the first time last weekend, it started off running and idling fine and then all of a sudden started experiencing hesitation at take off and surging while driving mostly when I hold between 1000-2500 RPM if I open it up it seems to do OK. It also would not idle much less coast in the no wake zone. I changed the fuel filter, put gas treatment in my tank, and cleaned the carb(as much as I know how) and took it out the next day and it got better. It idles most of the time(barely) and surging has ceased except at low RPM, still definitely won't coast. Am I on the right track? I plan on running a couple more tanks of treated gas through before I do anything drastic. Does it sound like maybe a carb issue? I could have sworn that I filled my tank up before the winter and know I added stabil but for some reason it was not full when I took it out the first day (only had about 1/4 tank). I have heard that if it's not full condensation can rust the inside of the tank which worries me. Could fuel pump/ points condenser have any thing to do with it?

[DKJBama92Mariah]

WATER IN GAS... Thats my first guess anyway. If you stored the boat with only a 1/4 tank, there is likely a good amount of water condensed in the tank. When storing, you should always have the boat with a full tank, if the tank is full, there is no place for the water to condense. Also, when you put it up for winter with a full tank, put some sta-bil fuel treatment in it to keep the gas from going stale. I would also recommend draining the carb as part of a winterization procedure. There is a good procedure for it here: http://www.marinemechanic.com/Workhorse/index.htm Click on the link "How to powertune your holley carb" and go to about the fourth page (there are links to go to the next page at the bottom of each page).

Dont worry about rust, odds are that your tank is plasic, i know mine is on my '92. If you want to check, the tank is under the ski locker at the back of the boat.

You have a couple of options to deal with this. The first, is the route you are taking, just deal with it till you burn all the water out. The other is to drain the tank and fill it with fresh gas (if you do this, dont try to siphon the gas by mouth, i did, and i was laying on the pavement before i knew it. It messed me up worse than anything a did in college, thats for sure, and i did ALOT of stupid stuff.). By the way, DO NOT put alcohol or other "water removing" agents in your tank. The alcohol in these can be hell on the rubber parts of your fuel system, including all those pesky rubber diaphragms in out beloved holley carbs.

If either of the above dont work, holla back and we can explore other routes. I just tend to addressing potential problems with the cheapest and most obvious solutions first. Next on the list is plugs, wires, cap, rotor, points, condenser, carb rebuild, cylinder leakdown test, etc. Lets hope it doesnt get that far.

My second guess tells me, if its not water in the gas, then you've got a problem with the primary side of your carb. The fact that it gets better over 2500 RPM (incidentally, about the time the secondaries open up) makes me think you may have a clog in one of your primary jets. If you have a 4150/4160 carb, you can get a spare gasket and pull the primary fuel bowl off and try and clear the jets with compressed air.

Good luck,
Cheers,
DKJ

[Boiler with a Supra]

While we are on the subject. I have kind of the opposite problem. I took my 88" comp out and its stalling out at 2000 RPM. It will do fine at idle and right up to that magical number and then it just cuts out and dies. ANy thoughts?

[Boiler with a Supra]

While we are on the subject. I have kind of the opposite problem. I took my 88" comp out and its stalling out at 2000 RPM. It will do fine at idle and right up to that magical number and then it just cuts out and dies. ANy thoughts?

[DKJBama92Mariah]

Ok fellas,
Here are the 2 pages from the PCM service manual PDF for diagnosing the Holley 4150/4160. Just remember Boiler, your problem may not just be fuel, it could also be ignition related. Also, im not sure if the svc manual suggests it, but my first suggestion would be to change the fuel filter b/c this is only happening at higher RPM. Anyways hope these are legible and help you some, and i hope i dont get sued for copyright infringement, but the PDF was available online, so i guess im ok. If you cant read them, email me at [email protected] and i'll email you the whole pdf file (14.4MB).

Cheers,
DKJ


http://img.photobucket.com/albums/v55/dkjpika/Boat/HolleyDiagPg1.jpg

http://img.photobucket.com/albums/v55/dkjpika/Boat/HolleyDiagPg2.jpg

[DKJBama92Mariah]

Nevermind about the email,

Here is the link for the PDF download:
http://www.correctcraftfan.com/ftp/new/PCMsvcmanual.pdf

Also, Here is a link with a list of a lot of downloads you might find useful. It's a Nautique site, but has several PCM manuals listed:

http://www.planetnautique.com/CorrectCraftManuals/

Cheers,
DKJ

[StylinSupra23]

Well my problem was carb related; the idle fuel passage was apparently partially blocked. All I had to do is take the air/fuel mixture needles all the way out, spray some B-12 through the holes. When I put mine back in I screwed them all the way in then backed them both out about a turn and a half. Runs great now.