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View Full Version : sluggish post winter engine blues


Capt. K
03-16-2011, 06:40 PM
I have a 1992 Prostar 205 with a 351. I took it out last weekend for the first time this season. It sputtered and coughed as it usually does after sitting for 3 or 4 months, but this time it didn't clear up. I ran it for about 45 minutes and at times I could barey get it on a plane. Other times it sounded pretty good at 3,000 rpm's, but it just didn't sound right.

Today I added sea foam and stp octane boost hoping it would clear up what might be in the gas. I did use sta-bil in the fuel at the end of the season. I ran it for about 45 minutes. After the first 20 minutes, I thought it was clearing up but then she started to cough and sputter. I ended up going back to the dock a couple times, thinking I'd have to get a tow or swim her back.

water in the fuel? Carburator adjustment? General tune up (plugs, wires, etc...)?

help !!!

east tx skier
03-16-2011, 07:29 PM
Did you pour any of the sea foam directly into the carb while idling? I used to do half a can into the carb, kill it, and add the other half in the tank. Let it sit for 20 minutes, then drive it like you stole it and blow all of that old gunk out.

Capt. K
03-16-2011, 07:32 PM
No, i poured all of it (2 quarts) into the fuel tank.

thatsmrmastercraft
03-16-2011, 07:40 PM
You might pop the dist. cap off and have a look a look at the condition of the contacts inside the cap and the end of the rotor. Can get a little fuzzy sitting. Also check both ends of the coil wire for corrosion. Best to use dielectric grease when installing to prevent any corrosion. All the plug wires connected? Sounds stupid but I have caught that before...........once on my boat.

Hoosier Bob
03-16-2011, 10:54 PM
Change your plugs and make sure it is hitting temp. I go through therm's every couple of years.;)

I am assuming you are seeing some smoke?

aggies0025
03-17-2011, 01:09 AM
Remember MOST gas now has Ethanol. Did you add the Sta-Bil for Ethanol?

Capt. K
03-17-2011, 06:55 AM
Change your plugs and make sure it is hitting temp. I go through therm's every couple of years.;)

I am assuming you are seeing some smoke?

I did notice that that my oil temperature was dropping from the normal 150 down to 100-110.
Therm? thermostate?

Capt. K
03-17-2011, 06:56 AM
what causes it not to hit temp?

thatsmrmastercraft
03-17-2011, 09:10 AM
what causes it not to hit temp?

Thermostat stuck open would give you those sluggish characteristics. Might not notice it much in the heat of the summer, but certainly in the cooler temps. You could try tapping on the thermostat housing with a rubber mallet or the handle end of a good sized screwdriver - sometimes the pop free. I would just replace it as they are cheap.

east tx skier
03-17-2011, 10:43 AM
Remember MOST gas now has Ethanol. Did you add the Sta-Bil for Ethanol?

SeaFoam will deal with the ethanol, too. Problem is, if its fuel related, he did not add anything at winterization.

Capt. K
03-17-2011, 11:07 AM
I did add sta-bil during winterization last fall.

WilliM1940
03-17-2011, 11:13 AM
I used Seafoam at layup with fresh 10 percent ethanol gas. I meant to finish up by draining the carb bowls and refilling with avgas but never got around to it. Beginning of February I finally drained the bowls. Each had 1/4 -1/3 cup of gas and approx 1 tablespoon of water. I backfilled the bowls with kerosene. I drain the tank every year and chuck a little Seafoam in with what is left. Point is, this ethanol fuel is crap. My advice based on my bowl contents is never leave the junk in your tank. Start fresh in the spring.

Capt. K
03-17-2011, 08:12 PM
It was the termostat and the time was off, very weird. runs good but oil temp is 175-180 rather than the typical 150. Is this something to be concerned with?

03geetee
03-18-2011, 07:53 PM
Shake up your boat alot at least before the first start in spring to help re mix the contents of your fuel tank, the stuff in your bowls will quickly get exhausted with a few hiccups or small starts.

Works for me anyway, I still treat my fuel but we always shake up the tank before starting anything that has sat for a long time even my mustang.

JTR

oldairboater
03-18-2011, 10:44 PM
Like mentioned above check under the distributor and I would change out my water/separator filter. That is a spring rite for me anyway.

Jerseydave
03-19-2011, 08:21 AM
With engine OFF, look down into carb, hold choke wide open and hit the throttle. You should see 2 strong streams of gas squirting into carb throats. If not, you have a bad accelerator pump in your carb.

Holley carbs are also known for having bad power valves, which can cause a big loss in power.

Also as someone said, remove dist cap and check for corrosion/moisture. If you see moisture inside the cap use a hair drier to dry it up. Do you still have points in your distributor? If so now might be a good time to change them, or convert to electronic.

Hoosier Bob
03-19-2011, 03:13 PM
Calls for a 160 thermostat but if you purchased an auto type you may have purchased 165 or 175. Should not be a worry. Also your fake-o-lake with a new therm will suck a bucket dry. If on the lake I would ask myself when I replaced the impellor last. Also 175-180 with a 165 or 175 thermostat is most likely ok and where it should be. Plugs can burn the slime from wiinterizing with the temps you are running anything under 140 or so and you ain't gonna do it! :D

PS the Skidim therostats last me a ton longer than what I stuck in during a desparate time. 1 and a half years is what I got out of a NAPA thermostat for a 351.It was the termostat and the time was off, very weird. runs good but oil temp is 175-180 rather than the typical 150. Is this something to be concerned with?