PDA

View Full Version : Engine running rough 1st trip this season


TEAL98
04-07-2010, 12:33 AM
And I'm blaming it on a fuel issue. I beleive it to be bad gasoline. I took the thermostat out, didn't know how old it was, and just figured it would probably take double the amount of time to warm up if anything (just like a regular automotive vehicle).

So I'm putting everything back together, including tapping out my exhaust manifolds to replace the factory plastic plugs with brass ones. Forgot to order the T-stat:mad: So I pull the old one, not a big deal. Bring the boat home and fire it up on the hose. I had put one quart worth of Sta-Bil in it upon winterization, into my full tank. Boat ran fine for the 30-45 minutes I had it on the hose, but never reached temperature, nor did the block ever get even warm.... ehh, whatever, no RPMs over 1k, and the engine cover not being down could have something to do with it.

So I got on the lake, boat ran fine whenever I gave it gas, but every other time it wanted to stall when I brought it back down to idle. Sometimes, on the hole-shot, I'd have to delay my "idle-to-WOT" with a slight touch above idle and then hit it WOT, just because it would want to spit and act stupid, had I not proceeded the way that I did. Even going down the lake, intermittently going from cruise (2800RPMs) to WOT, it would begin to run rough climbing through the RPMs, but then smooth out not even seconds later. Like I said, sometimes it would, sometimes it was fine. Temperature hardly moved to 120 the whole time I was out on the lake. Gotta get that T-stat from skidim tomorrow as well, since I don't plan on going back out onto the lake until next weekend anyways.

So I get back to my mother's, talked to her husband, he said when he used sta-bil his first winter, that his boat acted the exact same way his first trip out, and didn't clear up until the second fill-up. He's been using seafoam ever since and said he's not had a problem yet.

Not really looking for advice, just pitchin' a fit, this is my first inboard and first winterization/summerization that I've done so I'm still learning a few things for sure. Tell me what you guys think... and yes I do expect the "hey stupid" so I'll listen to those as well:D

coz
04-07-2010, 09:50 AM
The engine issue sounds like something I was experiencing. My boat would fire up and run very rough at idle but there was no hesitation when I opened up the throttle and it turned out to be the idle air control valve (IAC). $120 at napa auto and it fixed the problem.

Chicago190
04-08-2010, 05:00 PM
Problem isn't necessarily bad gas. Did you change spark plugs? How old are the plug wires? Cap and rotor been replaced recently? Also, your boat not getting up to the proper operating temperature could be the problem.

pkskier
04-08-2010, 06:07 PM
I would check into the distributor, sometimes when it is cool the heat of the engine can cause some moisture to accumulate under the cap and cause the symptoms you described.

Monte
04-08-2010, 06:15 PM
Water in the gas.

bbeach
04-08-2010, 06:30 PM
Throw 3 bottles of HEAT into the gas, run it out, fill up with a fresh tank of 91 octane... Might even throw another bottle of HEAT into the new tank of gas... I had this problem a few years ago... just a bit of water in gas tank from storage.

TEAL98
04-11-2010, 03:26 AM
I'm a little confused on skidim's website between 2 thermostats. Anybody have the part # or directlink for the '98 Indmar Vortec MX?

Chicago190
04-11-2010, 01:05 PM
I'm a little confused on skidim's website between 2 thermostats. Anybody have the part # or directlink for the '98 Indmar Vortec MX?

Should be this one: http://www.skidim.com/prodinfo.asp?number=R026002

The 143 and 160 degree drilled are specific to the LT1.

You'll probably want a new gasket, or you can make one yourself out of gasket paper available at any hardware store. Depending on the thermostat housing on your engine you'll want: http://www.skidim.com/prodinfo.asp?number=98-5006 or http://www.skidim.com/prodinfo.asp?number=53-1058

JimN
04-11-2010, 01:56 PM
And I'm blaming it on a fuel issue. I beleive it to be bad gasoline. I took the thermostat out, didn't know how old it was, and just figured it would probably take double the amount of time to warm up if anything (just like a regular automotive vehicle).

So I'm putting everything back together, including tapping out my exhaust manifolds to replace the factory plastic plugs with brass ones. Forgot to order the T-stat:mad: So I pull the old one, not a big deal. Bring the boat home and fire it up on the hose. I had put one quart worth of Sta-Bil in it upon winterization, into my full tank. Boat ran fine for the 30-45 minutes I had it on the hose, but never reached temperature, nor did the block ever get even warm.... ehh, whatever, no RPMs over 1k, and the engine cover not being down could have something to do with it.

So I got on the lake, boat ran fine whenever I gave it gas, but every other time it wanted to stall when I brought it back down to idle. Sometimes, on the hole-shot, I'd have to delay my "idle-to-WOT" with a slight touch above idle and then hit it WOT, just because it would want to spit and act stupid, had I not proceeded the way that I did. Even going down the lake, intermittently going from cruise (2800RPMs) to WOT, it would begin to run rough climbing through the RPMs, but then smooth out not even seconds later. Like I said, sometimes it would, sometimes it was fine. Temperature hardly moved to 120 the whole time I was out on the lake. Gotta get that T-stat from skidim tomorrow as well, since I don't plan on going back out onto the lake until next weekend anyways.

So I get back to my mother's, talked to her husband, he said when he used sta-bil his first winter, that his boat acted the exact same way his first trip out, and didn't clear up until the second fill-up. He's been using seafoam ever since and said he's not had a problem yet.

Not really looking for advice, just pitchin' a fit, this is my first inboard and first winterization/summerization that I've done so I'm still learning a few things for sure. Tell me what you guys think... and yes I do expect the "hey stupid" so I'll listen to those as well:D

You need a thermostat in that motor. When the motor is really cold, the temperature reported to the ECM causes it to enrich the fuel mixture and a cold motor is never efficient. The heads and block never get hot enough to allow the fuel to burn well and completely. Put a T-stat in and it should run a lot better.

TEAL98
04-12-2010, 12:00 AM
Ordering a new stat tomorrow, I'm guessing I should have it and be ready for this upcoming Saturday. Thinking about pulling the tank anyways, as my damn fuel gauge had started acting screwy the day after I got. Won't read full when the boat IS full... so I can kill 2 birds with one stone there. Just can't wait to get back out on the water and get on the wakeboard:(

87MCProstar
04-18-2010, 04:52 PM
Sounds like the same problem I had. Water in gas, through some dry gas in filled tank and was good after second fill up

TEAL98
04-20-2010, 03:12 AM
Well, I talked to Karen at skidim (she actually called me) on Tuesday, and had told her what I needed, and that if possible I would like to have it by Friday, but no later than Saturday if possible. Reason being, I wanted to get back out on the water (don't we all) ASAP. The thermostat showed up in my mailbox Friday, I put it in Saturday morning, stop by Shell on the way out to the lake and put just over 1/2 tank back in, that I had ran out the weekend before. (I top off with 93 octane every single time I go out)

Got to the dock, slipped the boat in, fired it up, made sure it didn't overheat, and idled out of the no wake zone. Boat ran 100%, couldn't be happier with it:cool: Today, my buddy and I actually went out again, stopped by a local marine store and picked up the only handle and rope they had in stock, and I got my first couple of runs in this season. And MAAAAAAAAN IT FELT GOOD! My buddy is a novice driver, and I showed him how I needed to be pulled up. Guess the boat had a little more "umph" than I had expected, because it felt like I went from laying in the water, to be yanked a couple feet in the air. Needless to say, I ate it, told him to take it easier on the next pull, got some ski time in, boat ran top notch, couldn't be happier with it!!!:cool: