Fellas,

I'm having trouble with my GTR35. It has Mikiuni carb, Marsh Mellow exhaust, heads decked .060, performance cam, advanced timing key, Billet push rods and new ignition coils. I actually just bought the boat from a MMT member recently so some of you may know exactly what to do and who I'm talking about . I'm new to mud motors so I'm out of my league with all this modification. The problem occurs when under load (in the water). It will start, idle, and rev thru 4000rpm with no problems out of gear. Reverse works. Launch it, take it off the trailer spin around and begin to go and....... spitting, sputtering, back firing...... It will go in gear, idle and not much pass that. If I squeeze the throttle, it wants to give out and do the above mentioned characteristics. I replaced the spark plugs, fuel lines and fuel filter. The carb is clean so its not there. Whats my next move? Fuel pump?

***Is there some adjustments to the carb that I can make? fuel to air mixtures?***

PLEASE - 0 - PLEASE help a brotha out!!!

Also does octane levels make a difference?

Are you wires under the trim control panel getting pinched? Look for chaffing causing the motor to ground out. I had a wire get pinched by the trim motor just FYI.

What plugs did you use and what did you set the gap at? Are you using a clear fuel filter? Is there bubbles in it? I would say look at the stuff you changed first.

As far as octane goes, I would be running premium fuel.

I've seen one with a bad coil do the same thing. Out of the water the rpm's were fine and it sounded good.It worked in reverse with a bad coil but would do exactly what yours is doing when you would engage the clutch.

First reply in Thirty minutes...man y'all are the shit. Thanks for the quick fire responses.

WestEndAngler - I haven't checked that. stay tuned...

cb5331 - I replaced a worn out set of ACDelco with NGK Platinum gapped at .30. The old fuel filter was clear and YES I did notice bubbles appearing to come from the bottom of the old one (new ones has no bubbles). So I replaced the lines and filter thinking dry rot or a split in the line I can't see. Nothing helped. Are the air bubble a source of something else?

dog walker - Thought about that but didn't think my odds are that bad when I test drove it on the August 6th and ran like a scaulded dog (good), picked it up on the 9th and immediately started to have problems. Would a ride from TX to LA jar or jolt or break a coil? Would the drive shake up something else?(**WestEndAngler & cb5331 that ? is to you too**)

Again y'all ROCK!!!

fresh non ethanol 87 in it now.... dump it?

On the plugs, I've never used the NGK's, but they should be fine. I was more or less trying to make sure that you had actually set the gap and not just put them in right out of the box. Those may or may not be the best plugs for this application, but as long as you used a cross referenced plug and gapped them properly the engine should run fine.

Yeah, the bubbles indicate an air leak. Just making sure you got all your connections tight when you replaced the lines and the filter.

I wouldn't necessarily dump the 87, but I would use premium from here on out. You could add some octane booster to what's already in the tank if you wish. The lower octane can cause detonation, but that does not seem to be the root of your problem right now.

No, driving down the road shouldn't cause a coil to break or be damaged. If it has anything to do with a coil, it is more than likely a short in the wire. Driving down the road should not hurt the motor, but if a wire was rubbing or something it could cause a short. Coils can just go bad for no apparent reason, you can check for spark on both cylinders to rule that out.

With the info you've posted thus far, I'd be looking for a short somewhere like the other guys posted. Possibly an obstruction in the carb? If the boat you bought is the one I think it is, I'm pretty sure it has not had any problems. Were you able to test run it before you bought it?

Are you running on both cylinders?

87 ain't gonna fly in that motor!! 93 octane bro!! Gonna sound like somebody in their with a hammer!!

Check to see if your running on both cylinders.

If not check the 2 little diodes under the black plastic cover

U need to make sure ur choke is stayin stuck on!!!!

Yes both cylinders. What problem signs do I need to look for on the diodes? other then connections?

I've made up my mind gas is going.

choke is not stuck

Possible intake leak?
Doubt if it's the diodes because both cylinders are firing, but it's worth checking. Have to unplug them from the coils to check em. Be aware tho, when they're unhooked you won't be able to shut off the motor with the key or kill switch. Easiest way to shut it off will be to pull the air filter & put your hand over the air intake on the carb.
Another possibility is a bad oil pressure sensor. It's right by the oil filter. Just unplug the wire from it to check it. That wire could also be grounding out on the intake, since it's zip tied to it.

Sent from my Droid because I'm trying to be as cool as you someday.

Heard you fixed the problem.... Replacing the fuel lines probably caused your air leak & a simple tightening of the connections is what fixed it?

Also that screw on top of the carb is your air mixture screw that shouldn't be touched it won't fall out

Yea I thought I had it fixed!!!! FML!!! I took it out, ran it, hauled asssssss and then BOOM..... the fucker just quit. Sounded like it was running on one cylinder. Fuel was blowing out of the air filter... it was nasty. Towed in by a buddy and straight to Lauroville, LA I WENT!!!!! Hoyt has it now and is going to fix whatever I fucked up. Also had him go over entire motor and hull to fix, replace or tighten-up anything that needed it. New fluids, belts, EVERYTHING. I really appreciate everybodies help. Its nice to know I can come here to troubleshoot. Thanks everybody

Nick

Wow fuel out the airfilter must have at least bent a intake valve. Hope the damage is minimal.

Who knows the air fuel mixture was tampered with could have leaned out the motor. Good luck on repairs. Hoyt will fix you up.

Smoked!! All because of a loose hose!! And running 87 regular gas!!

Terry is known for his motivational speaking.

We'll hope for the best man. Hopefully something simple. I don't remember James having any problems with that thing and everything I'd seen about that rig says it was well maintained!

Hoyt will fix it ip for you.

I wonder if those billet push rods caused valve damage???

Just my opinion, but I would suggest taking them out and replacing them with stock push rods.

What rods are they?

I believe billet. At least that's what the ad said but it's not like I could check either the valve issue could potentially be the problem. I remember Hoyt mentioning that when I dropped it off. While we're on the subject of "stock" I've heard stock= low maintenance and reliability and Mods= performance and lots of knowledge and tinkering. What is y'all s opinion on coverting that motor back to stock with exception to the exhaust and how much $$$$ to put it back to normal? Do I leave it alone?

Carbs are really the only thing that may require more maintenance. A cam and/or heads is not gonna require any more maintenance whether they are stock or aftermarket. I would say just wait and see what Hoyt says, then go from there.

BTW - its spelled "Coastal"

Leave that motor alone. Have Hoyt repair it & just check the valves with each oil change. You should be good.

Run a synthetic oil through there... 10W30 and run premium fuels.

i never check my valves either...anyone care to educate us on proper procedure? the initial problem you had could be your spark plug wire arching to your motor. chaffed wire or a cut in the boot can cause this. i had this issue, and apparently it has been an issue with briggs motors. it will run out of the water...but not under a load. hoyt will get you fixed...but keep an eye out for this if it happens again. let us know what happens

There is a video on youtube that explains it pretty well. The link is posted on this website in several different places. Do a search for valves or setting valve lash or something of that nature. It is not very hard. Just don't forget you need to be at 1/4 past TDC on the compression stroke, per briggs.

Does anybody use the search feature anymore? Geez, come on people, it aint rocket science.
viewtopic.php?f=3&t=14147&p=153730&hilit=ring+of+fire#p153730

To be simple there are a couple videos on U-tube that'll help you out with valve lash

Any news?

whats the verdict,,,started having this same problem, only mine will run perfect for i would say an hour or so, then starts acting exactly as u described,,,maybe u can save me some headaches,,?