Hi all - It’s the middle of duck/moose season here in AK and my 09 36 Prodrive Stage 1 with 160hrs is very very ill. The motor was running great all week then the day before we broke camp the power slowly dissipated (basically at full throttle speed and rpms over the course of a half hour from norms of 25 mph at 4000 rpm to 5 mph at 2000 rpm). As rpms began to drop to the lower end (<2,500 rpm) it began to spit and backfire a lot. The motor will run fine in neutral, but as soon as you engage the clutch it drops rpms, backfires a bunch and dies. The only way we got it back to the launch was to get the rpms to about 3500 in neutral, trim the motor so the prop was barely touching the water, and then engage the clutch and putter back at ~ 4mph. So basically, it runs OK with no load, but with a load it bogs down, sputters, backfires a lot, and dies. Any ideas of where to start? Thanks in advance and here are some pics of what we are missing out on.

Pop the valve covers off, turn the motor over by hand, see if you are getting full travel on all the rockers.

Y'all don't have limits up there???

if it will idle sounds like it might be fouled plugs.

Might have dropped a valve!!

It would be making a helluva racket if he dropped a valve.

I dropped a valve one time and it didn't make a noise. Maybe push rod came out maybe um um he'll I don't know I got somebody that does all that for me !! Lol

Sounds like you are firing on one cylinder. Either a push rod came lose or your valve lash got out of wack. Worst case I can see is a flattened love on your cam. Feel both sides of the exhaust where it comes out of the head. If one is substantially cooler than the other that is your problem cylinder. Pop the valve cover and do what cb said

Thanks for all the responces, I'll start testing them out when I get home and let you know what I come up with. Yup, we do have limits here in AK, but they are pretty liberal (10/day; 30 possession). The pic is the result of a couple mornings of hunting minus a bunch that were eaten for breakfast/lunch/dinner. I'll have to post a delicious recipe we came up with this year for duck pancakes!

Saltwater on spark plugs causing it to ground out?

Too much ginger in the boat

It's odd sein all them ducks before plumage

Man I'd start with what CB said then I would check compression

Had this happen before...your plugs are arching to the metal on the motor. The good news is it can be fixed. The bad news is you could have done it on the water with a few wraps of electrical tape, instead of having to limp all the way home. If your running saltwater it will increase the chances of this happening. Run your motor in the dark. Look at both areas where your spark plug boots are, you will prob see the electrical current arching to the motor. Take some heat shrink or electrical tape and cover this area. If its not arching at the boot, follow your plug wires down and look for any sorts of tiny scratches, cuts, etc where the current can arch out to the motor. Often times the area where the plug wires go inside your cowling get pinched or rubbed and they can cause issues there. If you still can't find it, it could be one of your coils grounding out to the motor. Wash them off real good with fresh water and spray down with corrosion x or similar. This should fix the problem. Good luck. Always carry electrical tape.

And report back...I am willing to bet my house that's what the issue is. But if it isn't you could have a bigger problem such as a blown head gasket, in which case you need to check compression on the valves. Let us know...

It could be a number of ignition issues, give it a good check before you go doing compression checks.

I would pull the valve cover off to look at the push rods though

$50 says he fixes it with a wrap of electrical tape. Check your plug wires and boots before you go dicking around with anything else.

Why only 50 bucks now? Your last post said you'd give up your house...

My house is only worth $50. Some of dguidrys people moved in down the street. Brought home values waaayyyy down

Thanks for all the tips. I pulled the valve covers off and found a loose, notably bent, push rod on the upper rocker and almost no push rod movement when rotating the engine on the lower (though the pushrod looks fine on the lower). So, does this mean I smoothed off the lobe on the cam for the exhaust valve?

Assuming I need to replace the cam, am I best off just replacing everthing with stronger parts to withstand the higher pressures from the oversized valves.

This ^

And someone owes somebody $50 or a house

lmao

Son of a bitch....I'm shocked. Glad you figured out the issue, but I'm shocked. I'll mail the house this week. Pm me your address

Marsh chicken when the engine acts up touch the heat sheild. You will know very quickly if it is the plugs

I switched around the push rods and there is no difference in exhaust valve rocker movement. Anything else it could be besides the cam?

Time to order a performance cam!

I think someone has one on here for sale right now

Anyone know the best place to buy Briggs parts for a vertical 36 (I'm going to replace the plug wires just to be safe as they are pretty worn)? Also, any ideas on who best to purshase a beefed up cam?

Thanks for all the help!

http://Www.yardpartswarehouse.com

Or the boatdr


On the cam, depends what you want. Hoyt at gt has a grind, bps sells them (use boatdr if you order a bps), al at pvt has one for mudmotors, and cody at setx can have one ground to your specs.

My 08 briggs motor rounded an exhaust lobe on the port cylinder. That is the time I modded my engine. Who's stage 1 you have? Different people call it different things. I know there was a rash of BAD cams at one time... Mine went bad after a lash adjustment at 93 hours.

Its got IM heads, Mikuni carb, Marshmellow exhaust.

Do I need to do anything with rockers/push rods or should I just stay with stock Briggs? If I should change out the rockers, anyone else besides BPS and PVT sell custom ones? Any advice on which of these would be a better option?

Stock rockers and push rods are fine. Check your valve lash regularly.

Anything else anyone would suggest changing out while I have it open?

bluebill just put heatshrink over the plug wires that should cure the problem. how do your coils look? if you run saltwater and dont flush your engine they can corrode to the point they will go out on you. anytime you run saltwater take a freshwater hose turn the motor over and spray it in the front of the motor for a minute while the engine idles to wash out the coils and get any salt residue off. heat shrink your plug wires and put some plug grease in the boots before you put them back on the plugs. that should cure any arch issues you may have.

Will do. Thanks marsh chicken.