Carb Fire

"I have a BF90 outboard (b

"I have a BF90 outboard (bit older)on a Mexican panga (fishing boat) down in Baja. I had the carbs rebuilt last year by a local mechanic. I took it out last week and the motor stalled on me after a few hours running. No alarms etc. I restarted it and got back to shore (I was thankfully only about .75 miles out). I took off the housing and discovered there had been some type of fire inside the sound dampener that covers the carbs. It looks like the #2 carb (2nd from bottom) had a fuel leak and some kind of blow back ignited it. The dampner had melted and completely closed off the bottom carb intake. Any ideas on what caused this (besides a bad mechanic)? Also, I would love suggestions on where to get cheap carb rebuild kits and a replacement dampener.

Thanks!"

"I had a similar problem on my

"I had a similar problem on my 1997 75HP motor a few years ago. It actually caught on fire after a lean burn backfire. The motor boat had been given a clean bill of health from my local Honda dealer, and I bought it from them. It was on consignment for a customer that was going to buy a more expenssive boat from them. When I got the boat back the dealer, They said that they were very sorry but the motor was 11/2 months out of warrenty an they could do nothing foe me. I saked for estimate for repairs. They told me about twenty five hundred dollars. I said thanks but no thanks. I told them I would do the work my self. They told me that it couldn't be done at home. I asked them if I coild at least get a break on the price for parts and tools. They said that they could not sell the parts at a discount and refused to sell the correct tools (to lock the flywheel). Okay, so I buy/order all parts to replace all that was burned. I overhauled the carbs etc. The choke plate (damper)linkage had meted off. The only way the to replace the linkage is to replace the carb ($400 each). I decided to fixed the throttle plate in the open position permanently. The motor is a little hard to start when cold, but other wise all is good fives later. I hate it when someone try's to tell I cant do it myself!"

RE: "fixed the throttle pl

RE: "fixed the throttle plate in the open position permanently"... ahhhh.. that's the choke plate. If you fixed the throttle wide open you'd run at full speed all the time.
Had a simular experience on a sterndrive. Was once quoted $880 plus a months time to get reverse to work properly. It took me two hours and cost $0.35 (new cotter pin).

"What caused your lean burn ba

"What caused your lean burn backfire? What can be done to avoid it? Where did you get your damper?

I don't have an issue with the dealer as this was sold to me in Mexico. I brought the carbs back with me. Honda has a list of carb parts, so I know I can order them to do the rebuild myself. What worries me is getting the plastic noise damper.

John L."

"Robert,
You are correct I wa

"Robert,
You are correct I was refferring to the choke plate that I fixed open.
John,
The plastic damper you referring to is the intake plenum. Try looking up your motor by serial number
on the boats.net website.
Good Luck,
Nick"

"Thanks for the tip. that is a

"Thanks for the tip. that is a great website.

I am going to replace the plenum and the melted interface to the carbs. However, to be safe, I will also rebuild the carbs. Besides the valve set and gasket kit, is there anything else you suggest I replace/buy to try and ensure I don't experience this again?

In speaking with a dealer yesterday, he suggested that it was either a stuck valve, bad float, or contaminated gas that caused the overflow. Any suggestions on how I can check for any of these? Contamination is unlikely. Water separator and new filter (maybe 4 hours old) were used. The gas had set for a few months but had stabil in it and the carbs were all drained previously.

I currently have the intake manifold and carb assembly off and here in the US (motor is in Mexico still).

I appreciate your help."

"I use my boat in Baja two to

"I use my boat in Baja two to three times a year. The fuel there is of very low quality. The fuel can turn bad inside the fuel bowls quickly. Run the fuel out of the carbs each time you trailer the boat, by disconnecting the fuel line at the motor and letting the engine die. If you are going to store the boat for any length of time, drain the carbs and remove the fuel from the boat completely, maybe transfer the fuel to your tow vehicle. You need to sync the carbs once you get the motor back together. I use the SyncPro by Motion Pro I bought from my local motorcycle shop for about $100.
Good luck, Nick"