Hello, we have a 1999 Honda BF90 4 stroke with a very frustrating problem. Cold start is fine. But warm starts are problematic. Makes the motor undependable and has put us in danger twice.The problem happens after running the BF90 some miles and then shutting it off to either troll around with a 8hp or anchor up.When you attempt to start it - it turns over, sputters just slightly and that's it. Cranking more it just spins, no pop. Seems like it's not getting fuel. Originally, because of the initial pop I thought I was flooding the engine but I don't think so.I was told to disconnect the fuel line from the 90hp if we were going to troll ahwile, to stop the vacuum of the trolling motor from sucking the fuel back out of the 90. The last time we had this problem we forgot to disconnect. (The two motors share a common fuel line, that goes to a T-fitting, where it is split into a fuel line for each motor. Each motor's line has a fuel bulb in it.)We did however, pump up the fuel bulb of the 90 real good before trying to start it.Generally if we wait 15 - 30 minutes after the initial starting failure, and after considerable cranking we can get the 90 to start. Any ideas?Can some sort of vacuum lock be created if the trolling motor did suck the fuel out of the 90?Really look forward to your ideas!PS. of course the dealer has had the motor back a number of times and can't diagnose a problem.
all major motor motor makers recomend either seperate suply lines all the way back to the tank or a three way selector valve but i dont think this is your starting problem . i have had the same problem on two diferent motors one 2 hp one 50 hp hondas both motors had intake valves that where too teight check the valve lash adjustment this may be your problem
Frank is right on both counts.This thing should ideally have a separate fuel source for the kicker or a way to isolate the engines like a gate valve at the water separator that I hope you also have.Valve adjustment is part of your regular maintainance and should be done every 100 hours.These valves get tighter as they wear and a tight exhaust valve will cause your exact symptoms.Hard starting warm.
Thank you very much OMCFrank and Hondon, in nearly three years no one has suggested that possible problem. Thanks too for suggesting - 'gate valve at the water separator' to isolate the supply lines. I'll check the marine store today. Thanks again for taking the time to reply!
I have had simular problems with my Merc 850. It starts fine cold, but when the motor is warm it is difficult to start. Could the tight valve be the problem on a Mercury?If so, could you elaborate on how I can adjust the value? I have minimal outboard maintenance knowledge.Thanks