Honda 90 EFI Mystery problem

[Spaceman]

100hrs on engs. At above 5000 rpm it sputters and bogs down, usually after 1 1/2 hrs running. 4500 rpm all OK.Clean tank ,clean lines ,new filter (OMC 3214),new gas (unleaded reg), purged all air from lines,new anti-siphon valve to tank.Replaced fuel filter in eng.( before fuel pump).The other eng on port side,not as bad but does the same now and then, Mechanics on Kauai new to this eng. no clue??? I suspect a relay for the EFI system, maybe, re: fuel pressure at high RPM ??? Any help, much appreciated.

 

[hondon]

Re: Honda 90 EFI Mystery problem

It sounds like a fuel pressure issue to me as well so exactly what is that fuel pressure at the exit of the high pressure pump when this unit is not doing what you want it to do?You should see a consistant 40 psi or more.If those numbers are not present start with the high pressure fillter on the vapor separator.Since you are haveing trouble with the kicker as well I gotta think we have a fuel delivery problem here.Are we tee'd off a common water separator?Have we taken a fuel sample and done a sobriety test on it?Try Craig at 808 551 2139.Reccomended by a buddie I attended Honda school with.Good luck and hope I gave you some help.

 

[Spaceman]

Re: Honda 90 EFI Mystery problem

Thanks Hondon-I will forward your theory on fuel pressure to my mechanic. The other eng is the same model ,I have dual 90's and two separate fuel systems,and separate filters for each. I know very little about the EFI system but I thought maybe fuel pressure sensor or something that causes an abrupt and short cut out of fuel at higher RPMs at 3/4 tank on the way home against the wind.

 

[hondon]

Re: Honda 90 EFI Mystery problem

Sorry about the twin mixup.Has this unit been run on an alternate fuel source for each engine ?A six gallon portable tank will work nicely.If the problem go'es away or gets substantially better you have a fuel delivery problem with the boat.Also with twins mounting height can become an issue.Has this boat always been like this or is this new?Have you added any weighty accesories if it has not?Do you have alot of spray coming off of those engines?There is a service bulletin and update on these engines but I am at home and ca'nt recall the # or syptoms.Your dealer should be privy.I'll look it up tommorow and let you know what I find.

 

[Spaceman]

Re: Honda 90 EFI Mystery problem

Hondon ,thanks for your reply again.No ,I haven't tried an alternate fuel tank cuz I'm running charters,3 1/2 hrs ea., twice a day, and it happens on the second trip (usually) on the last bit . The "U.F.O." is a 28' power cat designed and built by me in '88. Same eng height as previous Honda 90s,2 sets in the last 8 years. No weight changes but it is a heavy load as the boat is certified for 15 pass. It has performed fantastically for 20 years in the wild waters of Kauai. No big spray from the engines from wrong trim or height.My distributer has ordered new fuel pumps. I still suspect what you first said , low fuel pressure after the high pressure pump.You can see the boat at <napalitours.com> ALOHA

 

[hondon]

Re: Honda 90 EFI Mystery problem

While your at it,pull out the pickup tubes and inspect/clean the screens that come with them.After 20 years who knows how cruddy they are.Just another thought.ALOHA as well from Humboldt.

 

[Spaceman]

Re: Honda 90 EFI Mystery problem

Thanks Hondon, I inspect all the intakes every year.No prob's there.One thing I don't like on the new EFI's is the fuel line conn. from the eng to my fuel line is a connector stent, instead of the old Honda fuel connector clip. I found a chunk of hose flapping over the stent on the inside. I removed it and thot I solved the prob. Nope ,still the same. The connector stent was installed by the "mechanic" upon installation.NERTZ!

 

[Spaceman]

Re: Honda 90 EFI Mystery problem

FYI Thanks Hondon for your previous advice .I finally solved the problem. Honda re-designed the low pressure fuel pump and the eng's run fine with the new ones.

 

[hondon]

Re: Honda 90 EFI Mystery problem

Thanks for the update.Honda can be awful about letting us techs know about that stuff.These are awesome engines from what I've seen and hope you do well with them.