yammi f150 fuel probs?

[alaska_racer9974]

i have a 2004 yamaha fourstroke 150 outboard. I had an encounter with some iffy gas the day i took it out of the water last season. i went to put it down this year after flushing the lines out with new gas, and it would still run with a rough idle, and would not rev past 2.5k at full throttle while backfiring. I changed the plugs, the bottom plug was black, the 2,3,4 plugs were white, the plugs are brand new with less then 15 minutes on them. compression is even on all cylinders. I pulled the injectors twice, and everytime i would spray them out, the motor would run fine for a couple minutes then run like crap again. I flushed the vst both times as well. what did i miss? i just put some injector cleaning in the fuel, but it did not seem to do much.

 

[alaska_racer9974]

Re: yammi f150 fuel probs?

After taking the injectors off once again today and blowing them out with air and some cleaner, it did the usual thing of running great for a couple minutes then back to running with a rough idle with backfiring and not over 2.5k rpm at wfo.

My friend suggested the fuel pump may be dirty and not pushing enough pressure, if it is, how could it be running great when i put the injectors back on, and then running crappy later on.

I also bought a fuel injector and fuel system cleaner, do i just put it in the tank, run it for awhile and hope for the best?

 

[JUSTINTIME]

Re: yammi f150 fuel probs?

i would get a aux tank and do a shock treatment of ring-free

 

[Paulk]

Re: yammi f150 fuel probs?

Did you solve the problem? Sounds like my current issue. Thanks

 

[Woodnaut]

Re: yammi f150 fuel probs?

I have experienced some similar problems with my 2006 Yamaha 90 HP four stroke. There are two problems that I have encountered that might give you a hint with your engine:

1) These Yamahas frequently have an inline fuel filter between the low pressure fuel pump and the vapor canister. This is a very fine filter and can plug up easily. Back-flowing through it will usually remove most debris. If you back flow through it, I suggest that you flow into a glass jar so you can verify that in fact some junk came out of the filter. You can remove the filter from the engine and place it in a fuel line downstream of your primer bulb. Flow some fuel through it and and into the jar and you'll find out pretty quick if it was full of trash. These same filters usually have a flow direction arrow somewhere on the outside, so be sure it is installed in the proper direction after you have flushed through it. A plugged filter will limit the maximum rate of fuel going to the vapor canister. The net result is that the engine will start and run great, but then as the vapor canister gets low on fuel, the engine will run horrible because it is starved for fuel. I've encountered this problem twice.

2) Several fuel problems during the past year or two can be attributed to the recent addition of ethanol in gasoline. (I know a serviceman who refers to it as the "ethanol flu".) Ethanol is excellent at absorbing water.

I have thoroughly cleaned out my fuel tanks, lines, pump(s), vapor canister and injectors. Additionally, I had to replace some so-called "ethanol resistant" fuel hoses (the gray ones) with some fuel line that I KNOW is ethanol resistant. Right now, I am relocating my fuel tank vent to a location on the boat that is much less likely to encounter water spary when zooming around offshore or even trailering on a rainy day.

Be sure you have a high quality 10 micron water separating fuel filter in the line between your tank and engine. Whenever you change it, dump the contents of the old filter into a glass jar so you can see what sort of gunk is trying to make its way to your engine. Change this filter often until you can verify you've got a tank full of good clean fuel. I recommend the Yamaha MAR-FUELF-1L-TR even though the Sierra 18-7866 seems to be the same thing.

I pulled the tank level sending unit off of my fuel tanks so I could look inside at the bottom of the tank. I managed to drop in a copper tube at the lowest point of the tank and siphon out the little bit of debris that was present.

My bottom line suggestion is to take extreme measures in making sure your fuel system gets clean and stays clean from the filler cap to the injectors. My Yamaha F90 runs excellent - but only when it has clean fuel. A little water in today's ethanol-bearing gasoline seems to be like poison to these engines.

Best of luck sorting this out - Woodnaut.

 

[yamamarinetech40]

Re: yammi f150 fuel probs?

This may sound stupid, but I would check the vacuum from just in front of the fuel filter on engine....vac. should be 2" or less at idle...and just let it run those two minutes and see what the vac. does as it dies...this sounds a LOT like a plugged vent on tank or fuel restriction....

 

[reelestate64]

Re: yammi f150 fuel probs?

Hi Woodnaut,
How do you backflow as you suggested below. I took my boat in and they wouldn't even look at it for 10 days so I need to try and get it going myself. I am having this exact problem. Thanks. Brad

I have experienced some similar problems with my 2006 Yamaha 90 HP four stroke. There are two problems that I have encountered that might give you a hint with your engine:

1) These Yamahas frequently have an inline fuel filter between the low pressure fuel pump and the vapor canister. This is a very fine filter and can plug up easily. Back-flowing through it will usually remove most debris. If you back flow through it, I suggest that you flow into a glass jar so you can verify that in fact some junk came out of the filter. You can remove the filter from the engine and place it in a fuel line downstream of your primer bulb. Flow some fuel through it and and into the jar and you'll find out pretty quick if it was full of trash. These same filters usually have a flow direction arrow somewhere on the outside, so be sure it is installed in the proper direction after you have flushed through it. A plugged filter will limit the maximum rate of fuel going to the vapor canister. The net result is that the engine will start and run great, but then as the vapor canister gets low on fuel, the engine will run horrible because it is starved for fuel. I've encountered this problem twice.

2) Several fuel problems during the past year or two can be attributed to the recent addition of ethanol in gasoline. (I know a serviceman who refers to it as the "ethanol flu".) Ethanol is excellent at absorbing water.

I have thoroughly cleaned out my fuel tanks, lines, pump(s), vapor canister and injectors. Additionally, I had to replace some so-called "ethanol resistant" fuel hoses (the gray ones) with some fuel line that I KNOW is ethanol resistant. Right now, I am relocating my fuel tank vent to a location on the boat that is much less likely to encounter water spary when zooming around offshore or even trailering on a rainy day.

Be sure you have a high quality 10 micron water separating fuel filter in the line between your tank and engine. Whenever you change it, dump the contents of the old filter into a glass jar so you can see what sort of gunk is trying to make its way to your engine. Change this filter often until you can verify you've got a tank full of good clean fuel. I recommend the Yamaha MAR-FUELF-1L-TR even though the Sierra 18-7866 seems to be the same thing.

I pulled the tank level sending unit off of my fuel tanks so I could look inside at the bottom of the tank. I managed to drop in a copper tube at the lowest point of the tank and siphon out the little bit of debris that was present.

My bottom line suggestion is to take extreme measures in making sure your fuel system gets clean and stays clean from the filler cap to the injectors. My Yamaha F90 runs excellent - but only when it has clean fuel. A little water in today's ethanol-bearing gasoline seems to be like poison to these engines.

Best of luck sorting this out - Woodnaut.

 

[alaska_racer9974]

Re: yammi f150 fuel probs?

I figured out the problem, I realize it is a old post but I just realized I had about 6 private messages from members that were wondering what was wrong. The fuel injectors have a really fine filter on the fuel rail side, I just had to wipe those clean with a paper towel (lots of gunk was built up) then blow them out after soaking with injector safe solvent. Ran like a champ after that.