Force 125 Hp 1258F8B Consuming gas + more

[MuskyHunterDave]

Hello. . . I have a 1988 Force 125hp that was running fine, and now It only runs up to about 3900 rpm ( not full power) and I am using a gallon of gas a mile.

ANy suggestions as to what this might be ?? Floats ??

Also could someone tell me the factory suggested plugs for this motor, as My manual is in the mail.

It has NGK BP8H-N and 10 under that. These where in it when I bought the boat / motor, and I want to get new ones and want to make sure they are the right ones.

Thanks in advance for the advise / help

 

[Frank Acampora]

Re: Force 125 Hp 1258F8B Consuming gas + more

A stuck open needle and float could cause the engine to run rich and use a lot of gas while not making proper power. You need to pull the plugs and check if they are really wet. While you are at it, check for a good spark on all four and check compression on all cylinders. If compression is high and nearly equal on all cyl, and if you have good spark on all cyl, and if the plugs look very wet and oily or highly carboned, then start checking fuel delivery. Some of those carbs had rubber tipped needles and if the rubber is worn or missing, the needle will not seal, flooding the carb and running the engine extremely rich. Other carbs had a steel needle with a rubber seat--same thing if the seat is worn.

I have the same engine and I use Champion Ul18V. I think the NGK is BUHsomething

 

[MuskyHunterDave]

Re: Force 125 Hp 1258F8B Consuming gas + more

Hello. . .

Checked the compression & 147 - 148 on all (with all plugs in and out)

Good Spark on all as well

FLoat needles are rubber tipped . . .

The top carb was overflowing when primed, so I reset the float to stop that, but I will need to get some new float needles.

You mentioed you have the same motor, you wouldn't happen to know the part Number for the float needles would you ??

Irronically the bottom two plugs where wet, and the top two not, but it was the top float that was not shutting down and leaking ?? HMMM

One more thing, you said you used a " Champion Ul18V " Plug is that a UL18V ? Wasn't sure if it was an L or an I

DO you know the gap on the plugs ?? Thansk again for the info !!!

 

[Frank Acampora]

Re: Force 125 Hp 1258F8B Consuming gas + more

Plug is UL18V. It is a surface gap plug. You don't set them. Just install.

I don't know part numbers but I think you need to order a whole carb rebuild kit. I don't think they sell the needles separately. If the rubber tips look good, you may not need to replace them. sometimes crap sticks in the seats and prevents full closure. Clean them out and you're ok to go.

BTW, to set the float, you invert the carb, and adjust the float until it is level with the casting. The manual gives a number of 13/32 but if you set it level, you will be real close.

 

[MuskyHunterDave]

Re: Force 125 Hp 1258F8B Consuming gas + more

Thanks for the info, and FYI . . . I talked with a local mechanc (been around a long time), an he said napa carries the Float Needles for the 120 which is the same as the 125 - under part # 18-7057 and they are about $9.00 so a guy doesn't have to buy the whole carb kit @ $49.00 X2 ( price quoted to order out of local shop) when the rubber tipped needle, it seems to me, is really all one would need (it Wears First)

I am headed to napa this afternoon for the plugs and I will pull and take one of the needles to see if they are the right ones, so I will let you know how it works out. Good piece of info if it pans out

 

[Bry21317]

Re: Force 125 Hp 1258F8B Consuming gas + more

I had the same motor on my old boat, that I had for 11 years. I was always told on here to run the NGK BUHW plugs. They were the very best for that motor.

Thats all I ever ran in it. You really want to wake that thing up some, get some Boyeson reeds and put them in there, I did on mine and it made a world of difference.

 

[CharlieB]

Re: Force 125 Hp 1258F8B Consuming gas + more

Also check the fuel pump diaphragm to be sure that it is not leaking fuel into the cylinder providing the vaccuum pulse. It will also cause reduced fuel milage, a reduced WOT RPM and 'wet' the one plug.

 

[MuskyHunterDave]

Re: Force 125 Hp 1258F8B Consuming gas + more

Alright I went and got the NGK plugs, and looked at the Float needle at napa I mentioned the local mechanic said should work, but it is not the same, so disregaurd that piece of info.

I did reset the floats and they are seating good, but now I have another issue.

Where the throttle linkage advances the timing there is an adjustment just under the flywheel which is a threaded plastic block with a piece of allthread & lock nut that advances the timeing as you throttle up (right?). I saw that the plastic piece the adjuster goes through had a crack in it, so I removed it and repaired it, but I now need to know How to readjust the timing advance once I reinstall the adjuster.

I was also curious (in the event I need to) is there a start point when adjusting the carbs ?? Say all the way in and 3 turns out ?? or ??

Is there somewhere online with service manual info on this engine, as I am waiting for a manual to arrive.

Thanks a lot for all the advice

 

[MuskyHunterDave]

Re: Force 125 Hp 1258F8B Consuming gas + more

Hello. . .. .
I checked the float needles, and they do seem to be seating, for when I squeeze the fuel prime bulb it susptains pressure.

I have not been able to take it back to the lake yet, but am planning on it in the next two days or so, but I was curious, in the event it is still consuming fuel at high rates, is there an easy way to diferentaite fuel consumtion between either the fuel pump diaphram or the float needle as the culprite of the issue, or is it just replace and see if improvement results ??

A pin hole in the pump diaphram would not be visually evident, and other then putting pressure to the float needles with the prime bulb is there other ways to check these possible issues ??

Thansk for all the advice !!!

 

[MuskyHunterDave]

Re: Force 125 Hp 1258F8B Consuming gas + more

Hello. . . .
Well . . . . I pulled the fuel pump, and could not see any holes, but there was gas on the back side of the diaphram, not sure if it seeped through removing, but I will replace the diaphram as it seems to be the lower carb having the issue which is the pusle feed for the fuel pump - RIGHT ?, so that makes sense I guess that it would be the culprit for sucking up the gas and making it run under power ????

Can I re-use the gasket if it looks good, and does the diaphram glue to the gasket or is it just held by pressure after tightening ??

Thanks for all the help !!!!