Trojan Boat Forum

Thanks for all the replies to my earlier post on electronic ignition.

I've got a 76 F25 with the 318. I was having starting issues, that looked like they have been resolved. I replaced the ignition module, ballast resistor, spark plugs and had the carb rebuilt. The engine now starts up everytime with no issues and idles ok, however will die when in gear and given a load.


I've played with the settings on the carb and think I've probably messed with it too much. Is there a "standard" set of settings that I could use on the screws on the carb? i.e. left screw 1.5 turns etc... I'm stumped... it's a carter 4bbl

_ update: In idle now, even in neutral, it will bog, sounds like too much fuel or not enough and die out. really stumped... . any help to diagnose would be appreciated...

When you say you look in the carb and fuel is squirting good, do you mean you see fuel squirting into the throat of the carb from the boosters at idle? I don't think you should see fuel coming through there at idle unless you're under load. Those are off idle circuits. At idle no load, I think fuel should be coming through the idle ports only which are below the throttle plates.

You should be able to start with 2 turns out. Warm engine to operating temp and adjust for best idle while you count the turns you make. Try a quarter turn at a time to begin, then fine tune from there. Remember that it takes a while for the new adjustment to settle so you must be patient after an adjustment. If you're more than 2 1/2 turns out, I think you're too far and will be too lean. You're not opening up a hole to let more fuel through, the screw changes the vacuum in the circuit which dictates how much fuel will flow. Adjustments to idle speed must be made as well.

Carter AFB? Do the idel mix adjustment screw sin front still turn? They often freeze upon boats.

Big D is close with 2 turns out to start ... if it dies under load, its probablye lean.

If you SEE feul, then its probably rich, so start from a standrad 1.5-2 turns out.

There are a lot of good references on the web on how to set up your AFB/318 ...

Be careful with the flame arrestor off and all that fuel ...

Good point on the arrestor Ross. Ventilate, ventilate.

Thanks very much for the replies...It's very strange... he boat never ever started so good, but now just won't hold an idle and will bog out... I think it's a fuel delivery issue, as when I put a load on it, it will stumble sometimes and then catch and then sound like it gets flooded or something, and then other times will just die when I try and put a load on it. I'm going to change the inline fuel filter today and see if that makes a difference.

I noticed another metal filter looking thing from the gas tank to the engine that says fram on it it. I'm wondering how to open that up to see if that's clogged as well... So close to getting it out on the water, and am frustrated as we fix one thing to find another issue. getting closer though...

I have adjusted my 4bbl a few times. Best to turn both screws all the way in and then back them out as advised 1-1/2 turns. This should be done after the engine is warmed up. After this initial setting you want to adjust the screws so your idle speed in neutral should be around 750 - 800 rpm and in gear about 550-650 rpm. Obviously it helps if you have a meter, but I've used the tach on the dash and it's been ok. Also helps if you have someone up top who can tell you what's going on. You can adjust the idle speed screw (the one that adjusts the rocker cam on the side of the carb and joined to the throttle linkage) after you're satisfied with the carb settings. Do all this at the dock and yes be sure that flame arrestor is back on when you're don.

"another metal filter looking thing from the gas tank to the engine that says fram on it" is your FUEL FILTER.

Change it (spin on/off) - or empty it and refill with fresh fuel - its probably full of water, since our lovely gov't mandates ethanol to increase water absorption, reduce mileage/efficiency, reduce reliability and increase the price of corn in our country.

Just to clarify a bit on what was just said. You may have a cutoff switch just before the filter assembly. If you do turn in so its perpendicular to the fuel line (off). Then use a filter wrench to carefully remove the spinoff filter. Pour the contents into a clear glass or plastic jar. If there is water in the gas you'll see it floating on the bottom of the jar. The more water in the filter the more water in the gas, that's what these things are designed to do....capture water in the gas. To replace the filter, put a small amount of oil on the gasket and hand tighten, then tighten another 1/2 turn with the wrench. Replacement filters are available from any marine supply outlet. I keep a few on hand on the boat and replace them every season. Remember to close the cutoff switch before you try to start the engine.

It sounds like you are getting fuel to the carb, however. In my experience if there was too much water in the gas the engine would not start at all and the tank would have to have the water drained from the bottom.

Another area to check would be the fuel pump. If it's starting to fail it might not be able to keep up enough flow under load.

Thanks again for all the help...

I couldn't get that metal filter thing off, there's what looks like a nut on the bottom of it, and tried that as well, but nothing happend... mind you I didn't want to yank to hard as this is all new...any tips on removing it? So your saying there some sort of filter in the metal canister? I was thinking of bypassing this with some rubber hose...

There was another in-line fuel filter just before the carb, I replaced that with a new one... $3 part... and it's running great now... go figure... Had it out on the lake just now with the family for the first time... It's exhilarating yet at the same time a little frightening... just got to get used to it...

I'll try and have another go at that Fram metal container unit but got to say it's running great right now, engine's not shaking or anything...other than for the weeds on the shaft...

Thanks for all the support... Gotta build a bench now in the back for the family to sit on...

The filters have a filter element inside. I've seen some that have a plug in the bottom to drain water; on these, the metal housing is unscrewed to replace the element. On others, the nut at the bottom goes right through and is what fastens the canister to the housing.

The weeds on the shaft can cause the vibration, believe it or not. Try to get them off and see how it performs. Agree on removal of the fuel/water filter canister.

After you replaced all of the ignition components, did you check the ignition timing? If not it might be a good idea.

if its the fram filter housing like this. i have these on my f32, then you need to remove the center top bolt on it and the bottom section will come right off. the filter is listed on the website you might can find them cheaper. i found the last ones on ebay

http://www.boatbandit.com/fram-gaswater ... -4908.aspx

That's the one... OK. I'll try that tonight, there is a large Bolt in the middle of it. I'll see if I can get a replacement at a marina on the way home.

Gotta say, the boat is running great and am really looking forward to becoming a better boater... Docking can be tough...

Had another question regarding the Blower on the F25. I've got fiberglass everywhere and it seems that the lines in the bilge run to the side vents, but don't know how I can access the blower as it doesn't seem to work? Can I just purchase another one and scab it into the system somewhere? Will the existing one vent it out?