Merc 150 wont take fuel (UPDATE)!!!

[mellowyellow]

Re: Merc 150 wont take fuel (UPDATE)!!!

wow... thought for sure you had it. thrown out<br />at home plate eh?<br />maybe try a pressure test on the fuel system?<br />try a diff. primer bulb?<br />check the seal on quick connect?

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

I sure appriciate everyone sticking with me on this one, I know we can eventually get this figured out. I have a new fuel pump, but havnt really checked the flow at adle, (need to). I changed the fuel connector, and also had someone push in on the connector while idling around and it didnt help. I havnt changed the bulb either, so I guess that would be another cheap thing to try. The Marine doctor seems to think I should re-jet the idle circuits, at least I can get to them without taking the carbs apart again.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

Ordered jets today, $3.50 X 6. The stock idle jets are 56s, the closest thing next size down is 48s. (yes, thats right, on these carbs you put in smaller jets to richen the Idle). If they are too rich, I can allways drill them out a couple thousands at a time untill I get it right. Man I hope this solves this head ache.

 

[clanton]

Re: Merc 150 wont take fuel (UPDATE)!!!

Some of these engines have different size jets in each carb, depending on location of carb. Have you check the jet sizes against a Merc or Clymer manual.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

This particular engine has the same jets on all carbs, and the same from side to side. They are also the right ones for my elevation. Im rejetting on the advice of several qualified mechanics as a last resort. Every posable base was covered in the last few months. The general concensus seems to be that if it is coughing and sneezing at an Idle while in gear then it is running lean on the low side. We will soon see. The only positive thing about all of this is that I now know my engine from top to bottom, and I know what is new and what is old, (not much is old).

 

[quantumleap]

Re: Merc 150 wont take fuel (UPDATE)!!!

I know this may seem like an obvious question, but you're not running any of that old fuel that you guys are recommending to everyone are you? Old fuel sometimes gives symptoms of a lean-run condition. It seems like you've covered all the other possibilities. Not trying to fan the fire, just trying to help.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

This thread has got quite long, so I guess reading it all would take a while, I think I said that I had removed and cleaned the tank this spring, but might have put that in the Marine Doctor forum. No, no old fuel, not any, and It was doing it even before I put the GTA Fuel enhancer in. I inherited this problem with the boat as I just bought it last fall. I knew it had the problem when I bought it, But I thought it was bad fuel and wouldnt be a major problem. WRONG, I,m beginning to think that this is the reason that he sold it. I bought the boat from a broker, and never talked to the owner. I got it at a decent price and havent really had to put a lot of money into trying to find the problem, only a lot of time. And like I said, It forced me to learn my engine and I know it well now.<br /><br />No problem "fanning the fire", I will take all help. I wont get the jets untill next week, so I wont be able to update untill the end of next week. If the jetting would have been the other way around, I would have just drlled the jets out a little at a time, but with this engine, I guess the idle jets are air jets and I need to restrict them to fatten the mixture.

 

[mellowyellow]

Re: Merc 150 wont take fuel (UPDATE)!!!

in the meantime you may want to pressure test<br />fuel system to look for air leaks LD. 1 small leak<br />in wrong spot can cause it to lean out. shot in <br />dark, but wouldn't be the first time I have seen<br />this as a cause on this forum.... <br />good luck! <br />persistance breaks resistance

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

Here again, been there done that, sprayed starting fluid all around the carbs and intake, no change in RPM, but keep it comeing.<br /><br />Just reread your post, I changed all the fuel lines, fittings that were questionable, and now the bulb. The only thing I havnt done is try and run it on another tank, but I cant imagine what that would prove, the fuel runns free from my built in tank. May try it anyway as I have one I can barrow. I may go fishing this afternoon if is doesnt rain to hard and may try it to see.

 

[mellowyellow]

Re: Merc 150 wont take fuel (UPDATE)!!!

that meathod is only 50/50 LD. u have a way to<br />do a real pressure test?<br />did it ever run properly with current jets?

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

Like I said, I bought the boat this way? Im sure it ran ok at some point in its life. Whats a good way to do a preasure test, Im all ears.

 

[quantumleap]

Re: Merc 150 wont take fuel (UPDATE)!!!

It seems like you have addressed just about every possibility fuel wise. I'd also check possible exhaust leak/restriction as this could cause idle only problem. Good luck.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

I think some are thinking, and I have to agree, that why does the engine all of a sudden need to be rejetted? I know the quality of fuel is not as good as back in 87, but when I first flushed the tank and started to figure this out, I had about 5 gallons of aviation gas I first put in it, it ran the same as it does now even on that, so I do not think it is fuel quality. Its pretty puzzling, I can usually figure stuff like this out but not this time so far.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

Got my jets today, hope it dosnt rain all weekend.

 

[gss036]

Re: Merc 150 wont take fuel (UPDATE)!!!

LubeDude, did the jets make any difference, you have been awful quiet lately.

 

[gss036]

Re: Merc 150 wont take fuel (UPDATE)!!!

I bumped this up last night but somehow it disappeared, so will try again. Curosity kills the cat you know!

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

Havnt had time to mess with it, although Im chomping at the bit to change them though. Rained Saturday, took the Misses for a drive Sunday. Worked in the yard last night after work. Maybe tonight.<br /><br />I have been thinking about the fact that the new jets are 48s, and the ones in there now are 56s. That was the closest I could get to the 56s. Thats eight points. I have thought about drilling them to a 52 to start, but then again if I screw them up, I have to buy new ones again. Six X $3.75.<br /><br />I was thinking last night though, what if this doesnt do it? I have no Idea where to go from here. The only thing I can think of would be to pull everything off, (carbs, intake and reeds) and replace the reeds with Boysen. If I have to do that, It probably wont happen untill winter or next spring.

 

[gss036]

Re: Merc 150 wont take fuel (UPDATE)!!!

Good luck, hope it works out for you. I hear on you the time, ot taking the time. I put on a new SS prop on my 200 Merc last month and still haven't run it. I just went with the same pitch, switched from Alum to SS. I suspect I will lose about 200 rpm off the top end, which is ok as never run up there.

 

[mellowyellow]

Re: Merc 150 wont take fuel (UPDATE)!!!

hi LD, sorry your post got burried and forgotten.<br />I don't have a good answer on best way to do the<br />pressure test as I have never done it myself.<br />why don't you post a new topic and ask around?<br />I can tell you that over the last couple years<br />I have seen 3 or 4 guys with your problem that<br />finally figured out it was a leak from a cracked<br />fitting or something. I also have seen lots of<br />people suggest removing the lil' ball bearing in<br />the quick-connect to improve flow. wish I could<br />be more helpful...<br />good luck,<br />M.Y.

 

[LubeDude]

Re: Merc 150 wont take fuel (UPDATE)!!!

I suppose you could just put a fitting in the fuel line up where the line goes into the carbs and use a bicycle pump to put some preasure on it.<br /><br />I cant believe how many people have been involved in this problem. Not only people here on the forums, but local people. I ran around the lake several times with marine mechanics sitting on the back of the boat and the cover off doing everything from holding there hands over the carbs, pushing in on the fuel connector, looking into the carbs while running, pumping the bulb while trying to accelerate. And amazingly enough for free. Just as a learning experience. Nothing has helped.<br /><br />Now, a really weird thing happened last time I went out, It ran perfectly just one time. It went right throught the RPM range without a glitch, never ever has done it again. Im going to run it on a different tank next time out just for kicks. Ill have the new jets in then so will first try with the built in tank, then if it doesnt work I will try the other tank. I have to say that I am getting tired of it all.