Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

[dtigner]

My 1984 MERC. 140 3.0L Ran great up untill the other day when I noticed no fuel was getting to the carb. It uses a Carter LOW Volume mechanical fuel pump . I assume the crank shaft it runs off of is worn out in that area because a new pump won't even work!Any ideas? someone told me to convert it to a electric fuel pump ? Is this possiable? or another pump with a longer rocker arm??Thanks for any info.

 

[Trent]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

If the lob on the camshaft for your fuelpump is that bad that it will not pump fuel, get ready for the rest of the lobes to be bad also. Time for an overhaul of the engine. Yea you could install a electric fuel pump, But your not taking care of the real problem. Wear.

 

[a.d.mobile]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

This is a wild one been doing this a long time and have never seen a 140 with worn lobe. if it was running good why are you looking at the pump? how do you notice no fuel? are you looking at the yellow hose? fuel does not get to the carb form this line. lets get some more info. did boat die out, loss of pwr on high end, no start. have you done a volume test or pressure test? let us know!

 

[dtigner]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

I'm not looking at the other line attached to the carb. The boat Ran real good and I have a inline clear filter on the fuel line.It used to run full pressure then I started to notice the line starving for fuel about half full in glass filter that was put inline.When on the water if I throttle up I can actually see the fuel suck dry in the line and right after that the engine surges hard (2500-3000rpm),put in nuetral for about 30 sec. and I can see fuel start to replenish in the line again. I bought A NEW pump and it did the same thing.The shop told me the pumps were fine.I had the carb rebuilt and nothing changed . Idle is about all it will do ,throttle up, gas line runs dry. I thought the throttle kill switch was giving me the prob. but not after bypassing it and checking the position not to mention the obvious fuel disappearing and not staying pressured.I think my cam is worn so that why I looking for another way to get my fuel to the carb. 4-6 lbs of pressure shouldn't be that hard to get ,one would think....

 

[Rockyncali]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

I would have to agree with A.D. and say I've never seen a fuel pump lobe go bad. Maybe, a lifter lobe if it was preloaded wrong but NEVER have I seen a pump lobe. An electric pump is an nice upgrade but like trent said "you're not taking care of the problem". IF you need to change it. A couple of things you have to watch out for is 1. if you run the gas low you can cause damage to an electric pump. I've seen an electric die after only 1 time of running out of gas. It requires the fuel as a lube, so, no fuel no lube= burnt pump= more money. 2. Electrics require 12 volts or more of power and a very good ground. Since most power boats are fiberglass a ground is hard to find so it's very important that it be wired very well. Also the bumping on the water can easily turn a good ground into a fire hazard. So again, bad ground= burnt pump= more money. So what ever you do make sure you really need to change the pump and if you do, make sure it's done correctly.

 

[jlshields]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

blue, did you check to make sure the fuel pickup in the tank wasn't clogged? Or that the anti-siphon valve wasn't stuck closed?<br />Rocky, maintaining a good ground isn't hard to do. Everything 12V requires a good ground. You can always find a good ground at the engine block or negative battery post.

 

[dtigner]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

I made sure no clogging was happening in the tank, I actually had a NEW 27 GAL aluminum tank installed and all new lines comming out so I even double checked them just incase of a pinched line or something.I was able to easily siphon gas right from the main line. No restrictions there.Maybe I have a FREAK case but it still seems like some trouble with the lobe area. The engine ran strong,tested comp. @130 all cylinders,and even ran great speed sprints @5000+RPM wide open.Oil was changed and no metal or particals came out...the strange part is I could see the strike marks on the old pump on the rocker arm and the new pump about the same mark points but not as harsh though.I think I might try a electric inline fuel pump.And just cap off the old spot where the pump mounted.I just wasn't for sure if many people do this on a boat engine???(For a engine pushing on 20+ yrs old and running this good I hate to tear it down) .But if the electric pump is installed right what will it hurt?

 

[DHPMARINE]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

blue... Seems like you are covering all he bases,but I also doubt it is a bad cam.Think about it,the problem occured suddenly.For a cam not to activate the pump,about 3/8 or more of the lobe has to dissapear suddenly.Get a portable tank,and substitue it.Then work from there.Have you checked to see if the tank vent is clogged,or the line twisted?<br />DHP

 

[a.d.mobile]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

try what dhp is talking about use a portable tank from a outboard with primmer line when boat acts up squeaze the baulb and see if you can change the problem. 5000 rpm thats a tad high for a 3.0????or am i wrong????

 

[Capt Ken]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

Now this may be a long shot but be sure someone hasn't put a PCV valve in the valve cover. Seen this happen before and it pressurizes the crankcase and caused the fuel pump diaphram not to pump. The fuel pump is open internally to the crankcase.

 

[a.d.mobile]

Re: Crankshaft worn ,MEC.Fuel pump won't work..ANY CONVERSION??

well PERL keep us updated hard to fix when we are talking to ourselves!