Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

[JGra]

I have a 1968 merc 200 20 hp motor that to me seems to be running out of fuel. After going wide open throttle for about 200 yards it just dies out. With one pump of the fuel bulf it fires right back up. I have tried to adjust the mixture but it does not help. I have noticed that as long as I pump the fuel buld lightly about once every couple of seconds it runs great and does not die. I have already replaced all the tank fittings (tank and motor side), checked the pickup line in the tank, replaced fuel bulb, replaced all the fuel lines, rebuilt the fuel pump. I even took the pump back apart to see if everything looked good. I had the carb apart about 2 monts ago when I first started this project. I did not put a rebuild kit in it. I just gave it a good cleaning and put it back together. Could my problem be in the carb? Bad needle and seat, clogged high speed jet, float problem. Like I said it runs great as long and you pump the bulb while running. I think I have replaced everything in the fuel system that I could think of that would cause this problem. Any help would be very welcome. The motor is in great condition for its age. It idles great and purrs like a kitten but I cant seem to get past this last little bug and its driving me crazy. I spent 25 years as an auto tech for a ford delearship so engines are not new to but. Please help, if its not in the carb the my next option is the 12 Gauge (just kidding).

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Bump (help !!!!!!!!!!)

 

[ENSIGN]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Work on em every day,sounds like its time to rebuild the fuel pump.

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I already have rebuilt the fuel pump and have taken it back apart and everything seems ok with the pump. I am going to go thru the carb once more to make sure everything is ok. If I still have the problem I am going to try and install a low pressure (3-5 PSI) electric fuel pump and see how that does. Remember this is a 15 ft john boat that does more trolling that running on motor. Its not something that runs wide open for hours at a time. Just need to get me from one hole to another.

 

[wlanenga]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

An easy check. The fuel pump requires crankcase pressure to operate. Check to see that the gasket between the carb and the intake is not covering the orifis that allows crankcase pressure to reach the carb.

If not then sounds like it could be an inlet needle or float problem.

 

[Lion hunter]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I doubt that it's a carb problem because it works fine when you get the fuel to the carb. I would start at the tank. Is the pickup tube good. How old id the filter. Is the primer bulb working. IS the tank vent open. My guess would be the fuel pump as well.

 

[Joe_the_boatman]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Put a pressure gauge on the outlet of the fuel pump. Look for at least 3 psi. If you don't have it, it's a pump/line/pickup problem. If you have adequate pressure, then it's a carb problem.

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Wel I just got thru taking the carb apart and gave it another good cleaning. All passages seem clear, took apart and reset the needle and seat and ckecked all the fuel line fittings. Put is all back together and as normal it cranked right back up. I adjusted the mixture and started to bring up the RPM'S on the muff's. It never did cut off but it acks the same way as it has alway done as it is running low on fuel. It mostly does the cutting off when under load on the water. I pulled the 2 lines going to the fuel pump from the power head and the fuel pump is getting good pulse pressure to the fuel pump. Unless ther is something wrong with the fuel pump that a kit is not fixing I am out of answers.I am going to take it out again and see how it does and if the problem is still there I am going to try the low pressure electric fuel pump. I have not been able to find a replacement feul pump for this motor. Has anyone every tried the electric pump?

 

[cbaldy71]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I am having the same problem with my 1982 80hp mercury.....Did you get it fixed....does anyone one have a solution?

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

No I have not got it fixed yet. I am at my wits end with this. I brought this old Jon boat back to life after sitting for the last 15 years and this is the last thing I have to get fixed. I still use it but have to give the fuel bulb a pump while running.

 

[Lion hunter]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Is the timing advancing when you increase the throtlle? There are alot of things that can resemble a motor running out of fuel. If you don't have a pressure gauge you can get a pretty good idea of fuel delivery by pulling the fuel line and cranking the motor. If it spits a pretty good stream it is likely the pump is good. How long did the motor sit before you got it? Somethings the timing mechanism gets stuck and needs to be lubed.

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

The timming mechanism is moving freely. The motor had sat for about 15 years. I have been all thru it and replaced all the wiring, plugs, rebuilt fuel pump and carb, all new fuel lines and fittings from the tank to the carb, Replaced water pump, replace shift seals, replace propshaft seals. The motor idles perfect and runs great wide open for about 200 yards and then acts like it runs out of fuel unless you pump primer bulb while running.

 

[chad4050]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

i would have to say its your fuel pump nothing else

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

That seems to be what everyone says. Problem is the fuel pump is no longer available anywhere, new or used that I can find. That why I was going to go with a low pressure (3-5 psi) electric fuel pump.

 

[cbaldy71]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

That is exactly what mine is doing...i also have all new fuel lines and i even put in a new tank... After about 2-3 hundred yards if it is opened up i loose pressure in the bulb and it wants to die, if you pump it while running, it runs perfect....

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

Same here and its driving me crazy. I just tried one of the suggestions. I took the line off going to the carb and primed the fuel system. I then spun the eng over but was not getting any fuel out of the line. I know these fuel pumps are not mechanical but are what they call pulse pumps that operate of of exhaust pressure(which I do have on both ports). I dont know if it should come out with the line off with this type of fuel pump. I still think the low pressure electric put might be the trick.

 

[fred's]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I?ve been having the same problem with a 1978, 200 20hp
It hadn?t been used for 14 years, now it won?t start at all
I used it a couple of times priming the bulb as we went, just ordered the pump kit, but now I don?t know if I should even bother rebuilding it

 

[JGra]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I would go ahead and rebuild it. There is nothing to it and it might fix your problem. Mine was really bad before I rebuild it. I could not keep it running for any lenght of time. Now it idles great and runs great to about 1/2 throttle. Just need to get past this one problem and the motor should be good to go.

 

[fred's]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I would go ahead and rebuild it. There is nothing to it and it might fix your problem. Mine was really bad before I rebuild it. I could not keep it running for any lenght of time. Now it idles great and runs great to about 1/2 throttle. Just need to get past this one problem and the motor should be good to go.

mine went from smooth to not starting
good luck with yours

 

[Ware5150]

Re: Merc 200 20 hp Running out of fuel PLEASE HELP !!!!!!

I think you might have a small leak somewhere along the fuel line. I have an clear fuel filter and it keep running out of fuel on idle. I used an air compressor 40 psi and found a very small leak by the bulb. Fixed the leak and the filter will stay full for days.

Hope this helps.