New Mariah Owner with questions!
 

Hello to all,

I have just bought a 1991 Mariah MX 19. It has a 4.3L mercruiser V6. I cannot keep it running above 3000 RPM without it dying out. I have replaced the fuel filter, cleaned the carb and the main fuel in fitting on the carb. I have replaced spark plugs, wires, distributor cap and rotor. Cannot seem to put my finger on it at this time. I am begging for help. Its almost boating season!! lol. Thank you to anyone who has some insight for me.

Re: New Mariah Owner with questions!
 

when it dies, have you pulled a plug to see if they are wet or dry ?

If wet, your loosing spark, if dry, your running out of fuel. Id look at the fuel line to the tank

Re: New Mariah Owner with questions!
 

Assuming you have done the fuel filter/carb/small filter at the carb inlet/distributor/fresh fuel etc.....then its time to change the fuel pump. It can't keep up with the demand of the engine.

Re: New Mariah Owner with questions!
 

Thanks guys

I did do the fuel filter, carb, carb inlet, plugs, wires, cap, and rotor. I was guessing my next best bet was the pump its self. Going to be doing a pressure check on that here soon. I will let ya'll know what I come up with. Thanks for the help. very much appreciated.

Re: New Mariah Owner with questions!
 

Pressure guage on the out line and vacuum guage on the suction side will tell the tale on the pump. If the vacuum is too high on the suction side you will get inadequate fuel volume when the engine demands it even if you have adequate pressure under idle or no load conditions. Mikeyt sounds like he is right on target and I think I'm getting too far ahead of the testing. The reason I mention it is because I ran into a fuel problem two weeks ago where there was a restriction in the suction line that only caused a problem under high engine loads.

Fuel pump priming??
 

I posted yesterday about my 4.3L Mercruiser not staying running at about 3000RPM. I took advice and replaced the fuel pump. Now...obviously it has to prime. Is there a certain way to prime it or do you just give it hell until it primes itself? We are watching the carb and we get a good spray for a minute and than nothing. I'm guessing it is just working the air out of the lines but am not sure. We are getting a better spray than yesterday with the old pump. Its just on and off at this point. Just wanted to see if anyone had suggestions or if I should just keep turning it over til it primes itself. Any advice would be appreciated. Thanks

Re: Fuel pump priming??
 

Have you checked the fuel strainer in the carb? (part 4 in the attachment)

Re: Fuel pump priming??
 

Thanks..That worked but......I just recently cleaned that a couple days ago. Any suggestions how to get that crud out of the tank with a full tank??

Re: Fuel pump priming??
 

What Andy B said! That was one of the things (small filter at carb inlet) i mentioned in my earlier post.

Re: New Mariah Owner with questions!
 

You guys are very helpful!! It worked for now will have to keep checking that if I have problems.