5.0 tbi mercruiser trouble

[opietoo]

Hi I am working on a 2000 mercruiser with a tbi 5.0, the engine is laboring when we try to bring it up to full throttle. We have replaced everything on the ignition system except the plug wires. Also everything on the fuel system has been replaced except for the fuel pump, and the fuel pump is putting out 70psi at the back of the throttle body with mechanical gauge. Talked to mercury techs and they said that the fuel cooler may have been frozen and causing a restriction, replaced the cooler to no avail. We are at wits end any help would be greatly appreciated thanks in advance.

 

[Fun Times]

Re: 5.0 tbi mercruiser trouble

As you know 70 PSI is way to high, so yes you most likely would think to have a restriction that is usually on the fuel return side. But you can't just rule out the pump either as it could produce high pressure as it's been done before.

Guessing while you were in there, you did a new fuel pressure regulator and just as important a new filter screen that sits under the fuel pressure regulator item number 16, http://www.mercruiserparts.com/Show...=4856&bnbr=90&bdesc=Fuel+Pump+And+Fuel+Cooler ?

Check the hoses between the fuel filter and the fuel pressure regulator for kinks, etc. etc. Also you may want to remove them to try and inspect the insides of the hoses the best you can for deterioration. Also check all the brass fittings for a restriction at both the filter assembly and cool fuel assembly. Item numbers 6 & 19 at the cool fuel assembly in the link above.

Check Item numbers 1, 14, 13, 5, 6,
http://www.mercruiserparts.com/Show...4154.png&inbr=4856&bnbr=110&bdesc=Fuel+Filter

Also check your spark plugs, with 70 PSI they should be a in a fouled condition.

 

[alldodge]

Re: 5.0 tbi mercruiser trouble

Could use a bit more info, you said it is a 5.0 tbi but what year. An engine seril number could help if you have it a bunch. What type and size boat is it in? When it does come up running does it reach maximum WOT? The tbi engines I can find have carbs and 70 psi is way to much, is this an EFI engine?