1996 Mercury 2stroke 150

[bellavistabassman23]

I got a 1996 Mercury 150 EFI that was sputtering and cutting out. I took it to the shop and they replaced the fuel lines in the motor that were cracked and ran a new line from the fuel tank straight into the motor. Before I was having problems with air getting into the lines and the fuel was draining back into the tank. Now the lines stay primed and runs alot better but it is still cutting out and sputtering but 70% less then before. I definitely won't take it back to the shop that did the last work ( they are very unorganized) I would like to see if you guys could diagnose my problem and put me in the right direction on what the problem could be. Could this be an electric problem with the computer or what?

 

[galamb]

Cuts out or sputters at "any" rpm? just high rpms, while idling?

At this point there are dozens of potential issues.

If you had a problem with the gas lines you may have clogged injectors. Your low pressure fuel pump could have a toasted diaphragm (if your lines were rotted/cracked, the rubber in the fuel pump may have suffered the same fate). Your high pressure fuel pump may be on it's last legs.

It could be ignition related - could have cracked coils, bad plug wires, bad spark plugs, a stator or trigger with issues.

Could also be a gasket/seal problem - sucking in extra air or allowing fuel to escape from the crankcase.

Did they run a diagnostic on the engine computer when you had it in? There are a number of sensors on top of the computer itself that could be the issue.

At this point you start trouble shooting the "easiest" stuff first - but without a diagnostic you could spend a great deal of time checking "stuff you can see" when it could be a simple as a toasted sensor (which you can't see is malfunctioning).

Once you get away from a carburated motor with a basic ignition system, figuring out "what is wrong" is sometime beyond what you can do in your driveway with a screwdriver and a multi-meter - that's just the cost of "advanced technology"....

 

[bellavistabassman23]

It cuts out starting out and on the high end towards top speed. They rebuilt the fuel pump and I personally put new plugs in it. They didn't do a computer diagnosis, I don't think they have one. Should I take it in somewhere and have them put it on a computer? Not really sure what my next step should be but I don't want it to be an expensive wrong one.

 

[faztbullet]

This motor does not store codes so save your $$$. If its cutting out its either a ignition or fuel issue such as a injector. If the injectors have not been cleaned in the last 3 years I suggest doing so. Remove and send them to Brucato along with ECU to be cleaned ,flowed,balanced and ECU tested. All is DIY and around $200. Refrain from using as if lean you can score a cylinder. Is the engine overcharging ??? If so this can overheat fuel pump and make ECU act goofy and the sensors/ignition can be tested with a meter and DVA adapter. Usually EfI motor problems are fuel pressure/ignition/voltage related,vary rarely failed gaskets and such. If I was inspecting your engine I would troubleshoot it as follows: 1) compression test.2)visual inspection of rect/regulators for burnt connection. 3) spark test.4) running voltage test(charging system).5) fuel pressure test.6) change water separating filter.7)running DVA test of stator outputs. If no problems found would follow up with WOT running load test and use timing light to find the missing cylinder,check the max charging voltage and fuel pressure.