1996 Volvo penta 5.0 engine issues

[mhinz000]

1996 carver 310 with dual volvo penta (ford)5.0 engines. at the beginning of the season we were having issues with the engines running rough while cruising. would get up on plane and eventually start bogging down. the engine sync gauge would go one way or the other and then eventually stall one or both of the engines while putting thru the marina. after going thru some maintenance items, cleaned the air filter, checked the plugs(ok), cap and rotor were toast replaced that. one of the coils tips was rusty and corroded replaced with an oreilly brand coil and seemed to work fine for a little while but ended up getting a DOA coil. replaced with another one and that seemed to work but then more issues started arising later on once it got warmed up and on plane again. bogging down while up on plane. at one point i was thinking there was a fuel issue because we were doing some hard banking left and right and would nearly stall but then swapped in an original coil and could not get that specific issue to repeat. i believe the coils still may be an issue and plan on replacing with motorcraft ones and still need to check the fuel filters for contaminants. had a thought that potentially the ignition control modules for each engine might be causing an issue once they get hot but i have no codes stored in the pcm. im no expert on obd1/eec diagnostics vehicles/engines. any of your help and wisdom would be much appreciated.

[km1125]

RE " would get up on plane and eventually start bogging down" is most frequently a fuel delivery problem.

"still need to check the fuel filters for contaminants"... that should have been the FIRST thing that was checked/changed. You should ALWAYS carry a spare set of fuel filters onboard, because you never know when you might get a bunch of "gunk" in them and if you have a set you can be on your way quickly, whereas if you don't then first you have to even locate a PLACE to get the replacement filters and then acquire them and put them on. That could ruin a whole weekend where you could have been out on the water!!

Not sure which ECU those engines use. Might post up a picture of it and somebody might be able to identify. If it's an MEFI then you can read codes from it pretty easy just by hooking an LED up to the diag connector. However, there are many issues (like plugged fuel filters) that won't show up as a code in the ECU, so don't expect much. If the symptoms are happening to both engines I doubt it's an ECU or a sensor issue.

[tomschauer]

As KM says, very good chance it's a fuel issue.
Also, you may want to make certain what engines you have when sourcing parts. For 1996, 5.0 liter, they are more than likely GM 305 engines, not ford 302's.

[mhinz000]

thank you for the replies, late getting back on here, havent been able to get out to check the fuel filters yet, they are clearly ford 5.0's. marked as such just as they were if they were in a mustang or f150. its eeic ecm's i have a code reader for it but of course there are no codes thrown during the issues.

[bud37]

Welcome to the forum.......change the filters as has been suggested......maybe run the engines from a remote tank and see what happens with clean fresh fuel. Have you tested the injectors ?

What is an eeic ecm, not sure I have heard of that before . Do you have the rinda scan tool.

Try to replace electric parts with marine parts if you can.