TwoKs

I'm trying to start my engines for the first time and seem to have ign problems. Intermitting spark. I don't know whos module's these are either.they are about 6" or 7" long 3" or 4" wide finned on top and mounted on what looks like factory bracket on back of engines. Any body know if they are merc or accel. I can't find anything in merc manual on them. I replaced the pickups in the distributors. If I take the two wires going to the pickup and start tapping them together I will start getting spark on my spark tester. spark will stay and go away and than start again. One engine started running fine and keeps starting now but other engine still has problem. When it finally starts, it will run great for about a minute than its like some body turned the key off .No spark again untill I take the wires off dist again and start tapping them together again. I also have to crank the hell out of it to start. one minute and again it shuts off. Any body have any idea's Ihave already powered the ign boxes with seperate battery and cranked with another to make sure it's not voltage drop problem. these are carborated 502 engines with machanical fuel pumps 1994's or 5's HELP!!!!!!!

HOTROD2

It sounds like a ground problem. Make sure the distributer is grounded to the engine block as well as the ignition box. Is the ignition box blue ? It might be a Jacobs ignition if it is. If not grounded good the box heats up and shuts down stalling the engine and will be hard to start.

TwoKs

Thanks for input hotrod. Today I cleaned all grounds and tried again. Still same problem, so I removed the box from other engine and switched it to problem side and it runs great, Now I know I have a bad module. So I call mercruiser dealer and he looks up my engine numbers and these modules turn out to be mercruisers high performance modules and coils. the module alone to replace is about 900.00 to 1000.00 I ask what stock module for this engine will fit and he said they don't make that module any more.He called up mercruiser to see what stock setup I can use and we are waiting for reply.Does any body have any idea what module would work well on these engines They are 1994-5 502 465hp. The previous owner had the engines redone with some cams put in. I don't know what cams but they are hyd. not solid. They do have a loppy idle, but not real rough. he said he ran about 6000 rpm. The module wires to the distributor are held on with nuts not plug in any info would help