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How to Trouble-Shoot Ignition?

nole76

New member
Hi there, just found this forum! Trying to assist my son with his boat, (97 Luhrs, Marine Power 350 inboards). The starboard engine lost the raw water impeller and overheated. Now that the impeller is fixed, the engine will only fire if you give it a squirt of ether (then it quits immediately). Checking the ignition I noticed that the spark appears yellow and weak. I am really not familiar with these engines, although I know my way around my outboards. Any ideas out there?
 
Sounds like a lack of fuel if it runs on starter fluid and you have spark. A spark is a spark as long as it jumps a spark plug gap. Color shouldn't matter, but then again I'm colorblind. How bad of an overheat was it? If it was prolonged and high heat etc. was a compression check done to assure the is no other mechanical / compression damage? For ignition troubleshooting I use a removed spark plug and connect the outer ground (threads or electrode) to negative ground on the engine. Crank it and watch for a repeating spark. I also have a spark tester that has an adjustable gap and is easier to use. Also visually inspect the plugs, wires, cap and rotor. Most ignition issues with the GM HEI will be either be from fouled old plugs, worn cap and rotor or plug wire routing error. The control modules in the distributors can go bad but tend to be intermittent and gradually get worse. I suspect something wasn't put back correctly during the repair...too much of a coincidence. I bet it is simple like the kill switch or oil sensor sender unit isn't hooked up causing the fuel pump to not run. Is the carb getting gas? You should be seeing the accelerator pump(s) squirting fuel when winging the throttle.
 
the engine will only fire if you give it a squirt of ether (then it quits immediately).

Ayuh,.... Ya obviously have a Fuel Delivery issue, not an ignition issue,.....
 
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