Advice needed 57 Mercruiser

Can anyone help? Recently boug

Can anyone help? Recently bought Regal Ambassador 255XL built 1990 with 5.7 V8 Mercruiser Thunderbolt ignition. Starts hot or cold most of the time but sometimes will crank all day without starting oddly after adding fuel to tank most commonly. Would very much appreciate any help.

Does it have a distributor wit

Does it have a distributor with an ignition module in the distributor?

Not sure not familiar with the

Not sure not familiar with the engine yet will look next time I can get to her. Thanks for responding.

"steve, when you remove the ca

"steve, when you remove the cap on that distributer, does it have a "white paste" or a "white powder coating" on the pickup coil, shaft, speclking the inside of the cap. the distributers had a problem of oil intruision in the early 90's and the oil would soak the pickup wires causing intermitent opens and no starts. just an idea."

1) Confirm you have non-in

1) Confirm you have non-intermintent 12 Volts DC to/from the ignition switch. Should see 12 vdc on/off on the output side as you on/off the ignition switch. Remove the 12vdc lead from the coil and read the voltage through a voltmeter to ground- voltage should follow the ignition switching too.
2) Confirm fuel flowing to carb or ingection: Remove fuel line just before where the line goes into the Carb. etc. Put fuel line into a clear bottle with a narrow neck so it does'nt pop out...careful! Crank engine and look for fuel flow.

3) check anti siphon valve at fuel tank.