Hard to start 454xli

My 1996 carver has twin crusad

My 1996 carver has twin crusader 454. Since replacing the fuel filters (racor #110) one engine requires 2-3 minutes of cranking before starting. We pause every 15 seconds. After warm up it runs perfect. And will restart. The other engine will start up right away also had filter changed as well. It sounds basic but is it losing it's prime? Recently when trying to start the engine I had my wife crank the engine over and I pressed what looks like a valve stem )loacted between the Racor filter and an inline filter)and it started right up. Is there something my mechanic could have forgotten when he replaced the filters.

"I'm thinking more likely

"I'm thinking more likely an air leak.

What is the fuel delivery scheme; electric or mechanical? are filters before/after the pump.

The only 'valve stem' looking item I can think of is a schrader valve - those are typically on the pressure side of injected systems (valve stem with the cap removed).

When "I pressed what looks like a valve stem " are you describing depressing the little rod in the center or just covering up the "open end"? Any noise, liquid, etc?"

"I was depressing the little r

"I was depressing the little rod in the center.
I think a little gas came out. I didn't hear anything because the engine started up. I think I have electric fuel pumps. If I had an air leak wouldn't I have some gas fumes also?
There is nothing present.
One more thing, right after it starts if I try to increase the throttle too fast it will die and be hard to start again. After a 5 minute warm up it runs perfect though I ran at least 30 minutes at a 3200 cruise no problem. I even ran it up to 4000 for about 20 seconds and it performed normally. There are 710 hours on the engine with original wires and plugs. I have only changed the oil on the engine every 50 hours. or yearly. Before they changed the fuel filters this engine would die out but start up right away. It no longer dies out."

"My thought was air leak on th

"My thought was air leak on the suction side. I'd guess it isn't huge but is enough to cause problems after the boat has sat a while (& the fuel has run back down the line, into the tank. If the leak is as suspected, you wouldn't necessarily have a drip or fumes present.

Is this injected or carb'ed?

Can you verify electric pumps? Do you hear it run when the key is turned to ON?

Had you made sure the filter cartridges are on tight?"