Hard Restart - Maxum Boat Owners Club

speedysprocket · 08-14-2016, 02:53 PM

One of my 7.4Ls is being very stubborn with restarting when warm. Like if we anchor somewhere to fish or swim, when I go to start again, it takes a lot of cranking. I've tried just cracking the throttle and various amount of pumping with open throttle and still ends up in cranking a while at WOT before she fires.
It's a 94 Gen V with Thunderbolt IV ignition. Cap, rotor, and wires are all old so I should replace them, but wondering if there are any other ideas. I'm going to pull the top off the carb and see if it's all dirty again, but I've been running it weekly with fresh gas and filter, so that shouldn't be an issue...

mmwjr · 08-14-2016, 05:14 PM

Does it have a carb? Common issue with carbs that need to be freshened up as they tend to dump gas when shut off.

speedysprocket · 08-14-2016, 05:15 PM

Yes they're carb engines. New rebuild kits over the winter and when I put the boat in, they were full of sediment and gunk already, so I cleaned them again and put new filters on.
Cold starts are fine and once I get it running, it's good too. Just got restarts are tough.

mmwjr · 08-14-2016, 05:19 PM

Look to see if it drips gas down the throat when you shut it off.

speedysprocket · 08-14-2016, 07:45 PM

I'll check. Thanks

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Baby Blue · 08-15-2016, 08:11 PM

Your choke may needs adjusted. I had same problem with similar engine and carb '98 7.4 with weber carb. next time it's hard to start remove flame arrestor and see position of choke, sounds like too much choke when engine is warm and flooding engine.
How to start carbed flooded engine? full throttle and crank for longer periods of time.
BB

speedysprocket · 08-16-2016, 01:51 AM

Quote:

Originally Posted by Baby Blue

Your choke may needs adjusted. I had same problem with similar engine and carb '98 7.4 with weber carb. next time it's hard to start remove flame arrestor and see position of choke, sounds like too much choke when engine is warm and flooding engine.
How to start carbed flooded engine? full throttle and crank for longer periods of time.
BB

The choke on that engine actually doesn't close all the way. I think it needs a new spring. But it's wide open when the engine is warm. I have checked that.

cdhunter · 08-16-2016, 09:20 PM

I had a 97 2700SCR with a 7.4L/carb and it had a similar issue. I also noticed that if I let the boat sit for a week, it would take longer to start, since the float bowls were dry. If the engine was warmed up and I shut it down and then immediately restarted it it would fire up instantly. I discovered that the well plugs in the bottom of the float bowls were leaking after shutdown and flooding the engine. I finally ended up replacing the Mercrusier carb(Weber?) with an Edelbrock marine series carb.

speedysprocket · 08-16-2016, 09:32 PM

I opened the carb today and found minimal sediment. The bowls were also still about half full. I didn't see any dripping after shutting the engine off. I think I did notice I had the accelerator pump pushrod in the middle hole instead of the inside hole, so it was pumping a little extra fuel. Maybe that was enough to flood it?
She starts up easy when cold and sitting for a while though...

cdhunter · 08-16-2016, 09:49 PM

Well if she starts up after sitting a week without having to turn over the engine for 15 - 20 seconds before she fires, then it is probably not the carb bowls draining into the engine. When the engine is difficult to warm start have you checked to see if it is flooded? How long has it been since the last tuned-up?

speedysprocket · 08-16-2016, 09:51 PM

I does act flooded.
Got new plugs and carb kit over the winter. About to get new cap, rotor, and wires too.

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cdhunter · 08-16-2016, 09:59 PM

When you are warm starting your engines, do you pump the throttles?

speedysprocket · 08-16-2016, 10:01 PM

I start off trying without, then cracking, then WOT

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cdhunter · 08-16-2016, 10:07 PM

In my experience, you normally should not have to pump them after the engine is warmed up. Next time before you warm start, you may want to pull the flame arrestor, with the blower running, and check the carb to see if it smells flooded. If it does not smell flooded, have someone pump the throttle to see it the jets are squirting gas. Hopefully you will be able to zero in on the cause.