GT-40 Hard starting issues when warm

[jbach]

Been battling this for a couple of years now. Has been about 3-4 yrs/150 hours years since last full tune-up of plugs, wires cap, rotor, fuel filter, etc. Engine starts 100% perfectly on cold start up.

This issue seems to be getting worse, ie cranking longer before finally catching. Recently it is taking 5-6 or more seconds until finally turning over. I need to add that by advancing the throttle, it seems to start faster. I'm not sure what that means though, being fuel injected.

On a whim, I replaced the TFI with no change. I believe it was last year I replaced the relays, no change. The fuel rail holds 37 lbs for 10 plus minutes when key is in on position. Both the fuel rail and FCC hold 33-34 lb at idle, and 30-31 at 2K rpm. I cannot seem to recreate the problem on the hose out of the water.

Anyone have any ideas? Something seems to be getting heat soaked.

[homer12]

Check all electrical grounds for corrosion. Start by replacing battery cable ends. I thought I had a starter going bad once and this was all it was. Fine cold. Then once warmed up would drag terribly. Couldn't even tell the battery cables were bad until I cut them out and replaced.


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[kmarine]

does it start and die or just hard starting. If you turn off for minute or so does it start backup or is this after a half hour or so sitting anchored. when was your last tune up. Are you aware that the low pressure fuel pumps sometimes struggle on these if hot. The more info we have the easier it is to find the cause of your problem.

[jbach]

does it start and die or just hard starting. If you turn off for minute or so does it start backup or is this after a half hour or so sitting anchored. when was your last tune up. Are you aware that the low pressure fuel pumps sometimes struggle on these if hot. The more info we have the easier it is to find the cause of your problem.

Thanks for the reply. I have experienced no start and die issues. once started and running, it runs great. it seems as though if restarted right away, like right away, it will restart without problem. if sitting for more than a minute or two, like when changing riders, it will crank for longer than it should, maybe 5-8 seconds cranking.

That's kind of why I'm thinking it's a heat soak issue, or vapor lock, but i've read that vapor lock is not likely. Also, I can't seem to recreate the problem in the driveway on the hose. possibly because the hatch or rear seat is out, keeping something cooler.

I'll keep the fuel pressure gauge connected next time we're out riding to make sure i'm getting good pressure out of the fcc when hard starting.

Is 34 lbs at idle adequate? I thought I've seen 39 lbs +- 5 lbs is w/in spec?

[kmarine]

I have had a lot of fuel pump issues with the low pressure pump feeding the fuel cell. when the pump Is cool. the high pressure pump works properly and sends the proper fuel prssure to the injectors. When they begin to fail they usiually do when hot. what would happen on a restart is that the fuel control cell level will drop and starve the high pressure pump intermittently. When the engine is running the high pressure pump is assisting the low pressure pump until you shut off the engine and disrupt the fuel flow. when you go to restart the fuel expands and vaporizes in the fuel cell and starves the high pressure pump. Please note mercruiser and Volvo have similar issues and merc recommends two low pressure pumps on some models Yes, three fuel pumps. in your case you may be able when hard starting to cycle fuel pumps a couple times to reset the low pressure pump to ptime the fcc. If you have not replaced your low pressure fuel pump I would start there. I get only about 5 years out of them.

[jbach]

Thank you. I think I'll give the low pressure pump a go and see what happens. It's original to the boat, 17 years isn't too bad.

[kmarine]

You can order the carter low pressure pump for about $65 from online dealers with a different universal electrical connector. the pcm part is over $200 for the same pump with different part number google carter marine low pressure fuel pump.

[kmarine]

Just had another boat in with similar problem. After replacing the cap and rotor, did you check the timing there is a black clip to remove on top of engine before setting to 10 degrees BTC. If the timing is off you may have starting issues. In this case the engine was too far advanced and difficult to start when hot.

[SilentSeven]

Suggestion from another forum...

http://www.correctcraftfan.com/forum...-start-problem