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Hard starting (sorta) 2GM20F . . .

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Jun 30, 2004
Hunter 280 Lake Guntersville, AL
Engine hadn't been used for a few weeks and last weekend the Admiral and I finally made some time for a weekend sail. Temps were mild (maybe 65 degrees) and it took several tries to get her going. When it finally caught, it sounded like it started on one cylinder then the other caught within a couple of seconds. Later in the day it started promptly. It has behaved this way occasionally in the past - worse the cooler it gets but alawys fires quickly when used later in the day. Engine has pretty low hours (I'd guess ~200 hr) and fresh fuel filters and doesn't burn oil enough to notice between changes - once a year.

Edit: Forgot to add that the lift pump and all associated washers were replaced along with both fuel filters very recently. That stopped the fuel weeping issue I had (love the dry catch pan!)

Ideas as to why she won't crank after say 3-5 seconds? Two things I've read in here are air leakage and low compression. I guess either one could be the culprit but I doubt there is air getting in the system; it seems to be problematic only when it is ~60 or cooler. Any other ideas?
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Nov 4, 2010
Beneteau 331 Deale, MD
I don't think this is unusual behavior for the 2GM20F--or at least mine does pretty much the same when it has been chilly. I think the manual says to set the throttle to full when the engine is cold, and then immediately throttle back after it starts. This works for me. Also, you can warm up your cylinders a bit with a couple or few seconds of cranking with the fuel shutoff pulled.
Nov 6, 2006
Hunter 34 Mandeville Louisiana
A tiny air leak in a fuel line can do that. check tighten all the banjo fittings, being careful to not strip them .. Good Luck
Apr 29, 2010
MacGregor m25 Erieau, Ontario, Canada
There's another thread on the board about the same sort of thing. The main advice was to make sure the batteries are good or they won't spin a cold engine fast enough to fire for the first bit.

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Jun 6, 2006
currently boatless wishing Harrington Harbor North, MD
You are fine engine wise

this is VERY typical. Diesels are bad for cold starting. Having a glow plug is helpful but if the engine does not have one the you are stuck making sure that you get as fast a starter rotation as possible.
Since 99.44% of all electrical problems on boats is corroded connections make sure that all the battery terminals are clean and bright. Also know where your compression release is and how to use it to get the engine spinning fast.
Dec 2, 1999
Hunter Vision-36 Rio Vista, CA.

"Assuming" that all of these things check out OKAY, I would suggest that you put a 50w-60w light in the engine compartment and see if the warmth from the light makes any difference in the ability to start.

My old 2GM would be difficult to start if it sat for 4-6 weeks in the cold weather, but would usually fire after the second try regardless of the temps.
Jun 7, 2007
Hunter 320 Williamsburg

I use a hairdryer with a PVC curve to warm up the engine through the air horn. Run ten minutes and she cranks right up in chilly weather.


Nov 1, 2009
Beneteau 36cc port arthur, tx
Do what the manual says. Full throttle then pull back to idle immediately after starting. (no Glow plugs to warm it). I've had two 3gm's - same thing. When the water temp falls to about 70 - 75 f, it struggles. Nothing is wrong, just cold.


Jun 30, 2004
Hunter 280 Lake Guntersville, AL
Thanks for the feedback guys. I have used a dryer and lightbulb before and they worked quite well even at lower temps.

Re: banjo fittings; of the ones I replaced, I am afraid to torque them even more . . . or the others ones for that matter. Shouldn't there be a torque spec for those things? The manual gives ratings (that I've found) based on bolt size and they sound like more than the Al can handle.

Checking electrical connections sounds good. I haven't noticed any slow cranking in particular but every little bit will help.
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