Intermittent starting problems with universal

[aeronca]

Have a Universal m3-20 18hp installed in our Newport 28. First boat for us and first exposure to a diesel engine. Been having intermittent starting problems.
About half the time the time the engine starts right up after holding glow plugs for around 45 secs- 1 min and cracking the cracking the throttle open about 1/3 open.

Other times, using same procedure the engine cranks and cranks and nothing. We ususally wait with the glow plugs on a bit longer and t hen try again. nothing. We repeat this process several times over next 5 mins or so without any luck.

We usually give up and let it set for a while (5-10- minutes and t hen start over with same procedure and t hen it usually starts fine.

Seems odd. Air tempture seems to be same as does everythging else but sometimes it starts right up and sometimes it just doesn't even act like its every going to start.

Engine has low hours (under 300) and battery seems strong, seems to crank strongly and fast. We are new to diesels so we are wondering if it is somethng we are doing wrong.. It also runs and idles fine after started.
Thanks
Allan

[Faster]

Holding glow plugs on longer than a slow 10 count is a bit unusual... it shouldn't take nearly a minute to get things warmed enough to start.

Beyond that it's difficult to speculate - first thought is that your glow plug switch itself may be intermittent.. try to check if you're truly drawing current with the glow plugs switched on (often you'll hear a change in tone of the buzzer as the plugs load down your DC system...)

One other comment - if this is a regular occurrence I'd get into the habit of keeping your raw water through hull closed until the engine actually catches, otherwise you run the risk of back flooding the engine through the exhaust after repeated unsuccessful attempts to start.

[aeronca]

Funny you mention the tone as sometimes it is intermittent, doesn't stay on whole time. However manual does specifify to hold plugs 30-60 secs.

[DRFerron]

Originally Posted by aeronca

Funny you mention the tone as sometimes it is intermittent, doesn't stay on whole time. However manual does specifify to hold plugs 30-60 secs.

Our manual says the same. We can't start the engine with less than 30 seconds on the glow plug.

Our U 5411 had the same problem. For us it was the starter, which ended up being replaced.

[dabnis]

Suggest you take a resistants reading on each plug to ground. Not sure what the reading should be but they should all be about the same, maybe the manual will specify the reading. Then measure the voltage at each plug with the switch on, should be steady.
Check all electrical connections, plugs draw a lot of current. If fed through a solonoid consider replacing that if nothing else is found. Fuel maybe? if you can see the filter(s) bowl it should be full, no air in it. Check allconnections, air leaks are hard to find. Let us know what youi find.

Dabnis

[wescarroll]

It is a fuel problem. If a diesel cranks and gets fuel in correct timing it will run given no other mechanical problems. There is no spark, and the glow plugs make starting easier, but shouldn't be necessary on a hot summer day. I think 1\3 throttle is a bit much for starting, but that may just be your engine. Look at your lift pump and make sure it is delivering fuel correctly, check the fuel filters and bleed the system according to manufacturers instructions. After this point you need a diesel mechanic to look at the fuel timing and injectors, but if you are getting any good run time I doubt it is injectors or timing. That tells me that they are working at least close to proper.

[aeronca]

Sorry for not responding back in the last few days but have pinched a nerve in my neck and have been at home flat on my back for a week now. My boat partner has been out in it a few times the last several days though and has reported no problems starting it. Like I said it could just be us not in tune with this particular engine and its quirks. Hopefully I will get down to the boat this week and try a few of the recommendations. Thanks for all the suggestions I'm sure we figure it out.