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Old 08-04-2010, 03:31 PM   #1
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Lehman Starting Issues

For all those Lehman 120 owners out there how well does your enging start??

With mine it starts rough so you have to give it a bit of throttle to start which is not right.

It sounds to me as though there is a fuel problem either starving or air.

I have found neither ATM

Does the Minimac fuel pump have a filter in the pump somewhere??

I saw another post on a forum somewhere with the same problem however they never gave the solution.

The engine runs fine once it has run for a couple of minutes and restarts ok.

Allan

-- Edited by AllanY on Wednesday 4th of August 2010 03:36:32 PM
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Old 08-04-2010, 04:42 PM   #2
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RE: Lehman Starting Issues

Quote:
AllanY wrote:

The engine runs fine once it has run for a couple of minutes and restarts ok.

Allan

-- Edited by AllanY on Wednesday 4th of August 2010 03:36:32 PM
Allan,

Is there a valve that is letting the residual pressure in the fuel line to the injection pump*bleed off after it sets for a while?** The pressure may be fine for several hours after the original start but falls off enough after it sits for a while*that it takes some spinning up to get the fuel back into the pump.

Just a guess.*

*
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Old 08-04-2010, 05:08 PM   #3
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RE: Lehman Starting Issues

JD

That was one of the thoughts I had however I have no info on the minimac fuel pump so I had hoped there was someone out there who knew as I am in OZ I don't have access to some of the info in the US

Allan
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Old 08-04-2010, 06:37 PM   #4
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RE: Lehman Starting Issues

What do you mean by "starts rough"?

Does it shake and rattle on the mounts? Does it smoke white? Does it seem like it's only firing on a couple of cylinders? Does it start instantly but idles rough? Does it crank for an unusually long time before starting?

What does "rough" mean? Does it start smoothly if you advance the speed lever?

You do know of course that all that "throttle" thing does is set a speed point on the governor and unlike a gas engine it does not directly control the amount of fuel going to the cylinders? You could set it any place you want and the engine will still start with the same amount of fuel.

You might have a case where the idle speed stop has backed off so that the idle is too low, does the speed increase once it gets over being "rough"? Is it "hunting" rather than misfiring, does the speed seem to go from very slow, almost stopping to up a number of revs then back down again in a cycle until the engine warms up?
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Old 08-04-2010, 07:32 PM   #5
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RE: Lehman Starting Issues

Hiya,
** A former Lehman I owned used to start up right away.* No throttle fiddling as such.* Current Lehmans need a bit of throttle wiggling but DO start without fail within 3-4 seconds.* Maybe I should be concerned, but I'm not at all.* They run reliably, evenly *and strong.**
** As far as I know, there's no filter in the pump.
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Old 08-04-2010, 07:42 PM   #6
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Lehman Starting Issues

Rick

You have to wind it over and it runs like only firing on half the cylinders
No it does not blow white smoke
If you advance the throttle it starts fine but at higher revs
It idles fine once it has run for 1 minute but now that you mention it at only about 500rpm i think
It will start after that with no problem once it is warm no hunting or miss firing
You could have hit the nail on the head with the slow idle
What are these supposed to idle at?? 650 700??

Dose anyone have any info on adjusting the idle onthe minimec pump??

Allan

-- Edited by AllanY on Wednesday 4th of August 2010 07:43:07 PM

-- Edited by AllanY on Wednesday 4th of August 2010 07:51:43 PM
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Old 08-04-2010, 09:30 PM   #7
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RE: Lehman Starting Issues

Set the idle around 6oo rpm plus or minus, whatever feels good and works best. Look for an adjustment screw that sets the speed lever slow speed position. Have someone move the throttle from idle to full speed while you watch what moves on the governor. When the lever is at idle, note the screw that prevents it from moving further. Unlock that screw and "tighten" it to move the lever very slightly toward the high speed position. Lock the screw and start the engine to see how it starts and idles. You can adjust this while it is running if it doesn't bother you to work on a running engine. Some people don't like to do that.
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Old 08-05-2010, 07:40 AM   #8
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RE: Lehman Starting Issues

Allan, my Lehman is quite bit older than yours, yet always starts first pop and purrs like a kitten, but the idle speed is about 650, as Rick suggested, so it's probably something simple like that if it runs smooth when hot.
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Old 08-05-2010, 03:17 PM   #9
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Lehman Starting Issues

Hi Peter
Yep I am inclined to agree

I just need the adjustments for the Minimec CAV pump now.

Which is the idle adjustment screw

On the top or at the aft end

I have had nothing to do with these pumps before so I don't want to adjust the wrong thing.

I am going down to the boat today so i'll see what I can work out.

Maybe someone can throw some light on this photo I found on a forum somewhere but can't remember where.

Rick

Can you throw some light on this??

Allan

-- Edited by AllanY on Thursday 5th of August 2010 03:23:52 PM
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Old 08-05-2010, 03:41 PM   #10
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Lehman Starting Issues

Would love to help you but there are so many variations of injection pumps and linkages on Lehman engines I would not even risk trying to provide specific details without a photo of your installation.

If you follow the generic instructions I posted you will find the right screw or adjustment point, absolutely guaranty it*

I'm not going to promise that doing what I suggested will cure the problem but I am fairly confident it will. If it were my own engine, that is the action I would take first. You cannot harm it by adjusting the idle stop so there is no risk involved.

Good luck and enjoy the troubleshooting experience, it will be a confidence builder no matter what.


-- Edited by RickB on Thursday 5th of August 2010 03:43:58 PM
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Old 08-05-2010, 05:50 PM   #11
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RE: Lehman Starting Issues

Normally the adjustment screw is round the back of the pump in between the engine block and the pump. If I remember right you need quite a long screw driver to do it. You cannot see it in the picture posted. Have a look and see with a torch.
Cheers, Leon.
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Old 08-05-2010, 06:42 PM   #12
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RE: Lehman Starting Issues

Where you been Leon? How about some boat pictures, assuming you have finished.
Mike
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Old 08-05-2010, 10:31 PM   #13
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RE: Lehman Starting Issues

Hi Leon

Spot on the money
I just need to work out how I am going to get at it but where there is a will there is a way
Thanks for your help

Allan
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Old 08-06-2010, 09:09 AM   #14
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RE: Lehman Starting Issues

Hi I'm still here. *Actually the boat is not finished, apart from using it as a tow boat a couple of months ago it has sat on it's mooring for the last ten months. *My mother had a stroke late last year and the boat took a back seat for a while as I was too busy between work, kids and trips back and forth to Australia. *I am thinking about hauling this month for antifoul and then plan the interior. *Don't worry, there will be some pictures when it gets happening again.
Cheers, Leon.
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Old 08-09-2010, 03:23 AM   #15
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RE: Lehman Starting Issues

Well I tried the starting at the weekend and just advanced the throttle and started no worries.
I didn't have the tools with me to make the adjustment on the pump but tha't all it is.
thanks Leon

Allan
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Old 08-11-2010, 06:33 PM   #16
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Lehman Starting Issues

The operators, parts, and service manuals for the FL120 are on the Grand Banks owners site. Accdording to our own FL120 operators manual, the starting procedure for the FL120 under "normal" ambient temperature conditions is to advance the throttle one quarter of the arc of travel and push the start button.

When the engine fires we reduce the power setting to a fast idle of 1,000 rpm or so although that's about where it ends up anyway with a quarter throttle. Once the engine has been running like this for a few minutes we reduce the idle to about 700 rpm. *All the way back with a warmed-up engine should produce an idle speed of about 600-650 rpm.

We've had the boat for twelve years and use it year round and while the engines could explode tomorrow they so far have started almost as soon as the starter begins to turn them. I initially used less than a quarter throttle when starting and they did not fire up as rapidly and positively as they did when I started using the recommended*quarter throttle setting.


-- Edited by Marin on Wednesday 11th of August 2010 06:37:07 PM
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Old 08-12-2010, 03:05 AM   #17
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RE: Lehman Starting Issues

Thanks Marian

Just not used to starting a marine diesel by advancing the throttle but if that is how it is done than that's how i'll have to do it
Thanks

Allan
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Old 08-12-2010, 03:58 AM   #18
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RE: Lehman Starting Issues

"Just not used to starting a marine diesel by advancing the throttle but if that is how it is done than that's how i'll have to do it."

Some govs go to full fuel while cranking , others just to where the throttle is set.

Fairly common to need full throttle while cranking , with a pullback as she lights off.

Mostly weather the Gov thinks truck or boat .
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Old 08-12-2010, 05:52 PM   #19
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RE: Lehman Starting Issues

Quote:
AllanY wrote:
Just not used to starting a marine diesel by advancing the throttle but if that is how it is done than that's how i'll have to do it
That's what the FL120 manual says to do.* But it may not be the correct procedure for other makes and models of diesel.**So don't regard it as a universal procedure for everything.
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Old 08-12-2010, 06:21 PM   #20
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RE: Lehman Starting Issues

Marian

Point taked however I had another boat with a 80hp Lehman and didn't have to advance the throttle but it was only the 4 cylinder one.

I have started hundreds of marine diesels over the years in my job and have never had to advance the throttle before hence my original question.

In saying that I could probably up the idle speed to 650rpm and I think that might solve the problem as we don't get the extremely cold weather here.

Allan
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