DB 996 Not revving as high as it should

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User avatar
swarv
Posts: 12
Joined: Tue Jul 09, 2013 10:33 am
Location: Sussex

DB 996 Not revving as high as it should

Post by swarv » Sun Apr 13, 2014 8:26 pm

Hi all,

I have a DB 996 and it only revs to 1600 rpm. It used to rev more.
I was wondering what could I check on this to make it run better?

thanks

Martin
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odin
Posts: 662
Joined: Sun Oct 31, 2010 9:31 pm
Location: Huddersfield, West Yorkshire.

RE: DB 996 Not revving as high as it should

Post by odin » Sun Apr 13, 2014 8:48 pm

When were the fuel filters last changed ? Also what is the bottom of the fuel tank like ?
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swarv
Posts: 12
Joined: Tue Jul 09, 2013 10:33 am
Location: Sussex

RE: DB 996 Not revving as high as it should

Post by swarv » Sun Apr 13, 2014 9:22 pm

Fuel filters last year, probably time to do again.
not sure about the fuel tank, don't know how to check.

thanks
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Guest

RE: DB 996 Not revving as high as it should

Post by Guest » Sun Apr 13, 2014 9:37 pm

Have you ever cleaned the plastic/nylon gauze filter in the injector pump? It's under the larger union fuel pipe from the front fuel filter so perhaps you can check it when changing the filters.

The rate that the fuel comes into the lift pump sediment bowl will give a good indication of any restriction in the fuel tank but I would also be inclined to clean out the lift pump as well, glass bowl, metal gauze, if there is one, and the recesses in the body of the pump, they also fill with sediment.
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db2d
Posts: 2151
Joined: Fri Feb 24, 2012 10:01 pm
Location: Monmouthshire

RE: DB 996 Not revving as high as it should

Post by db2d » Sun Apr 13, 2014 11:39 pm

Check the security of the throttle linkages and connections. Check the movement and security of the throttle lever on the pump
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JamesF
Posts: 1327
Joined: Tue Mar 14, 2006 8:49 pm
Location: South Yorkshire

Post by JamesF » Mon Apr 14, 2014 9:30 am

Disconnect the throttle rod to the injector pump and rev it up directly on the lever on the pump. If it runs at full revs then it's a problem with the throttle linkage. There's various pins and clevises etc that can wear in the linkage causing play resulting in excess travel within the throttle linkage system.
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SteveCollett
Posts: 585
Joined: Wed Sep 24, 2008 8:17 am
Location: Suffolk

Post by SteveCollett » Mon Apr 14, 2014 10:06 am

has it got a foot throttle
mud under this will stop it revving I think
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broadsword
Posts: 1707
Joined: Thu Jun 12, 2008 9:17 pm
Location: Holmfirth, Huddersfield

Post by broadsword » Mon Apr 14, 2014 10:37 pm

Had a similar thing on my 990 - she revved to approx 2050rpm, adjusted the throttle rods and she now revs out at 2200rpm but on full hand throttle she will go to approx 2250rpm - I suppose they just wear/stretch over time???

Cheers

Andy
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bedwards1966
Posts: 885
Joined: Sun Mar 07, 2010 10:36 pm
Location: North Yorkshire

Post by bedwards1966 » Mon Apr 14, 2014 10:41 pm

Check all the filters - sediment bowls, lift pump gauze, injector pump gauze, check the linkage is giving full movement at the pump, then check you have a good flow of fuel from the tank to the lift pump.
If everything seems good then suspect the lift pump, it may not be delivering enough fuel. There is a strong possibility that the plunger which operates it has worn meaning there is nothing wrong with the lift pump but it can't operate fully. You could try with the throttle wide open and pumping it by hand as fast as you can, see if it improves the revs.

Also remove the air filter hose at the manifold to check there isn't a restriction, such as a collapsed hose. You should see loads of black smoke if this is the case, but it pays to check.
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