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1490 air locking

Posted: Sun Jan 05, 2020 11:58 pm
by Wheelie
Hi, have a 1490 that has started to airlock when fisrt started if was lying up for a few days,there is a small diesel leak coming from the excess fuel switch under the injection pump but this leak has been there for at least a few months with no probems, (the injection pump had been reconditioned less than a year ago but this leak has appeared anyway), also some diesel is slightly coming from the heater plug,looks like a very small amount thou, it started no problem this morning and ran for about 20 seconds at least, totally smooth, and then stopped,so had to bleed a lot of air out, when it did start all was fine again, that's the second time in about 2 weeks it did that,just wondering if anyone has some ideas? Thanks

Re: 1490 air locking

Posted: Mon Jan 06, 2020 5:39 am
by ollek
The reason for this is most likely a betwen the lift pump and the fuel tank or a blockage of the suction pipe in the fuel tank. Start by checking if there is dirt in the fuel tanks blocking the suction pipe and check that the glass bowl on the lift pump is sealing correctly against the pump body. .

Re: 1490 air locking

Posted: Mon Jan 06, 2020 1:28 pm
by Wheelie
Well before I started it this morning I bled it and air did come out after a few pumps of the lift pump and took about four or five pumps to clear it, the diesel was flying out no problem from the injection pump, it started and all was fine, I took off the lift pump bowl there was a little dirt on the small filter but nothing too much,was at least six months since that was off, cleaned around seal and all seems good there,bled it and started again and running good, would it be possible that the leak from the excess fuel switch could cause it, but as I said that small leak was in it now for a few months at least and no problems,have a 1390 with a small leak from same place for ages and no problem with it though,thanks

Re: 1490 air locking

Posted: Mon Jan 06, 2020 1:48 pm
by db2d
It could be the fuel is draining back to the tank if one of the valves in the lift pump is leaking.
There is a small seal in the cold start device that can easily be renewed. This seal is only available from davidbrownparts.com unless someone has old stock. It is not included in any other seal kits.

Re: 1490 air locking

Posted: Mon Jan 06, 2020 5:12 pm
by Wheelie
Right thanks for that, just started it this evening and all was fine anyway , strange!