1.9 DG Wont idle

[Brian1]

Hi my 1990 T25 1.9 DG broke down on the M25 in heavy traffic. We had been crawling along for about an hour when suddenly the engine wouldn't idle. It restarted easily but wouldn't idle it just stalled. The AA came and he got us going - I think he opened the idle screw on the carb by a massive amount and the idle speed was fine although running rather lumpy. However by the time we got to our destination about 5 miles away the engine was revving a lot when it should have been idling. We adjusted the idle screw to slow it down and it was still running rather lumpy. On the journey home it again started revving again and the screw needed adjusting again to slow it down. Now all seems to be fine again and the lumpiness has gone.

I would like this not to happen again as breaking down on the M25 in the rain on a Friday rush hour was not a pleasant experience!

Could it be dirt in the Carb?

Something wrong with the idle cut off valve?

Something wrong with the power connection to the idle cut of valve?

Something else?

Any help would be much appreciated.

Thanks

[kevtherev]

Hi my 1990 T25 1.9 DG broke down on the M25 in heavy traffic. We had been crawling along for about an hour when suddenly the engine wouldn't idle. It restarted easily but wouldn't idle it just stalled.

Something wrong with the idle cut off valve?

Something wrong with the power connection to the idle cut of valve?

bingo... you got it
And yes it could be a blocked jet but check the easy one first


Now the AA man has messed with your idle speed screw, he's wound it right in as a temporary measure

I assume you've searched this forum (mechanical) and found the simple test for the valve?

[Brian1]

Thanks Kev

Will what the AA did have messed things up? I assumed that if I just adjust the idle screw (the one inside the long pipe thing )to a position where the idle speed is about right then all would be well. Am I being too simplistic ? !

Brian

[kevtherev]

No your not

once the problem has been found and rectified the rpm will shoot up' use this screw to turn it down.

All he's done is bypass the air bleed jet by opening the butterfly further.

this jet may be blocked see

[kevtherev]

easy check for the cut off valve.
Ignition on
pull apart the connector
re connect and you should hear an audible "click"

no click means it has failed

[kevtherev]

it's on the carb and has a black wire going to it..
OK here it is laid out
you have..

a manifold heater .........Thicker pink wire that disappears under the manifold
a fuel cut off solenoid
and a choke heater

the manifold heater will be the larger red/pink wire, with a white connector and needs to be through the sender switch( from thermostat housing on late cooling system) and relay No1..

the fuel cut ouff solenoid, the choke heater and the other black wire all loop into the same ignition live (black) wire on spade connectors. two female and a male

NOTE these pictures are from an earlier cooling system, so the coolant pipes will be confusing to you.
ALL you are interested in are the wires



here is the thicker wire with the white connector, then the black wire runs off too..



.... here connected to the cut off solenoid (white connector) and choke heater (yellow connector)

[Brian1]

Thanks for all this Kev. I will have a good look around tomorrow.
Great to see the pics too.
Thanks

[scottbott]

mine gave a similar problem,checked out the cone shaped filter on the carb inlet and took the top off the carb and removed the jets blew out with a compressor refitted and been sweet as a nut since

[kevtherev]

Yes a blockage of any sort will cause this. I hope he cleans the jets filter first