new guy on behalf of a mate (1 Viewer)

[nix76]

Mate of mine that doesn't do Internet has an issue with his fj62. Its a dual fuel which has has been running sweet on both. Weve recently done some work to her, guard swaps speedo cable change few other bits and pieces. Now when its on gas runs sweet as usual but petrol has gone queer. At 2000 rpm it kinda surges, drops revs down to 1400 ish then back up, over 2k its fine, under its fine. Just wondering what we mightve done or any tips ideas.
Thanks in advance

 

[ozwallaby]

Check the fuel cap is venting... try running without it for a test...make sure the tank is not brim full.... if no improvement get 3/4 of a tank... there may be some sediment in the tank that is blocking the fuel pickup..... next is fuel filters and fuel pump... easy stuff first... I know this doesn't fit your symptoms perfectly.... your trouble should get worse as rpms climb with fuel starvation but this is where I'd start...

 

[nix76]

Check the fuel cap is venting... try running without it for a test...make sure the tank is not brim full.... if no improvement get 3/4 of a tank... there may be some sediment in the tank that is blocking the fuel pickup..... next is fuel filters and fuel pump... easy stuff first... I know this doesn't fit your symptoms perfectly.... your trouble should get worse as rpms climb with fuel starvation but this is where I'd start...

Thanks, but it only happens at 2k rpm, at 2.5k 3k or above it runs fine. Was thinking maybe a timing thing, can get an electronic dizzy for around 120 and replace the points one, hoping that might help