Engine Hesitation (missing)

[kev706]

Hi. I have a 1984 DG petrol engine with an anoying fault. Engine starts and ticks over fine but seems to have a slight hesitation when i accelerate,its like its holding back and then picks up.Ive changed the plugs,leads and fuel filter. The timming and CO are ok,the distributor cap and arm seem ok. So any suggestions as to where to check next would be great. Thanks Kev.

[kevtherev]

There's a little pump in your carb
it squirts a little fuel into the throat.

as you depress the accelerator on the opposite side to the cable and throttle assembly there is a little chamber with a diaphragm in it. it should push the diaphragm in.
if it is then two things could be wrong
1. the diaphragm is split
2. the tube to the jet is blocked.

does it hesitate when accelerating gently?

[kev706]

Thanks for swift reply. Yes it is more noticable under hard acceleration (well hard for a t25).

[kevtherev]

quick check
take off the pancake and peer into the carb venturi either get some one to press the acc pedal or twit the throttle yerself.
you should see a jet of fuel squirting down the hole.. not a dribble or a thin pffft but a good hearty pi$$

[kev706]

Just checked by looking in the carb and the jet of fuel seemed ok. So having a spare carb i swapped the diaphragms round to make sure,the one i removed had the number 95 on the brass part of the diaphragm and the other had 85 on. Are they the same? Anyway took the van for a spin and it seems to have cured the problem. Thank you very much for the advice.Kev

[sezicoolcat]

Blimming heck - that was a result! Wish my fixes were always that good

[Red Westie]

Strangely enough called an accellerator pump....lol
Worth checking the distributor vacuum advance unit as well (suck baby suck)

Martin