slight hesitation when accelerating

[markey b]

bit of a silly one, there is a slight hesitation when accelerating on my raider, press the throttle and it pauses before it goes, only started to notice it recently when driving it hard and accelerating out of corners.

its a std carb as far as i know, but with the acc pump union bit open to air (doris mod?), and 11psi on a standard t2

i've taken the top off and blown out the brass acc pump jet so thats clear, and i've checked the linkage underneath operates and all seems ok.

i've also noticed that its worse with a dump valve fitted, take it off and its less noticable when it hesitates

i had idle jet issues, poor idling etc, and resolved that with a new o ring, i'm a bit reluctant to remove the idlejet out the side unless its a suspect, as i always have to clean them 20times before it runs ok again :laugh:

also it runs and ticks over beautifully, so i'm not sure if the mixture screw could have anything to do with it?

sorry for such a nooby question!!

[michael tierney]

i,ve had a problem like that for a while now,also when i accellerated hard and then change into neutral it cut out! so i changed the coil and all is well:)(well it was nearly 20 years old):o

[James George]

bit of a silly one, there is a slight hesitation when accelerating on my raider, press the throttle and it pauses before it goes, only started to notice it recently when driving it hard and accelerating out of corners.

its a std carb as far as i know, but with the acc pump union bit open to air (doris mod?), and 11psi on a standard t2

i've taken the top off and blown out the brass acc pump jet so thats clear, and i've checked the linkage underneath operates and all seems ok.

i've also noticed that its worse with a dump valve fitted, take it off and its less noticable when it hesitates

i had idle jet issues, poor idling etc, and resolved that with a new o ring, i'm a bit reluctant to remove the idlejet out the side unless its a suspect, as i always have to clean them 20times before it runs ok again :laugh:

also it runs and ticks over beautifully, so i'm not sure if the mixture screw could have anything to do with it?

sorry for such a nooby question!!

undo the doris mod by taking an air feed from a spare port on carb top if you have one. I run a pipe from far side so the slight leak on the accelerator pump does not affect fuel pressure reg.

I know you've checked but just make sure you have the accelerator pump linkage adjusted correctly.

[James5]

Agree with Mr George, check your accelerator pump linkage has been adjusted to the correct setting.

[markey b]

i'll re-pipe the acc pump tonight, and if that doesn't work i'll whip carb off at weekend and check the rod and gap

silly one, what does doris mod do? :rolleyes:

[dangerous dave]

im in the same boat, while holding rev's in any gear and its jerking and while feeding the throttle its taking a moment to pull through... on boosts fine, idles fine..

got the engine moist the other day and a missfire popped up, i think mine might be down to a dizzy being a bit shafted or maybe a buggered ht lead.. might go run it when its dark and look for arc'in while reving it.. :)

or i'll rebuild the carb and replace the plugs, leads, dizzy etc, cure the fault and never know what/which it was:cartman::p

[Jimmy_GTT]

Have you guys checked the accelerator rod / pump? If it is pumping fuel well?

[jonnyshaw49]

hi ive got exactly same was having idling issues so rebuilt my carb set acc rod with 5mm drill bit. when the car is in neutral idling and you rev it it hesitates before revs rising but i havnt got the juddering i used to have when you let the revs off anymore. would changing the gap with a bigger/smaller drill bit cure the problem?what else could be the problem i have no air leaks checked with carb cleaner around all connections. what coil could it be the on on aei???

[Brigsy]

The acc pump linkage probably wants adjusting. Fitting the ref pipe back on will make no difference. I binned it many miles ago on the van with no probs.

[Shane P]

I had that problem on and off before too. Firm push on the king lead into the top of the cap, a tiny bit of fuel injector cleaner and it hasnt done it since :confused:

[James George]

i'll re-pipe the acc pump tonight, and if that doesn't work i'll whip carb off at weekend and check the rod and gap

silly one, what does doris mod do? :rolleyes:

as the air feed to back of the accelerator pump is on the same line as that to the fuel pressure regulator, doris mod ensures the pressure reg recieves full monty pressure (and provides enough fuel) as the pin on the diaphram of the accelerator pump can leak a little air (some more than others).

[jonnyshaw49]

will opening or closing the gap on the acc pump with a different drill bit make a difference to the hesitation???

[Jimmy_GTT]

will opening or closing the gap on the acc pump with a different drill bit make a difference to the hesitation???

Have you checked that the acc jet spraying well if you push gas?
As I remember you have to shorten the rod.