[Brooksy]

Hey everyone, I've been driving my sierra for a couple weeks now and sometimes when I put my foot down after slowing down for a corner or taking off it doesn't go straight away? Engine and Carby have been fully rebuilt, only done 1300km so far and is due for an oil change, any help would be greatly appreciated!

[droverdave]

not much information to go on there, can you explain it better? are you talking about a hesitation? how much throttle do you use when it hesitates? if you use more does it take go better?

Did it do this before the carby rebuild?

[Brooksy]

Yeah, it doesn't go, just feels like it's gonna stall sorta thing, more throttle doesn't help the situation either and I never drove it before the rebuild, I bought it with a stuffed engine

[alien]

primary jet too big and its flooding or something?

[droverdave]

Who did the rebuild on the carby?

I suggest you clean the carby out and blow out all the jets.

[Brooksy]

A Carby mob in Adelaide, the guy's done carbies his whole life so I doubt he fucked up, but everyone makes mistakes, could it maybe be my ignition or something? My mate was telling me how much better his GQ went when he changed it over to electronic ignition, could this be worth looking into?

[JrZook]

You already have electronic ignition and they are quite robust. Sounds like its an issue with the accelerator pump on the carb. I'd take it back to your carb guy and see what he reckons.

[SuziBlu]

Jr, if it was the accelerator pump, wouldn't it stumble when trying to take off, a lean off ?

[Brooksy]

Yes! That was what I was trying to explain Suziblu! Hahah sorry I didn't know how to explain it, but that's pretty much it feels kind of like it's going to stall, so my instant reaction is to give it more revs and ride the clutch and have everyone around me stare as if I don't know how to drive a manual! Hahah and awesome, one less thing to change jrzook

[Brooksy]

Checked my ignition today and it's still got points? Doesn't electronic ignition remove the need for points?

[johnmath]

Brooksy wrote:

Checked my ignition today and it's still got points? Doesn't electronic ignition remove the need for points?

Only if your ignition system has been replaced with a non-standard one...

Ignition problems can cause hesitation on acceleration, but will usually show up a lot of other engine issues as well, like rough running. The common reason for stalling or hesitation on acceleration is a faulty accelerator pump in the carburettor, which can be as simple as the linkage for the pump falling off because a retaining clip wasn't clipped on correctly. The first thing you should do is get the guy who did the carburettor to look at it. He will know what's wrong in a few seconds flat.

[Brooksy]

Must have been changed then, why would someone change it back to points though haha and yeah it's just hard as I can't get down there during business hours unless I take time off work, so I'm trying to sort it out by myself first, I'll try have a look for a broken linkage or something, bought some Carby cleaner today too just incase

[droverdave]

Points will still run fine if adjusted correctly.

[Brooksy]

Changed my oil and fuel filters today for the 1000km run in, didn't find any broken linkages on the carby, sprayed some Carby cleaner in the Carby and that didn't do much, opened her up to 5k rpm on the way home to blow the cobwebs out, I'll see how it runs tomorrow morning

[johnmath]

You can test the accelerator pump yourself. Take the cover off the carburettor so you can see down the throat. The accelerator pump jet discharges into the primary barrel, which is the one with the choke butterfly. You might need to hold open the choke butterfly open so you can see into it.

When you open the throttle, you should see a strong stream of fuel squirting into the primary barrel from the instant the you start moving the throttle. Any breaks in the stream or dribbles means that something is not right with the accelerator pump.

This video shows a similar Aisan carburettor and about four minutes in shows the accelerator pump linkage operating. Disregard references to the auxiliary electric accelerator pump, because Aisan carburettors on Sierras don't have them. https://www.youtube.com/watch?v=81RfJnO5C40

[tomtheshooter]

My Zook looses power for a second after any tight left corner. Im told by my mechanic its a Sierra thing, something to do with the fuel in the carby all going to one side and nothing to worry about.

[droverdave]

Or the float is out of adjustment.

[JrZook]

Brooksy wrote:

Checked my ignition today and it's still got points? Doesn't electronic ignition remove the need for points?

That is very bizzare. Got a pic? Must the ultimate el-cheapo/dodgy fix ever!

[Brooksy]

Thanks everyone! I'm hoping to switch to a gsxr 600/750 setup eventually, so I won't need to worry about that tom, although that seems a bit bullshit to me, surely they wouldn't realease a car with an issue like that! I'm not even cornering that hard anyway and I'll see what I can do Jr, I'm on my phone and I've been flat out with work, but I'll hopefully get time tomorrow after work to sign up for a photo account thing