Car mechanics on the shore for a cash job?

[biketimus_prime]

Hey chaps, I know it's not bike related but I figure it's a good place to ask anyway.

Anyone here good with old carburetted engines? My 1995 nissan datsun ute is playing up. NA16 engine. It's not that great on gas and when I start it, it idles really high at first and even after a bit of driving. Then after it warms up a bit, the revs drop right down and it struggles to idle and almost dies. I need to keep my foot on the gas to prevent it. I sorted all the vacuum hoses as there were split ones but I'm not too keen on attacking the carby myself as I don't have enough time and I don't want to rush it. I also don't want to mess up things and then end up taking it to a mechanic and looking like an idiot. I feel like maybe the fast idle cam is stuck or something when cold and after it's all warm another thing is leaking air.
Can anyone on here help me?

Thank you in advance

[haydes55]

I'm guessing it's an issue to do with the choke. It should be an auto choke on that age engine. The carbies might just be filthy, slightly blocked, which would mean with the choke engaged, the engine would rev high at idle, but when the choke is off, the idle is set too low. You could just increase the idle, but that's probably avoiding the issue of a dirty carby.

Back yard carby clean, can you get the bowl off? Disconnect the fuel line. Take off the bowl, spray the shit out of it with carb cleaner, then use crc while moving the slide, put the bowl back on and get the fuel line back into it.

[awayatc]

Carbs arent that hard to work on or work out.....

take of airfilter and see what choke does when cold, and when warm....
Maybe choke doesnt come of entirely....
either sticky, or the automatic part not functioning properly anymore....
usualy a bimetal in thermostat housing with some wires coming of it going to carb activating either choke or fuel enrichment device..
Be brave and have a look

[biketimus_prime]

I'm guessing it's an issue to do with the choke. It should be an auto choke on that age engine. The carbies might just be filthy, slightly blocked, which would mean with the choke engaged, the engine would rev high at idle, but when the choke is off, the idle is set too low. You could just increase the idle, but that's probably avoiding the issue of a dirty carby.

Back yard carby clean, can you get the bowl off? Disconnect the fuel line. Take off the bowl, spray the shit out of it with carb cleaner, then use crc while moving the slide, put the bowl back on and get the fuel line back into it.

Cheers I'll try it out actually. Might be an easy fix

Carbs arent that hard to work on or work out.....

take of airfilter and see what choke does when cold, and when warm....
Maybe choke doesnt come of entirely....
either sticky, or the automatic part not functioning properly anymore....
usualy a bimetal in thermostat housing with some wires coming of it going to carb activating either choke or fuel enrichment device..
Be brave and have a look

I have ripped apart my EFI engines and worked on them heaps. But I just feel like I could mess up the delicate balance of a carb too easily. I'll try it though. Just need some time free!

[haydes55]

Cheers I'll try it out actually. Might be an easy fix







I have ripped apart my EFI engines and worked on them heaps. But I just feel like I could mess up the delicate balance of a carb too easily. I'll try it though. Just need some time free!

You aren't changing jetting or anything. Just cleaning what's already there.... Put stuff back where it came from after you cleaned it. Then just play with the idle screw to get it idling right. Get the engine warm, check idle again, adjust if necessary

[biketimus_prime]

Okay so I think I've found the issue.

The choke butterfly is partially open all the time from cold. Sits like this

When it sits like that, the ute idles high and is warming up.

I managed to simulate what happens when it's warm:
If I move the choke all the way to fully open with my finger, or putting my hand under the carby and using the lever, the engine still runs fine for a few seconds and then starts struggling to idle. Same way it does when I'm driving and come to a stop after the engine is warm. If I let go of the choke it'll pop back into place and everything is fine.

HOWEVER,
*If I hold the choke where it is
*then hold a bit of throttle
*then while holding throttle I let go of the choke and then let go of the throttle, the choke sticks in place at fully open and as I let go of the throttle the engine will struggle to idle.
If I give a good jerk on the throttle, the choke pops back into the partially shut position and the engine comes back up to idling high again.

So it appears when the choke is open as it should be when the engine is warm, the motor struggles to idle.

What's going on?

[haydes55]

The choke chokes the intake. Makes a richer mixture for a cold engine. When warm, it should be fully open. If that action isn't happening smoothly, try going to town on the crc to get it lubed up. If that fails, you'll need to try degreaser or something, clean it up, then lube it. Ideally take it apart, clean it and put it back together.

So if it's idling too low with the choke fully open, adjust the mixture screw with a warm engine running

[biketimus_prime]

Cheers for the tips guys I think I've sorted it. She purrs like a dream now. So I let it warm up and then raised the idle and that seems to have done the trick. Played around with the mixture screw and it only seems to increase in idle if I wind it in but doesn't do much if I wind it out. Either way it seems to have solved the issues I had. I think what may have happened is that the engine had loads of vacuum leaks that I found. The previous owner may have dicked around with the idle screw to solve it rather than fixing the leaks.