Hesitation when accelerating

CakeBandit · Aug 1, 2016

Is it normal for the 2.25L 7:1 petrol to hesitate after a cold start, no load? I would like not waiting for 5-10 minutes for the engine to warm up after driving, if I don't she will backfire under the slightest acceleration.

I just adjusted tappets to .010", replaced all the spark plugs (NGK BPR5EGP). I have electronic ignition fitted into the stock distributor. Starts great, no dieseling when turning ignition off.
Checking with the timing light, looks good, but at a higher rpm the flywheel mark wonders around a bit. I got the vacuum gauge out, and put a T onto the vacuum from the zenith to the distributer. When I quick accelerate the vacuum goes to near 0, then shoots up. Is that normal? Other then that the vacuum is steady at steady rpm's, no drifting. Anybody know if this a carb issue, or vacuum advance on the distributer? I hope its not the chain.

Blackburn · Aug 1, 2016

Where is your vacuum advance attached to engine?
Should be on Carb not manifold if I recall correctly.

John S · Aug 1, 2016

It's the carb.If it's back firing it could be a blocked or dirty idle jet. What kind of carb?

John S · Aug 1, 2016

Vacuum advance goes to the carb via connection with engine breather pipe. Check that for any leaks or split pipes.

CakeBandit · Aug 1, 2016

So you guys are saying that you can run out out to your Landy right now, cold start it, and haul ass out of the driveway without the engine popping and quiting?

lol
Checked the vacuum hose for leaks, checked the distributer vacuum diaphragm for leaks- all good.
I have had the Zenith carb dis-assembled many times in the past. In fact I just had it dis-assembled 3 weeks ago. Had a leaky float once, and had to lap the halfs 3 times dealing with the "zenith warp" in the past. I have adjusted the float hight in the past trying to solve my problem as well. This problem about hesitation is a long on-going problem I have had since I bought this truck.
The vacuum hose goes from carb (Zenith) to distributer on mine.
Thanks for the replies.

Blackburn · Aug 1, 2016

The position on the carb changes the advance in relation to throttle position ie vacuum reduced at full throttle from memory.
are the distributor mechanical advance weights lubricated , also is the small felt plug above them in end of distributor shaft lubricated.
An aquaitance could not get his to run properly till he lubricated that felt plug!

John S · Aug 2, 2016

CakeBandit said:
So you guys are saying that you can run out out to your Landy right now, cold start it, and haul ass out of the driveway without the engine popping and quiting? lol
Checked the vacuum hose for leaks, checked the distributer vacuum diaphragm for leaks- all good.
I have had the Zenith carb dis-assembled many times in the pastIn fact I just had it dis-assembled 3 weeks ago. Had a leaky float once, and had to lap the halfs 3 times dealing with the "zenith warp" in the past. I have adjusted the float hight in the past trying to solve my problem as well. This problem about hesitation is a long on-going problem I have had since I bought this truck.
The vacuum hose goes from carb (Zenith) to distributer on mine.
Thanks for the replies.

Basically yes. I've recently serviced the ignition and carb after exactly same symptoms. Dirty idle jet was the actual problem. I have a Weber carb.

CakeBandit · Aug 2, 2016

ok I will try the above: distributer- lube the shaft and springs, check for the piece of felt and oil it.
If that doesn't work I will find out where the idle jet is in the Zenith, make sure its the right jet, and clean.
Thanks for the suggestions.

dominicbeesley · Aug 2, 2016

Are you sure it doesn't need a bit of choke. A normal landy (with a direct fan) won't warm up until it's been driven a bit

Mark Hillier · Aug 2, 2016

have you thought about a new carb and inlet gasket as carbs wear out as you have lec ignition and have you replaced the plugs and
given it a compression test

Hesitation when accelerating

CakeBandit

Active Member

Blackburn

Well-Known Member

John S

Well-Known Member

John S

Well-Known Member

CakeBandit

Active Member

Blackburn

Well-Known Member

John S

Well-Known Member

CakeBandit

Active Member

dominicbeesley

Well-Known Member

Mark Hillier

New Member

Similar threads