1983 720 Z24 Power Issue

[datzenmike]

I'm assuming that it's using fuel under load faster that it can be put into the carburetor. This is the point of that driving test. If it's sucking the carburetor dry under load then that's the problem and it can be fixed.

 

The float inside must be adjusted slightly higher so the fuel level has to rise higher to shut it off. Half way is correct but if just under half it should still run. Another possibility is the inlet needle valve is partly plugged or the fuel screen under the inlet banjo fitting is dirty, pump not putting fuel out fast enough, partly plugged fuel line. Could be many things but at least it will be narrowed down to fuel delivery. .

 

Take it for that test drive. This will show once and for all if it's running out of gas or not.... and you don't have to take anything apart.

[AustinSink1]

I think I am just done messing with it. I'm going to order a weber carb next week. I appreciate all the help!

[banzai510(hainz)]

Order fuel filter first and change.

then order carb

 

Did this start after the  dist swap? 

[AustinSink1]

Fuel filter has already been changed, as well as all fuel lines due to having no fuel tank pressure. Changed the distributor and adjusted timing about 2 months ago. Been driving good since, just slow but it ran great. Once I manually pushed up on the second barrel after starting this thread, these issues have started. But prior to making my thread post the truck ran great just lack of power.

[banzai510(hainz)]

So it ran slower when the distributor was changed? or was slow all the time.

 

i don’t know the Z series moto but on L series there was a 2 late model distributors and if when gets the wrong one from Vatozone the mating plate mount hole was like 20 deg a off so one can make it run but after one goes the dist would go out of time.On L motors one can adjust the timing plate the bolts under the distributor housing and you can adjust that besides the obvious timing slot that most people adjust. So one can adjust down to zero and up to say 20-25 deg (at least for a L motor)

 

make sure the dist cap isn’t cracked but I’m only guessing now

[datzenmike]

 Pushing up on the second barrel was BECAUSE of lack of power not the cause of it. This was to make sure the secondary was free to open.

 

 

You're going to spend $300 on another carb when it may just need a float adjustment?

[AustinSink1]

Yeah so it ran slow before. But vacuum advance on distributor was bad, so I just replaced the whole thing, which helped a little bit but still pretty slow. Timing was adjusted with timing light to 5 degrees at idle. The guy that helped me do timing and adjust carb a bit is very experienced with carbed engines. He helped me replace the distributor as well and fix all my vaccum leaks. So everything was theoretically in perfect working order. My guess is that something with the secondary is messed up. 

[AustinSink1]

Datzenmike,

 

I tried adjusting the float, it was quite off, but I set it to the measurements specified in the Haynes manual and is still low on fuel. Should I try setting the float even lower? 

[datzenmike]

I think it should be adjusted higher. I think the setting (called float drop) is with the carburetor upside down which isn't practical. Lift up gently with a pencil and the needle valve above it should be just closed with the float level. Get the fuel in the middle of the glass and it's correct.

 

Vacuum advance has no effect on high speed or heavy load. It affects part throttle.