510 just got towed home again

[ricky]

hey guys so the 510 has been towed home for the 3rd time since i got it lol. still love the car just wish it would stay running for more the a few months. any way heres the deal car has been running great since i put the l20 in it. today i was driving some where and it was running fine then it just started cutting out kinda like it was running out of gas. (yes it has gas). i can get it to idle but its like it is running on 2 cyl. pulled plugs and 2 were black as hell and other 2 looked great. i put new ones in and runs the same checked spark and all that good stuff. i have not checked for vacuum leak yet which i think could be part of the issue. but i suspect float is stuck open. i have a clear fuel filter and it is normal a quarter to half full all the time but now there is barley an air bubble. i can see gas in side the intake below the carb pooling there. so i pulled fuel line off and ran it. when the bowl was almost empty the idle sounded normal again then it ran like crap untill it ran out. also the gas pedal dose almost nothing at full throttle it idles slightly above normal idle. fuel pump is working. i have a spare carb i will throw on tomorrow. just wanted to see what you guys think if i need to give better detail let me know. i have been looking on here for similer problems but nothing seems to match. if any one has a link to a thread that could help that would be great to. oh and both carbs i have are weber 32 36

[izzo]

throw that spare carb on there and see what it does. Might be a vacuum leak, dunno tho. Do free tests before throwing any money at it. its running a single carb right? if the other carb doesn't make it any better, double check for vacuum leaks, maybe run a compression test on it.

 

Get it to run/idle decent with current carb if you can, and spray some brake cleaner aroudn the base and see if it does anything. probably not tho... points or matchbox?

[ricky]

Match box. I can get it to idle but not well I also messed with timing to just to see no difference

[banzai510(hainz)]

if its running on 2 cylinders then pull a plug wire and if nothing changings then yeah your not running on that cylinder. If you pull a wire and it gets worse then you knwo the cyl is firing.

 

If cylinder is not firing ck plus but most like could be a lash pad fell off a rocker or a rocker is too tight.

 

then swap a carb.

 

if you put a electric fuel pump with no regualtor this could have wore out the needle valve or or is over powering the needle valve or try a regulator.

 

 

I have only run USED webers on my Datsuns and never had a real proplem with them except plugged idle jets.

[ricky]

It's a manual fuel pump. What if it runs better when you pull a plug? I pulled valve cover I have not checked valve lash yet but every thing looked good I thought maybe broken spring or something but I will check valve lash. Do you have picture of a lash pad. Not sure what that is

[banzai510(hainz)]

lash pad is at the tip of rocker arm.

to make this simple I turn moto till the cam lobe is pointing up and if the rocker arm wiggles then the valve is fully closing which is good.

 

for the staement you pull a plug wire and it runs better isnt going to happen. Do this ck first.

 

 

ck the cylinder firing , then I guess its the carb cause you have a Matchbox in there for last time. Just ck to make sure its grounded good

[ricky]

Ok thanks I'll update as I go

[H5WAGON]

Make sure your spark plug wires are good......switch a few wires and see if problem is the same....:unsure:or test with ohm meter.

 

Wires can not be judged on looks alone......How about the cap and rotor?

 

Double check firing order (Duh)......Good luck.

[ricky]

Just got new cap rotor wires and plugs I needed them anyway so I'm going to put them check valve lash and go from there

[ricky]

hey guys is there a way to test the box on side of match box dizzy

[HRH]

Yes, take the ignitor unit to your local NAPA or other parts store. They should have a machine to test ignition control modules, that's what the matchbox is.

 

Have you changed your plug wires recently? Are they good quality? Does your cap and rotor look okay? Are there any carbon trails inside the cap, i.e. misfirings?

[ricky]

Ok so I swapped carbs no change. Cap rotor plugs wires and coil are new. Fuel is good valve lash is good. Im getting spark but it seems if I pull a wire off the plug it seems to run better like the 3 others are getting better spark.

[pocket rocket]

90% of all automotive electrical problems are related to the grounding/earthing. check/clean all the ground wires on your motor.

 

 

What did you gap your plugs at? If the gap is too large the spark won't be able to jump it. Try closing all the plug gaps up 0.005" and see if it gets any better. When you replaced the plugs, did you get the correct ones (seat style, heat range, projected or standard core?)

 

If those don't fix it, I think you need to start looking further. Start with the basics;

 

Check you have the plug leads on in the right order (correct firing order), as someone else mentioned. Pop the cap off the distributor & bump the engine over so you can see for sure which way the distributor is rotating.

 

Check fuel filter - is it clean & around the correct way.

 

Check your fuel lines & fuel pick up (you mentioned earlier that you think it might be running out of fuel).

 

 

compression and/or leak down test - this will tell you the condition of rings & valve seal

 

roll motor over to TDC on #1 on compression stroke, check both valves are closed. Check another cylinder the same. This should tell you if the cam timing is out - might have a stretched chain or the tensioner might be bad.