Weak Spark / No Start

[dunebuggy1234]

I drove by 1972 beetle / dunebuggy around today, and it started up perfectly and i drove down to the store for a new airfilter. when i went to start it back up, it fired up right away and idled for a while. but just when i was about to go, the RPMS dropped and fluctuated and then it died. now it wont start back up. spraying a little bit of starting fluid seemed to help a little bit, but it didnt always respond. i am getting fuel to the carb. I had a buddy check the spark, and it was a pretty weak spark. the battery was charged and hooked up to my car. does anyone have any idea what would cause a weak spark. and starting fluid doesnt seem to work anymore.

[David_nc_72std]

Electronic ignition, or points & condenser?

[Cusser]

Check the points gap, maybe the running block/distributor cam wasn't lubed and it wore down, so points are not opening.

If you have a pointless ignition, suspect that.

If spraying aerosol starting fluid into the air cleaner doesn't help, then it's a sparking issue.

Disclaimer - I must warn you: I got an infraction today on a truck board for being "to the point".
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[dunebuggy1234]

I do Have an electronic ignition. it is pretty much brand new, but sometimes that doesnt mean too much. is there a way that I can test if that is the problem for sure? I dont have a back up. All other fuel system and ignition parts are new. also I tried to start it today and adjust the timing, and it started, but then died shortly after unable to start it up again.

[VW_Jimbo]

What is the voltage getting to the coil from the key?

Do a good visual inspection of the cap, rotor and wires. Look for small (tiny) black spots. You will need to remove the rotor and look up into the open port which the distributor shaft goes into. Sometimes a rotor will have a burn through able to be seen at that point.

If all checks out, do a spark check at the plugs. Is the spark good?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[ashman40]

[dunebuggy1234]

my plugs on it are the Stock B5HS NGk plugs
the Coil is a Napa IC64SB. I Actually don't think i got the one with the resistor
the plug wires are Bosch 09001 from Napa
and the distributor (including cap and rotor) are Part #REPV314108 from carparts.com

I don't know if that will help you guys any.I am just confused on how it ran so perfectly and then die out of nowhere and refuse to start.

[dunebuggy1234]

it started up just fine today, but just like last time it shut off and now it wont restart. I am just overly confused on what is happening

[ashman40]

[dunebuggy1234]

the coil is testing at pretty much 4.0
testing from the center of coil reads 8,600
the rotor measured to be 1.07

[ashman40]

[dunebuggy1234]

i have compression, i can feel it when i turn the motor
i have fuel I can See it in the carb, and it doesn't start with starting fluid
i put a brand new coil on there today from duralast/autozone
plugs got put on yesterday from ngk (B5HS)
the wires are pretty new
and the cap, rotor and distributor are all new.

I am losing my mind over this. on paper there is no reason that this thing should not run. i don't have any help to turn the key and check for spark. i tried to turn the motor by hand like that trouble shooting guide said to test for spark from the coil, either i didn't turn it fast enough, or there is no spark getting to the cap

it started right up this morning with out an issue, but will not even think about firing up now.

and it all ran perfectly just a couple of days ago, I drove it for almost 2
hours with out a single hiccup. if there is anyone in the southern Indiana area willing to lend a hand, i would gladly do what ever i can to help, I am just confused on what could cause this

[dunebuggy1234]

i was able to talk my friend in to coming to help me. I get spark at the distributor and all the way down to the plugs, the spark at the cap is nice and blue. the spark at the plugs are a little yellow though. So what does that mean? I tried to spray starting fluid in the carb while my buddy was turning the engine but that did nothing at all.

[richardc]

One thing you can try,remove coil wire out of distributor cap, remove cap off of distributor, with insulated pliers hold coil wire about 1/4 inch above rotor while you have a buddy crank engine, spark should not jump to rotor, if it does rotor is bad. GM techs back in the late 70s will know what I'm talking about.
_________________
1970 Ghia vert
1970 Beetle sedan

[VW_Jimbo]

[VW_Jimbo]

[ashman40]

Since you mentioned the spark from the coil wire is strong, but the spark at the end of the plug wires is weaker (is this for all four plug wires?) try this test...
Remove one plug wire from the distributor and connect it to the ignition coil. Crank the engine and test for spark at the end of the plug wire. Is the spark strong? If so, it is the rotor and distributor cap causing the loss of spark strength. Get a new pair of cap and rotor. If the spark is NOT strong using the plug wire... get new plug wires.


TIP: if you have an alternator with a B+ stud. The voltage at this stud/wire is battery voltage. Run a 14AWG wire from the engine compartment to the #50 terminal of the starter. You can pass the wire thru the reverse light wiring hole in the firewall tin. Make sure there is a way to cover the end of this wire when it is not in use or you risk it shorting out when you crank the engine. I used a female crimp on terminal with a cover that would slide up/down to cover the terminal when not in use. Also make sure it doesn't get sucked into the fan intake.

Now when you have no buddy (nobody) around to help you crank the engine... place the car in neutral and set the parking brake. Turn the ignition key to ON. Touch the end of the #50 wire you installed to the B+ stud on the alternator. The engine should start cranking and eventually start. Be careful of the fan belt!
This is a "poor man's" bump starter switch.
If you want to spend the $$ you can buy a proper bump starter switch and leave it tucked away in the engine compartment. This is a bit more risky as it makes it even easier for someone trying to steal you car to crank the engine to get it starter w/o the key. The starter switch is obvious. A loose wire not so obvious.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[dunebuggy1234]

I went out today and to try to start it, after moving the distributor a bit ( the timing seemed to be off) it started up perfectly, it idled for about ten minutes, I was able to rev the engine very smoothly so it seemed there was no misfire or anything of the sorts, and then it started to idle erratically and then died and wont start up again. that has happened the last 3 days in a row.

I am able to start it right up in the morning, it sputters out, then it dies and i am unable to get it started again.

it is confusing because all of the test i have ran seem to come back positive and when it does start, it runs perfect. has anyone ever heard of these engines doing that? running perfect and then dying without being able to start back up. its almost like something overheats and takes a day to reset, but I just don't know.

this isn't just a no start issue.

I only tested 2 of the plugs one on each side, they both were pretty much the same. a little bit of blue and yellow.

I will try that test to see if it the cap and rotor or the wires sometime soon though

[dunebuggy1234]

the idle doesn't really fluctuate as I stated earlier. the engine just dies off. I was able to start it again only for it to die off almost immediately even while I was pressing the gas. I started it back up about 3 times until it wouldnt start up again

[ashman40]

Once you have reached the point where it no longer starts, remove the screws that hold the top of the carb down. Pull the top off being careful not to damage the gasket. How high is the fuel in the fuel bowl. Stock Solex carb should maintain fuel around 3/4" from the top of the bowl. If your fuel level is much lower than this, you have a fuel problem.
A common problem with mechanical fuel pumps is the case will get hot and constrict the block that the pump sits on. This constricts the push rod that drives the fuel pump so the pump stops working. If you try to remove the block and check it for friction the case and block will quickly cool and your will never find a problem. As a preventative measure, use sandpaper and grind the outside of the part of the stand that slides into the case. Make sure there is lots of free play around it so as the case heats it does NOT squeeze in on this part to pinch the rod. See if that makes a diff.

Replace the carb top and try to crank the engine once more. If it still doesn't start, pull the center distributor cap wire and check for spark. Replace it and immediately test one of the plug wires. Is there still a spark??

Both of these are testing the condition of your fuel and spark at the point when your engine is NOT running. This was when Speedy Jim's troubleshooting steps should be run. If your engine starts fine in the morning his steps will likely find nothing wrong.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}