L20B backfiring

[banzai510(hainz)]

I see n people wire in eleltric fuel pumps by wire into the ignition wire(blk/white wire) This is wrong.

 

 

if you have a loose fan belt this can do it also as you go up in speed the current load increases on the ignition side and yiu draw to much from other sources it will cut out.

 

 

a voltmeter will catch this and you can narrow what is mayjor draw in your system.

Get the one that plugs in to the cig lighter. with the digtal readout. cheap.

Even the stock low out put alt should not cause it to do this unless its going bad.

 

 

Napa can load ck alternators if they have the right machine/load cker type.

[moparvwfreak]

I'll check the belt tension as its been a while. Haven't checked it since the motor went in. As for an E pump, don't have one. So I know that's not an issue. :) I will also have the alt checked again before swapping it out.

[Rockman1]

On 4/17/2010 at 1:03 PM, banzai510(hainz) said:

most time to me its been worn out ignition that has been a killer in power(backfiring)

worn dist shaft bushing, (if points) worn out points or bushings(side to side play in dizzy shaft) condensor or condensor grounding.

 

if motor looses a cylinder its a lash pad fell off. adjust all the lash .

 

 

I havenet changed a distributor cap/rotor in over 5 years on all my datsuns. Most have been worn out dizzys!

I am now having the same issue with my 620 the bushing on the distributor have worn out. (Constance point gap change) I can't seem to find replacements bushing. And am not going to pay 250 dollars for a new one when you can buy bushing for 12 13 bucks if you can find them. the size is 12.5mm x 16mm x 15mm or close to that.

[datzenmike]

Brass? have a machine shop make you one. A lot less than $250. Talk to the machinist, maybe he could make you one on a weekend or after work for a case of beer.

[banzai510(hainz)]

somebody has to have a spare dist in a box you can have,  you dint mension the motor as 620 had different motors and the dist mount could be different between the years and cap size.

I would swap the condensor first in case. But you know if the bushing has side to side movement and faster you go the worse it gets driving

 

I seen thse on Amazon and Ebay .Make sure to get the clip on version as shown. As I seen screw down cap version for L motors and assume its not a Nissan cap unless from a J motor also the timing plate and mount might be differet than yours. this dist is a point conversion so you use the stock coil and ballast resisitor. I havent tried this so your on your own.

 

.https://www.ebay.com/itm/403714993747?hash=item5dff49ee53:g:yAUAAOSw8LNg36Yx&amdata=enc%3AAQAIAAAA8Icv%2BB6Ae%2FLzePQIKy1L1A4vrDGwAqF3cAR9aSBO0AEgaYH53zYKhHI7v7L9ZLTWDelCg5YNqa7zzt3hF1MIbevOAkk%2FkOk6vwvM7s56RZM%2FF4cCoCrrAAn8%2FNyUFqr2z9ST1bVIMhlucDhACWxqBSfTl3uTbdmi13wIuAKTnc5vNYMqvzKOPugV5Yis0BIdOvshHkdgeA0OHawGeSTTN32qg4yz9CWmCb3Egoo0hAkRqLG1vhQbQuqjGw77wdSgtXys6e%2Bt4KlIsfdxbtusMCx%2BIdr27bN%2Bb8Vd0kbwuDfj32tEzkoUKKG8Uz9Eg3NSlQ%3D%3D|tkp%3ABk9SR6rvw8jkYg

Edited October 12, 2023 by banzai510(hainz)

[datzenmike]

Initially this backfire was out the exhaust and only on deceleration. Don't see how the distributor causes this but not at other times.

[banzai510(hainz)]

put a timing light on there. see if eratic . mostly likely not at idle.

 

do a wiggle test with POINTS  closed. if it opens when you push slightly sideways then the coil will fire when POINTS open

[datzenmike]

The distributor won't know if accelerating or decelerating only RPMs. Why not all the time?

 

There is an emission part on the L20B called an anti backfire device. It's only operates on hard deceleration.