M38 back fire

maeserik · Post by **maeserik** » Mon Apr 20, 2015 2:24 am

This seems to be a condensor problem !

I had the same problems in the past, the ignition timing became to late at some moments and the engine became very hot. hard to find good condensors these days, therfore i placed the M151 electronic ignition in the distributor and from that moment on no such proplems anymore.

After installing i did not touch it and it stays OK, now already since 2006 !

link :
http://www.g503.com/forums/viewtopic.ph ... f83d81c4c0

Erik

oilleaker1 · Post by **oilleaker1** » Mon Apr 20, 2015 5:07 am

I had a 1976 Ford Truck that sheared the roll pin in the drive gear to the distributor while going down a long hill. The timing went haywire and boom! It blew the entire length of my new 80 dollar muffler wide open. The truck came to rest right in the middle of a highway bridge on a 2 lane blacktop road. When I arrived to find what the problem was, it was raining cats and dogs and I had to sit on the radiator under the hood to stay dry. Upon examining the points, I found I could rotate the rotor anywhere I wanted! You guys reminded me of this one!

John

G740 · Post by **G740** » Mon Apr 20, 2015 5:40 am

Pull the dip stick, smell the oil. If it smells like gas you have found the problem. Very often when the pump starts to go it will cause the engine to backfire on acceleration. Common problem especially after it was running last fall and won't in the spring.
John

ROBCDN3 · Post by **ROBCDN3** » Mon Apr 20, 2015 5:38 pm

Yes Wes. the jeep is all stock and I will pass on the carb. info.

Thanks. Rob.

ROBCDN3 · Post by **ROBCDN3** » Sat May 02, 2015 7:57 am

To all who responded my Buddy pulled the carb cleaned the needle valve and reset the float level. Now he says the jeep does not back fire runs ok but with a bit of hesitation. He is very reluctant to get into the distributor. Thanks to all for your advice. Rob.

Post by **wesk** » Sat May 02, 2015 8:32 am

Did he check the accelerator pump and metering rod diaphragms? I assume based on his reluctance to tackle the military distributor that he is not familiar with the military carb either. You need to confirm the diaphragms are not torn or deteriorated. That the correct spring is behind each one and that the spring is on the correct side of the diaphragm. The illustration in the YM 9-1826A have an error on one spring location. This error was repeated in the 100's of cheap chapter segment copies that were circulated over the years as well. Once you are certain they are in proper shape and configuration then if your hesitation persists go to the distributor and pull the cover off and check for about 15 degrees of free rotation with a quick spring back when you try to rotate the rotor.

Here's the corrected illustration:

The original had the metering rod spring "BB" on the left side of the diaphragm "DD"

Kits often vary a bit. As you can see the significant difference between springs between these kits. Bottom line is beefier spring goes with the accelerator pump.