1971 M151A2 wont start

[Col Batguano]

Hi all, new owner of a 71 M151A2. MUTT will not start, engine cranks but will not turn over. Was running fine a week ago but has not run since. Looking for help please I am by no means a mechanic but want to learn. Lets go through the checklist one by one, where to start I have no idea lol. Thank you for any help. Rob

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[rickf]

First thing is to check for fuel and spark. Take the air cleaner hose off of the carb and while cranking cover the mouth of the carb with your hand. Within two or three revolutions of the engine you should have gas all over your hand and gas running from the carb mouth. No gas means no gas in the carb and you need to pull the fuel line off of the carb and crank it again and see if any gas comes out of the line. Have a can under the line so gas does not run into the alternator. Hint, gas and sparks are not a good combo outside of the combustion chamber. If still no gas and you have an inline filter try again at the inlet of the filter. If still no gas suspect a bad fuel pump.
OK, that is the short version of checking for gas. If you get gas right at the first step then you can skip the rest of the steps and move on to checking for spark. To check for spark, if you have a spare spark plug then take one of the plug wires off of any plug and screw it onto the spare plug. Set the plug on something metal on the engine because you need a ground for the spark. This is usually easier with two people since you need to be close enough to see the plug gap and see if there is a spark so someone else to crank the engine is helpful. Make sure the ignition switch is on and crank the engine while looking for a decent blue spark. A yellow spark is a weak spark and indicates low voltage to the coil. No spark means digging deeper. Do those things and let me know what you find before I hurt your brain any more. If you have fuel and spark then put the plug wire back on the plug in the engine and try starting it with the gas pedal on the floor, it will be flooded from the first test. No choke and full throttle. If still nothing then we will look further into things.
And make sure your batteries are fully charged.

[svramselaar]

hi
a short one and as rick say
take the air cleaner hose of
spray a bit brake clean at the carb and start
wil it run you have feul problem
if not you have no spark

greetings george

[Horst]

Fuel in the tank?
Ignition switch is on (remember that the starter will turn no matter if switch is on or off) ? After ignition switch was turned on, what does the voltmeter read? Somewhere low in the green is good.

Other than that, do what George suggested. That will immediately point you in the right direction.

[rickf]

I don't think I have ever seen a voltmeter that was in the green before starting.

[Horst]

Jeep has been sitting for at least 3 weeks. Batteries are more than 8 years old

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[rickf]

Are they AGM batteries? Mine never last that long from sitting.

[Horst]

Standard wet batteries. But good quality ones. Over the winter period I do charge them about every 2 months, so not very often actually. Over summer time never.

This is the second set since I have the 151, and as you can see it accumulated 7.000 miles since new, 14 years ago I think ?

[Col Batguano]

Thank you for all the help. I will try these suggestions this weekend. What about the spark plugs ? Should I find the plugs need replacing what is best, finding original NOS ones or switch to modern equivalent ? If modern equivalent is chosen do I need to use an adapter ? Thank you. Rob

[Hambone]

The price of NOS plugs has gone crazy, if you want to swap to civy plugs, these adapters will help keep the original look.
https://jeep1942.com/?page_id=9592

[rickf]

I have never seen that type before. I have the original military ones but Midwest Military has these that are built the same as the originals.
I am not to keen on supporting that long tube and the shielded plug wire with a little sleeve nut on top of the plug. Those plugs break pretty easily so sideways force plus vibration is just asking for a cracked plug.

https://shop.midwestmilitary.com/produc ... -m-series/

[Hambone]

They secure down to the plug, never seen one break.

[fowlercal]

Does Anyone know the number of the spark plug that would be equal to the Autolite 2245?

Thanks, Cal

[Hambone]

https://www.sparkplug-crossreference.co ... OLITE/2245

I think Champion J8 and AC Delco 45 are good civy plugs.

[Horst]

thanks for the info in the plugs. I have the adapters but, having one more set of NOS plugs, probably will never need them...

for the original problem of no start, I think it is safe to say that the plugs itself are not the issue. Unlikely that all plugs will fail at the same time.