M923a2 issues starting.

[Ttallent13]

I’m having issues starting my 1991 m923a2. The truck ran fine about 3 weeks ago. The truck will crank but won’t start. I have a digital voltmeter in the truck. I have 24.4 ish volts before cranking. I notice though that when I flip the starter switch the voltage drops to around 17.4 to 17.6. I don’t remember in the past it dropping that low, I’m not sure what the minimum it needs in order to crank but that seems low. I tested the batteries and they test good but my tester said they were weak. I have them on the charger. Just wanted to see if any other bases need to be covered? Thought I remember reading someplace they need a minimum of 20 volts to turn over, but can’t find that now. Thanks in advance

 

[simp5782]

I’m having issues starting my 1991 m923a2. The truck ran fine about 3 weeks ago. The truck will crank but won’t start. I have a digital voltmeter in the truck. I have 24.4 ish volts before cranking. I notice though that when I flip the starter switch the voltage drops to around 17.4 to 17.6. I don’t remember in the past it dropping that low, I’m not sure what the minimum it needs in order to crank but that seems low. I tested the batteries and they test good but my tester said they were weak. I have them on the charger. Just wanted to see if any other bases need to be covered? Thought I remember reading someplace they need a minimum of 20 volts to turn over, but can’t find that now. Thanks in advance

So it spins over but won't start?

Is the fuel solenoid retracting? Is the manual fuel shut off pulled?

 

[Ttallent13]

So it spins over but won't start?

Is the fuel solenoid retracting? Is the manual fuel shut off pulled?

fuel solenoid is retracting and springs seem strong. The manual fuel shut off is not pulled.

 

[simp5782]

fuel solenoid is retracting and springs seem strong. The manual fuel shut off is not pulled.

Is the fuel arm turned up towards the rear after the solenoid retracts?

 

[Ttallent13]

Is the fuel arm turned up towards the rear after the solenoid retracts?

When cranking it retracts then the arm moves counter clockwise . Then moves back in the normal position when done cranking. Think I said that right.

 

[simp5782]

When cranking it retracts then the arm moves counter clockwise . Then moves back in the normal position when done cranking. Think I said that right.

Ok since it's retracting the fuel valve is opening then you have a supply problem.

Do you have fuel coming out of the lift pump?

 

[162tcat]

Does it turn over at normal speed?
Any smoke from the stack?
What is the outside temp when attempting to start?


Sent from my iPhone using Tapatalk

 

[Ttallent13]

Does it turn over at normal speed?
Any smoke from the stack?
What is the outside temp when attempting to start?


Sent from my iPhone using Tapatalk

Seems to turn over maybe slightly slower. It was around mid 40’s I even plugged in the block warmer just for the hell of it to see if that makes a difference. Just cranks. Will check more stuff later.

 

[Ttallent13]

Haven’t had a chance to work on the truck till this afternoon. At the bleeder screw I’m not getting any fuel I see a few air bubbles when I crack it open and crank over the motor. Im thinking Maybe fuel line might be sucking air

 

[Ttallent13]

I’m going to see if I can find a cracked hose or fuel leaking. I’ll try to pressurize the tank this weekend and try checking for leaks. Any other suggestions?