M923 with Peculiar cold start

[Doubled]

1984 M923 with a NHC 250 cold start only at 70 degree temps.

Starting engine with out depressing accelerator engine starts right up but dies. After it dies you have to crank it quite awhile before it will re-start. Once it re-starts it acellerates just fine.

Starting engine and you hold the accelerator down the engine will run at a slow speed very sluggishly for a few seconds then slowly die. It will crank for short time then re-start and accelerate normally.

None of my other NHC 250's do this quite this way. They may be sluggish and spit and snort for minute but don't die. On my 818's I use the pump since its on the dash


Is this a sign of a problem or should I be using the pump even though its under the hood?

 

[wsucougarx]

Have you changed out your fuel filter? Sounds like you may have air in your lines via air leak. The culprit can be anywhere but I'd check the fuel filter gasket to make sure she's fully seated and not introducing air into your system.

 

[Doubled]

Have you changed out your fuel filter? Sounds like you may have air in your lines via air leak. The culprit can be anywhere but I'd check the fuel filter gasket to make sure she's fully seated and not introducing air into your system.

I will try that thanks!!!

 

[goodguyzy]

The primer pump seal can have a tiny leak and let air in.

 

[EMD567]

Air Leak............Either the fuel filter or the flexible hose to the IP.

 

[Doubled]

Thanks Guys!!! I will get on it tomorrow and see what I can find

 

[Jesse6325]

What they said, Sometimes the leak is small enough to not leak fuel but just enough to suck air, Guess how I know.

 

[Truckoholic]

Yep, I was gonna say air leak as well. That sounds just like what my M813 was doing when there was a hole in the fuel line where the clutch pedal linkage was coming in contact with it.

 

[fsearls92]

Mine started doing the same thing. I know its air getting in the fuel lines, because I can see bubbles in the clear line by the primer handle.

 

[M35A2-AZ]

Sounds like an air link and/or Prime problem.
Good luck with it. I feel your pain. My M923A1 had a fuel problem and it turned out to be the pickup tube in the fuel tank.

 

[Doubled]

Just wanted to report back.

I rigged up a way to pressurize the fuel tank with 10PSI and found two leaks. There was a tiny pin hole in the plastic line to the primer pump and the bolt in the top of the fuel filter was leaking. It had an O ring but the washer was turned and wasn't dropping down in the Square recessed area. The truck starts right up now.

Thanks for all the useful information!!!

 

[Neophyte]

Mine started doing the same thing. I know its air getting in the fuel lines, because I can see bubbles in the clear line by the primer handle.

Primer handle? I'm having a similar starting problem with my 925 (even slaved it to my 817 as batteries gave out)......but not sure of a primer handle (i.e. my namesake, Neophyte.....new beginner) on the 925. The OEM ether seems to give the engine a bump, though not enough to start when freezing (and it starts right up when over 45 degrees....no ether needed). I can start after about 5 minutes of cranking (intermittently in 10 second intervals).....but can't be good for the starter.

Cold starting idea's for the 900 series truck? Magnetic block heater? I have had no issues starting except when cold (and a little nervous pumpin the 3 second shot of ether into the engine more than once while repeting start cycle)