New Holland 3930 won't start

   / New Holland 3930 won't start #1  

ErekN

New member
Joined
Apr 19, 2017
Messages
6
Location
Blountville, TN
Tractor
1996 New Holland, 3930
Hi, I have a 1996 3930 (3 cylinder) that I've had for aroubd 4 years. I rebuilt the engine a year ago bc of excessive blow by. Last week, it died on me backing a trailer up a hill and wouldn't restart. I discover that the fuel tank was blocked with crud. Drained tank and out new fuel in, but it still wouldn't start. Seemed to turn over real slow. I towed it to the barn and decided that since it's 20 years old I'd take the pump and injectors in to be checked. Pump was rebuilt with a new transfer pump and metering valve and the injectors got rebuilt as well. Got it all back together and it still won't start, although now it seems like it almost will but just not quite. My neighbor pull it and we got it to run on its own, but really poorly and didn't want to cause any damage. Does anyone have any advice as to what might be my problem? The pump is a dpa style and all of the marks were aligned on the gears and it has a key/slot that can only go in one way.

Thanks in advance,

Erek
 
   / New Holland 3930 won't start #2  
By reading your post, it sounds like you are not a novice. So, I'm assuming that you tried cracking open the injectors. When you said that it runs, but not well, how would describe it? Is it out of time, or not running on all cylinders, etc..
 
   / New Holland 3930 won't start
  • Thread Starter
#3  
I did crack the injectors and that didn't help. Unfortunately I don't know what it should sound like when it is out of time. My neighbor thought it sounded like it was only running on two cylinders. I have a fair bit of experience on this tractor with the help of a friend who is a helicopter mechanic but not much with other tractors.

Thanks
 
   / New Holland 3930 won't start
  • Thread Starter
#4  
I just pulled it down hill again and got it to start. It would barely run and when I unhooked the lines to the #2 and 3 cylinders it still barely ran. So looks like it was just running on the #1 cylinder. I'm stumped.
 
   / New Holland 3930 won't start
  • Thread Starter
#6  
Sorry. I forgot to mention that I replaced that as well
 
   / New Holland 3930 won't start #7  
Do you have the 3 piece filter head?? the filter is sandwiched between the filter head & a base w/ a long screw in the center??
You might have put the top gasket ON THE FILTER.. BIG no no.. it chokes off the fuel.. the oring goes UP IN the filter head, NOT ON the filter.. Give it a try & let us know what happened..
 
   / New Holland 3930 won't start
  • Thread Starter
#8  
Thanks for the advice. That wasn't it. I did put the rubber gasket in the groove of the upper housing.
 
   / New Holland 3930 won't start #9  
I'm going to assume its a CAV DPA injection pump?? IF you had a bunch of crud in the tank, chances are good it made it to the pump inlet.
There is a hidden plastic filter under the fuel inlet nut on the inj. pump.. you remove the nut, the big spring & hold the guts down w/ a small screwdriver & w/ a 90* pick, reach in & pull up on the filter.. MAKE SURE you hold the inerards down w/ a screwdriver.. if they come up, your in trouble..
 
   / New Holland 3930 won't start
  • Thread Starter
#10  
Bad news for me. It looks like a blown head gasket. Pressurized air will pass between the cylinders with the valves closed. So I'm going to take off the head and see what it looks like. Pump wasn't the problem to begin with. Oh well.
 
 
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