• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

CAT 3320C slow to start lately

Gary Layton

Senior Member
Joined
Mar 9, 2021
Messages
403
Location
Georgia
sn PAB06638
Engine SN MAE05872
AR No. (arrangement) 2870092

This machine has always started within 3 seconds of cranking the engine.

Last month, I helped clear an old homestead in a newly harrowed field...VERY dusty work for 3 days, sometimes I could not see beyond the cab.

Shortly after that, I was digging out our 70-year-old pond and the engine would stutter sometimes and sometimes just stall. I limped through a couple of days of that and then changed the fuel filter...it only had 246 hours on it, but a neighbor said he had a similar issue before and changing the fuel filter fixed it. My stalling did go away when I changed the filter (the change interval is 500 hours, but super dusty must have been the issue).

I also changed both air filters...internal and outer.

I was away from the farm for 2 weeks. When I returned yesterday, it took about 20 seconds of cranking before it fired up. I ran it for a while and shut it down, and it restarted fine...within one second. This morning, it took about 15 seconds to get it to start up. Later during the day, it would start fine if I turned it off and recranked within about 10 minutes.

At one point, when it had been off about 2 hours, it did not start within 10 seconds. I took the bolt out of the top of the fuel pump and noticed the fuel about 1-2 inches down. I primed the fuel pump, replaced the bolt, seated the plunger, and it started in about 10 seconds.

Is it losing its "prime"? Why is it hard to start after sitting for a few hours? Seems to be some kind of fuel issue.

I did not crack the injector bolt after priming. Maybe that would have made it fire right up?

Once it starts, it runs fine, good power. I expect it to be recalcitrant again in the morning.

What should I be looking for? Would a dirty banjo bolt filter do that? If so, where is it?
 

Deimos

Well-Known Member
Joined
Nov 8, 2024
Messages
220
Location
RUS
It's very likely that when the engine is turned off, fuel from the low-pressure circuit flows back into the tank. The fuel injectors may also gradually begin leaking fuel into the return line.
1774414960857.png1774415205054.png
 

Gary Layton

Senior Member
Joined
Mar 9, 2021
Messages
403
Location
Georgia
Thanks for the input, all. Good things to check...possible old filter residue and those check valves.

It started fine this morning...no priming, within one second. A few hours later, it started stuttering again. I had to prime it and bleed injectors. A few times when it stuttered, I found I could feather the controls and the RPM's slowly came back up...then I could work for 30-45 minutes before it happened again. I assume it slowly re-primed itself, and I could work awhile. I have the CAT tech coming in the morning. He's been a good resource when I reach my limit, so I think he will puzzle it out.

I'll let you know what happens.
 
Top