# CAT won't start - runs rough



## Snaaar (Oct 29, 2006)

Several months ago, my CAT 247B starting running rough. Priming it would help for a minute or two, but then the problem would return.

This machine will not start when the temperature falls to the 20's or below - the glow plug cold assist switch does not help. We have to remove the air filters and give a tiny puff of starting fluid - inconvenient to say the least.

Is there a place on the machine to bleed any air from the fuel system? Also, I can't seem to find a way to plug into an electrical outlet to heat the engine.


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## harley hauler (Nov 20, 2003)

let me talk to my dad, he works for cat I'll get you the info you need:salute:


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## CEPropertyMgt (Dec 31, 2007)

once the cat is running you need to bleed the injecters. look for the fuel tubing lines coming from the fuel control. bleed the main feed from the fuel control first, then each individual line coming from the fuel control. you want to do this by loosoning the nut on the line (nut furthest from the fuel control/closest to the injecter) just enough to where the fuel just spits out of the nut. do this to get the air out of each line. make sure you do prime the fuel control first. although, in cold weather we usually plug in the heaters to help starting. otherwise you will need a shot of ether if your manifold heat or glow plugs arent working.


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## Milwaukee (Dec 28, 2007)

DId you check that diesel not become gel???


My boss alway put diesel additve in diesel during winter if it run bad he let run until it improve if not then he stop and open those nut on injector pump then try now it work but very much smoke like white with blue.


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## powerjoke (Nov 13, 2004)

Snaaar;492822 said:


> Several months ago, my CAT 247B starting running rough. Priming it would help for a minute or two, but then the problem would return.
> 
> This machine will not start when the temperature falls to the 20's or below - the glow plug cold assist switch does not help. We have to remove the air filters and give a tiny puff of starting fluid - inconvenient to say the least.
> 
> Is there a place on the machine to bleed any air from the fuel system? Also, I can't seem to find a way to plug into an electrical outlet to heat the engine.


it is not getting fuel delivered to the inj pump ie bad fuel filter or poss a little bit of gel.

i never put additive in because i buy fuel that has it in it already but if i have a problem i just thin it with a little gasoline, maybe 1 gallon to 30 gallon will do the trick

i would change the filter first, and i think there is a sediment bowl just inside the rear door



CEPropertyMgt;493416 said:


> once the cat is running you need to bleed the injecters. look for the fuel tubing lines coming from the fuel control. bleed the main feed from the fuel control first, then each individual line coming from the fuel control. you want to do this by loosoning the nut on the line (nut furthest from the fuel control/closest to the injecter) just enough to where the fuel just spits out of the nut. do this to get the air out of each line. make sure you do prime the fuel control first. although, in cold weather we usually plug in the heaters to help starting. otherwise you will need a shot of ether if your manifold heat or glow plugs arent working.


this would be correct if the mashine wont start, but it does,

BTW if a motor is running there is no need to loosen all the lines, if we run one our i just crack a couple of the easy to get to lines until fuel spray then tighten them back up and it will run on 2-3 cyl for half minute then it'll pick up the rest of them


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## powerjoke (Nov 13, 2004)

harley hauler;493071 said:


> let me talk to my dad, he works for cat I'll get you the info you need:salute:


now this is a good post


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## pinepointe (Jan 3, 2006)

first off never cut ur diesel fuel with gas, never. you can however cut it with kero. I have had the same trouble with a 939 loader. I eventually trace the prob to a piece of dirt that was clogging the screen in the fuel tank. I emptied the tank and blew the lines out, primed the system and it is 100%


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## powerjoke (Nov 13, 2004)

pinepointe;493450 said:


> first off never cut ur diesel fuel with gas, never.


why? i have been doing it for YEARS,

and yes i have experiance  o.h. and i have a 939 too but mine is a C seriesII hydro and yes i have even done that trick in this machine


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## powerjoke (Nov 13, 2004)

Snaaar;492822 said:


> the glow plug cold assist switch does not help.


you have to push it and hold it in for 30-45seconds


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## TL697 (Jan 19, 2008)

I recently had exact same problem w/ my 257B...

I changed the Diesel filter/water seperater... $22 at NAPA

Runs like new...

I had been using diesel conditioner, priming, etc, but finally got to the root of the problem.

my $.02


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## CEPropertyMgt (Dec 31, 2007)

we had a problem with one of out cummins 855's, hard starting, we bled the injector lines as i described in my previous post and did remove a little bit of air from the system. this did make it easier starting and smoothed the idle out. on one of the other loaders, we blew compressed air thru the fuel line back into the tank. had some buildup on the screen inside the tank. did that and ran the loader till the talk was almost empty (100 gallons) and cleaned the inside of the tank. had about 1/2 inch of sediment on the bottom. 

not sure if your cat has a filter inside the fuel tank, ours had on there(inside) and a prefilter and regular filter in the engine bay. 

one of our cat excavators, we would have to occasionally clean a small screen which was located in the feed line to the fuel control. 

good luck, i would come out and help you if you were closer.


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