cat c12 trucker

Bridgetown, Barbados

#1 Jun 13, 2010
hi there i have a cat c12 in an international engine hard starts and when it starts it misfires up to 1500rpm then revs clear to 2120rpm can any one help me with my problem.

Since: Jul 08

Location hidden

#2 Jul 11, 2010
sounds like air in fuel. or it could be an issue with the timing sensory circuit fex. a failed secondary speed/timing sensor. does the engine dashligh indicate any faults?
pwbent

Brisbane, Australia

#3 Dec 16, 2010
disconect crank shaft sencor then try to start should be fin then
pwbent

Brisbane, Australia

#4 Jan 18, 2011
replaced crank sencor on c12 replaced engine harness still wont start with crank sencor pluged in unless i use a bit of aerostart runs fine then. runs an starts fine on cam sencor alone plug crank sencor wont start doing my head in help
Nick Brown

Perth, Australia

#6 Nov 21, 2011
Hey Just let you all know i fixed it today. The Auto sparkys had put a new plug on the engine harness side for the crank angle sensor and had the wires swapped around in the wrong positions in the plug. It was getting a good speed signal and not throwing any codes also the wires had faded or were different colours to the schematic so allof that made it hard to find but all sweet she is alive again
mick

South Bend, IN

#7 Jan 26, 2012
have a c12 with a miss, my local mechanic replaced
a injecter and said the cam needs replaced. can you tell just by replacing the injecter or should i get another opinion
Ken

Marion, IN

#8 Feb 26, 2012
mick wrote:
have a c12 with a miss, my local mechanic replaced
a injecter and said the cam needs replaced. can you tell just by replacing the injecter or should i get another opinion
I'd definitely get a 2nd opinion, unless you watched the 1st mechanic physically measure the lobes on the camshaft, checking the dimensions. Occasionally a camshaft shows enough "visible wear" to see that it's bad without measuring it. Have you looked at it yourself?
happy go lucky

Bowie, MD

#9 Feb 29, 2012
Have c12 runs great except when it gets warmer outside. Then it will chug(miss?) Only when warmed up and only if I shift quick.if I keep on the fuel it continues to chug(miss? If I let off then slowly apply fuel it clears up.once it clears up I can step on it with no problem.when this happens it does not throw any codes.any ideas.
trc

Stockton, CA

#10 May 4, 2012
just had a cat c12 rebuilt inframe done.
only getting cold air in cab and bunk when i turn on heat.
do i need to turn the brass valve on the hose coming from radiator to get heat?
or is it a different issue?
Ken

Marion, IN

#11 May 5, 2012
There should be two or three brass valves located on the passenger side of the engine, and there will be 3/4 inch heater hoses connected to them. Normally one controls the front heat, one for the bunk, and some engines have a third one, which heats the fuel tanks!
trc

Stockton, CA

#12 May 5, 2012
Wow, thanks so much Ken. I'll check it out.-Ted aka "trc!"
trc

Stockton, CA

#13 May 6, 2012
Ken wrote:
There should be two or three brass valves located on the passenger side of the engine, and there will be 3/4 inch heater hoses connected to them. Normally one controls the front heat, one for the bunk, and some engines have a third one, which heats the fuel tanks!
Ken - Go to the head of the class. You solved my problem. Thank you so much.-Ted
Ken

Marion, IN

#14 May 6, 2012
trc wrote:
<quoted text>
Ken - Go to the head of the class. You solved my problem. Thank you so much.-Ted
You're quite welcome...Happy Trucking :)
rjb

Sydney, Australia

#15 Jan 21, 2013
happy go lucky wrote:
Have c12 runs great except when it gets warmer outside. Then it will chug(miss?) Only when warmed up and only if I shift quick.if I keep on the fuel it continues to chug(miss? If I let off then slowly apply fuel it clears up.once it clears up I can step on it with no problem.when this happens it does not throw any codes.any ideas.
how di you go with that problem? Mine is doing the same, any suggestions? Thanks
Tsmiff1

Bentonville, AR

#16 Mar 10, 2013
happy go lucky wrote:
Have c12 runs great except when it gets warmer outside. Then it will chug(miss?) Only when warmed up and only if I shift quick.if I keep on the fuel it continues to chug(miss? If I let off then slowly apply fuel it clears up.once it clears up I can step on it with no problem.when this happens it does not throw any codes.any ideas.
If you found out what the problem was please share with us, my c12 is doing the exact same thing.
Gidfrey

Gaborone, Botswana

#17 Jun 24, 2013
Have a c12 will only start with quick start at times tif I keep it revved up it keeps running fine but let the Acc pedal it just dies any ideas, have swapped computer box, high pressure pump,primer pump n all fuel pipes same thing
road farmer

Livonia, MI

#19 Jun 5, 2014
happy go lucky wrote:
Have c12 runs great except when it gets warmer outside. Then it will chug(miss?) Only when warmed up and only if I shift quick.if I keep on the fuel it continues to chug(miss? If I let off then slowly apply fuel it clears up.once it clears up I can step on it with no problem.when this happens it does not throw any codes.any ideas.
Happy go lucky, I know this is long ago, but did you ever find an answer? We have a Sterling with the exact same problem. We can't nail it down. Great truck when it runs. Thanks.
road farmer

Canton, MI

#20 Jun 28, 2014
Found it!!!!!!
there was no engine light, but we took it to Cat. They found several codes (no light?). Anyway, it was the crank position sensor. I hope this helps somebody out.

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