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CAT C4.4 acert won’t start until it gets some sniff

Andrewk143

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Oct 11, 2022
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United kingdom
Our cat c4.4 won’t start until we give it some sniff and then it starts no problem and runs no problem, any help would be appreciated
 

Nige

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Jun 22, 2011
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G..G..G..Granville.........!! Fetch your cloth.
Serial Number.?
How many hours on it and what's it installed in.? Got any photos of the installation.? (You'll need to make at least 3 posts before you can upload photos)
First & most important question - Is the air filter maintenance up to scratch.?

If it's anything like the C4.4s we had in compactors it probably needs (in order of price) a rail pressure relief valve, injectors, or a high-pressure fuel pump. If the cheapest doesn't solve the problem then you move to the next expensive, etc, etc.

TBH the best way of diagnosing, if you don't want to simply shotgun a load of expensive parts at it, is to get Cat ET hooked up to it and start looking at the pressure in the fuel rail.
 

Andrewk143

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Oct 11, 2022
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Serial number 44423353 and it’s installed in a mcluskey s190 screen with 7596 hours and has recently been serviced but it has always been hard to start for over a year now
 

Nige

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G..G..G..Granville.........!! Fetch your cloth.
Does it smoke at all, either during starting or when it’s pulling a heavy load.?

The problem with engines in screens is that they tend to operate most of the time buried in spillage, and if the air filters are not serviced regularly the engine will get dusted PDQ. TBH with 8k hours on it in that type of application it’s probably close to being worn out, but hooking ET up to it would at least enable the fuel system troubleshooting to be done.

Post some photos showing the installation and the general condition of the engine.
 

John C.

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I don't know about this engine but lots of small Cat motors are rebranded units from other manufacturers. The hard starting issues I saw a lot of involved the automatic sensing for the pre-heaters. Many of those small engines won't start without the pre-heat and the control modules won't turn on unless ambient temperature is below a certain point. Lots of clients started using ether to get them started on 50 degree F. days and they then started the climb into needing more of the cocaine as time went on. I've had a couple of clients put in a manual button to work the pre-heaters which solved the issue.
 
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Nige

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Jun 22, 2011
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G..G..G..Granville.........!! Fetch your cloth.
I don't know about this engine but lots of small Cat motors are rebranded units from other manufacturers. The hard starting issues I saw a lot of involved the automatic sensing for the pre-heaters.
No grid intake heater on this engine John, but it does have glow plugs...........
The weird thing is that apparently the glow plugs are controlled by a relay but the full electrical schematic doesn't show it, only the abridged schematic in the Troubleshooting Manual.

upload_2022-10-14_17-35-53.png

upload_2022-10-14_17-45-34.png
 
Last edited:

nowing75

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Aug 5, 2009
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898
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coatesville indiana
Have had a few issues with the 6.6 that i believe is very the same. Check injector leak off. Had one that ran great once started. It fairly simple to do, if you need procedure i can get it for you when i get a chance.
 

illy

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Jul 10, 2010
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Down on Earth
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Service technician
Try looking at this also from this angle; at the crank speed (200 - 250 RPM) the engine is not self-sufficient. On idle it is.
So it could be as simple as not being able to draw fuel from the tank...
 

Andrewk143

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Joined
Oct 11, 2022
Messages
47
Location
United kingdom
Plenty fuel getting there, it seems to be starting a lot better at the moment who knows what has changed, will monitor and see what happens thanks again for all your help
 
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