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 Cat 3126 Cranks but won't start
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Posted - 11/15/2012 :  1:57:33 PM  Show Profile  Visit Stan's Homepage  Reply with Quote
I have a 3126 in a 2004 Ford that was running fine when I parked it. Tried to start it after is sat for a couple of weeks. The engine cranks like it should but makes no signs of starting. The engine has only 49000 miles on it.

After reading several posts on here I checked engine oil. It was really low. The engine has never used any oil before and has about 5000 miles since last oil change. I filled to full (about 2.5 gal) still no start. Fuel tank is nearly full. Both filters have fuel in them. This model does not have a hand primer so I rigged up an electric fuel pump with valve and gage to the #6 plug on the secondary fuel filter (on the cyl head side). Bled the air and pushed 20 psi fuel to it and still no start. Also tried just a little either and it will run on it but I didn't get too carried away with that.

I have good fuses down by the batteries. The wire labeled ECU gives a nice little spark when I pushed the fuse back in so I expect the ecu is powered. The intake heater relay energizes when it is supposed to and I can feel the intake get a little warm to the touch after a couple of cycles so I believe it is probably ok.

The cruise/rpm switch method revealed 2 codes. #39 and #38.

I don't have access to a code reader. I do have a have a Fluke 2 channel O-scope and might be able to get a pattern on the cam sensors.

I am about to start trying to look at IPR parts but am not really sure where they are. The diagrams I have seen don't look exactly like my configuration.

No warranty! Any thoughts?


Edited by - Stan on 11/16/2012 06:57:49 AM

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Posted - 11/16/2012 :  05:48:03 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
39 is a failure of the injection actuation pressure system, with the loss of oil and no mention of leaking oil visible outside the engine it may be safe to assume the possibility of oil leaking past the ijector o rings that control high pressure oil into the fuel system next set of o rings down from the oil set. the injection oil pressure needs to be over 650# to start the unit and may reach 4000# while operating. if you attempt to start unit with eathe you MUST first unhook the plug to the grid heater relay. you may be able to pull the fuel return line and check for oil out of the fuel rail in the head. 38 is an intake temp sensor circut fault voltage low or high.
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Posted - 11/16/2012 :  7:38:19 PM  Show Profile  Visit Stan's Homepage  Reply with Quote
I learned a little more today. Still haven't had a scanner on it but the cat dealer thinks the heui pump and all 6 injectors need replacing ($3600.00 parts only). He says the low oil has killed the pump and spread metal cuttings throughout the injectors. He gave me a couple of things to try, one of which was to pull the cover off the heui pump and check for metal cuttings stuck to the magnetic coil inside. By the way my engine in Serial# HEP 280486.

I tapped into the high pressure oil galley and put a 4000 psi gage in. Had a helper crank the engine while I watched. The pressure started up kind of slow and then quickly headed toward max on the gage. Next I unplugged the connector in the top of the heui pump and tried again. This time the pressure went to about 700 and stayed. I was sure I had eleminated the pump as the problem. The CAT dealer was not so optimistic. Just before 5:00 he gave me one more thing to try....unplug the high pressure oil pressure sensor and see if it would start. The engine starts! It cranked longer than normal, but ran smooth and revs up like normal. The pressure is 800 psi at all rpms. Remember the pressure sensor is still unhooked. We hooked it back start. Just like it was before. The dealer was closed so I am unable to report my findings.

I think I am going to try a new sensor unless someone on here talks me out of it. What worries me is that the engine cranked considerably longer than normal before starting while we had the sensor unplugged. I have no doubt that the ecu is confused without the sensor input.

The next thing is the sudden oil consumption. Nothing here explains that.

Any suggestions?

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