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Cat Man
Cat Man, Caterpillar Engine Expert
Category: Heavy Equipment
Satisfied Customers: 8492
Experience:  23 Years Caterpillar Engine experience.
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Hay Cat Man I have a 3126 gh fuel pressure replaced fuel

Customer Question

Hay Cat Man I have a 3126 High fuel pressure replaced fuel regulator on back of the head had the head done at machine shop put it back together and the cab alarm is going off and the Fuel filter seal is popping out and fuel spraying every where
Submitted: 1 year ago.
Category: Heavy Equipment
Expert:  Cat Man replied 1 year ago.

Thanks for asking your question and requesting me. I will try and help you out.

Is it blowing the seal on the secondary fuel filter? If so, you most likely have a stuck relief valve in the fuel transfer pump. I have seen this many times. The valve in the pump is suppose to open at higher RPMs. When it does not, it will cause excessive fuel pressure. I would have the fuel transfer pump on the back of the heui pump replaced. I'm sure it will solve your problem.

Please reply back if you need more help or have more questions. I am happy to assist.

Customer: replied 1 year ago.
I put the transfer pump on and it still seems like there is high fuel pressure i will put fuel pressure gage on it in the Morning it 8:30 Pm In Wasilla Alaska
Dan
Expert:  Cat Man replied 1 year ago.

Thanks for the information. The fuel pressure should remain between 65-85 psi at all times. Let me know how you make out.

Customer: replied 1 year ago.
Hay cat man the oil pressure is very high the fuel pressure is very high after putting on the fuel transfer pump @ $273 with o ring the fuel pressure is still high and way would the oil pressure be high the oil gage max out
Expert:  Cat Man replied 1 year ago.

What psi is the fuel pressure?

Customer: replied 1 year ago.
200
Customer: replied 1 year ago.
but goes down when not sitting idleing
Customer: replied 1 year ago.
i drive it and 1800 rpm run smooth
Expert:  Cat Man replied 1 year ago.

I have never seen 200 psi. Where are you checking the pressure?

Customer: replied 1 year ago.
peggys out the oil gage
may be 165
Expert:  Cat Man replied 1 year ago.

The pump does not have the capability to produce 200 psi. If the manual gauge shows 200 psi, I would suspect compression from a cylinder is getting past an injector. It's rare but I've seen it a time or two.

If your oil pressure is that high it should blow off the oil filter. I would suspect your oil pressure gauge is not reading correctly.

Where are you measuring the fuel pressure?

Customer: replied 1 year ago.
hay cat man 123 psi in the gally ofthe head
Customer: replied 1 year ago.
im dieing here need truck on road
Expert:  Cat Man replied 1 year ago.

Thanks for the information.

If it's that high it must be coming from compression past an injector. It's the only way. I would remove and resell the injectors.

Customer: replied 1 year ago.
hay cat man fuel perssure is over 100 gage peg out high
Customer: replied 1 year ago.
oil pressure gage broke
Customer: replied 1 year ago.
fuel knock in engine
why do i have high pressure
Customer: replied 1 year ago.
run wih knock new head
just replace have not been be able to work
Customer: replied 1 year ago.
fuel pressure over 100 psi gage peg out
Customer: replied 1 year ago.
sounds right cant thnk that the pump valves
stuck open ??????????????????
Customer: replied 1 year ago.
HUEI PUMP
Customer: replied 1 year ago.
acccuration sensor high pressure valeve is stuck open may be ????????????????????
Expert:  Cat Man replied 1 year ago.

Thanks for the information.

If the fuel pressure is that high it must be compression getting past an injector. The heui pump can not cause high fuel pressure.

Customer: replied 1 year ago.
well I went through the fuel system looking for any kind of restriction the fuel lines all good , I took off the return line to tank after the furl regulator at the back of the head the furl regulator did not pop off the fuel filter poped again so I think the regulator is not working the part # *****(###) ###-####that # ***** from a M 7 NC said taht this is a generic one the right 1 is like(###) ###-####I think
Expert:  Cat Man replied 1 year ago.

Thanks for the update. If you can get me the engine serial number I can verify the part number of the regulator.

Customer: replied 1 year ago.
CKM47130
Expert:  Cat Man replied 1 year ago.

The part number I show is a(###) ###-####

Customer: replied 1 year ago.
why would the M7 fuel regulator not work same displacement same motor right
Expert:  Cat Man replied 1 year ago.

Yes same displacement. To be honest all the regulators should be the same. All 3126 engines have the same fuel pressure spec.

Customer: replied 1 year ago.
why wont the fuel regulator pop of
Expert:  Cat Man replied 1 year ago.

It should pop off at 75 psi. Not sure why it will not.

Customer: replied 1 year ago.
this is the 2nd 1 I put on it the real one is here at NOON ill
Expert:  Cat Man replied 1 year ago.

I see. Thanks for the information. Let me know how you make out.

Customer: replied 1 year ago.
defective is the fuel remember this is the vehicle that my driver put in 3rd gear at 65 the booster pump on the brakes popped out and no brakes so it bent 12 push rods so i had the head done all valves and seats and every thing elese
Expert:  Cat Man replied 1 year ago.

I see. Yes I remember. But I'm not sure what you are asking now. Your changing the regulator again right?

Customer: replied 1 year ago.
not asking just letting you know what happened to put me in this predicament LOL all good yes replacing the fuel regulator to the right part #
Expert:  Cat Man replied 1 year ago.

Ok sounds good. Let me know how you make out.

Customer: replied 1 year ago.
still having problems with thus 3126 went it start it put out a lot of white smoke like geting to much fuel
Expert:  Cat Man replied 1 year ago.

Did the fuel pressure go down?

Customer: replied 1 year ago.
I believe so the regulator I checked it and it was working correctly it poped of anf fuel was
Customer: replied 1 year ago.
flowing
Expert:  Cat Man replied 1 year ago.

Thanks for the information. If there is white smoke you are either sucking air or have a faulty injector.

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