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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8628
Experience:  I am ASE Master Truck Certified.
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I have put 2 reman heup pumps and have 6 psi on the fuel

Customer Question

I have put 2 reman heup pumps and have 6 psi on the fuel pressure and little or no oil pressure. We put a rebuilt engine with rebuilt injectors from the cat dealer back in march it has about 5000 miles on it . We pulled the valve cover off and checked
the injectors and all the bolts were tight with no oil leaks visible. Parts that have replaced- fuel pressure control regulator, engine speed sensors, ecm. Also I made sure the gears were turning on the motor. The pump is mechanical? could it be I have 2 bad
heui pumps? Thanks Tommy
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 1 year ago.

Hey Tommy. Thanks for asking your question. I will try and help you out.

Can you get me the engine serial number please?

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

Thanks for the information. Sorry for the delay.

Yes it's possible to have two bad pumps. But that is rare. So is the engine a crank no start? Do you know if there are any codes in the ECM?

Customer: replied 1 year ago.
We hooked up yesterday its not connecting to the ecm the connector on the truck has been tampered with but has been that way since we've had it. I don't understand what you mean by "crank no start" you can put starting fluid in it and it will start for a second.
Expert:  Cat Man replied 1 year ago.

Thanks for the information.

By crank no start I just mean the starter turns the engine over good. But the engine just does not run on its own. Is that what it's doing?

Customer: replied 1 year ago.
it is turning normal.
Expert:  Cat Man replied 1 year ago.

Thanks for the information.

Does the yellow check engine light come on when you turn the key to the on position?

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

Thanks for the information.

Since the yellow check engine light comes on, this indicates the engine ECM is receiving power and functioning. There are several things that can cause a crank no start on this engine.

The first is a low or no fuel pressure condition. The engine needs at least 20 psi to start. If it is low, the injectors will not get filled and it will not start. If the engine has a hand priming pump, and it gets stiff when operating it, the engine has enough pressure to start. If there is no hand priming pump, I would connect a psi gauge and measure the pressure. If the pressure is low, I would change the fuel filters first if you haven’t already. If it is still low, I would suspect a failed fuel pressure regulator on the back of the head or a weak fuel transfer pump. The pump is located on the back of the HEUI pump.

Second is a low injection actuation pressure. This is the high pressure oil system that activates the injectors. The engine needs at least 870 psi to start. If it is low, you have either a failed Injection actuation pressure control valve in the HEUI pump, a weak HEUI pump, a high pressure oil leak at an injector, or a faulty Injection actuation pressure sensor. To test the sensor, just unplug it. If the engine starts, the sensor is bad. It has 3 wires and is located on top of the engine near the front and screwed into the head.

Third is a failed engine speed timing sensor. Your engine has two. They are located on the driver’s side of the engine on the back of the engines front cover under the HEUI pump. The bottom sensor is the primary start sensor. If it has failed, the engine will be hard to start. The top one is the primary run sensor. They come as a pair.

Next is low battery voltage to the ECM while cranking. The ECM must have at least 7.5 volts DC to operate. I have seen weak batteries or a poor connection cause low voltage. You could have a poor connection at the batteries or starter.

Next is a faulty engine ECM. The ECM has an injector driver module inside. This is what powers the injectors. If it fails, the ECM will log injector codes for all the injectors.

Lastly are worn injectors. Over time the injectors can wear if they have a lot of hours on them. To verify, I like to check AC to the injectors while cranking. You should have between 20-40 AC while cranking. If you do, and you have good fuel pressure, the injectors are worn.

Most often when these things are happening there will be diagnostic codes in the ECM. If your engine has cruise control switches, you can pull the codes. If you have never done this, let me know. I can get you the procedure.

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

Customer: replied 1 year ago.
it has 6 psi fuel pressure and no oil pressure I cracked the line on the back on the heui . I've checked all of the other parks or replaced them. Is the adjustment on the heui?
Expert:  Cat Man replied 1 year ago.

Thanks for the information.

No there's no adjustment for the heui pump.

If you are not getting any oil to the heui pump. You may have a faulty engine oil pump or problem with the pickup tube on the oil pump.

Expert:  Cat Man replied 1 year ago.

Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.

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