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Dead on the road
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=93149		 Page 1 of 1
Author:  adklettke [ Wed Mar 25, 2026 11:44 am ]
Post subject:  Dead on the road
Three weeks ago, I was driving south out of Tucson at 70mph, when suddenly the jeep started shaking like an old hound dog. I thought I had a blown-out tire and pulled over where upon the engine was dead. I tried to crank it and nothing.
Towed back to a friend's business and tried to diagnose the issue.
Pulled back the timing belt cover and it was tight and in good condition. It moved when the engine cranked.
I had bought a new fuel filter and used this opportunity to install and bleed the system, no change.
Pulled the hose off the regulator at the end of the rail and no fuel came out. But I did manage to break the little nipple for the injector return line to that plastic return manifold.
Pulled the plug from the CP3 pump and no change.
Checked fuses along the way and all were good.
There is no tank boost pump but the hand pump would pump up hard.
I sprayed starting fluid into the intake and the engine fired up, so it's a 100% fuel issue.
I needed to return to my boat in Mexico and had a ride back and so had the jeep towed to a diesel mechanic my friend recommended. It has been three weeks now and I order a new regulator solenoid from ID Parts and it was delivered. I guess he cooked my started as my friend needed to buy a new one. The mech said he will get back to working on it today.

I was also suspicious of a large volume of fuel being returned by the CP3 pump. I have left it up to the mechanic as my experience with diesels is with boat Yanmars etc.
The jeep has been running perfectly without power loss until that moment. I did lose part of the serpentine belt on the trip north and had installed a new one the morning of the fuel failure. I thought it might have taken out a wire or sensor but couldn't see anything. The only engine code was 0087.

I appreciate any diagnosis guesses etc. Has anyone here had a similar situation?
Author:  WWDiesel [ Wed Mar 25, 2026 2:00 pm ]
Post subject:  Re: Dead on the road
P0087 -- Fuel rail/system pressure – too low Fuel pump, fuel pressure regulator, fuel supply pipe blockage, mechanical fault
Since you lost a belt earlier, make sure the IAP Sensor did not get damaged or become unplugged. It will make an engine run very poorly.
IAP sensor – OEM part no.: 05101120AB (intake air pressure sensor on side of airbox)
air inlet air pressure comparator pressure sensor on the side of the air box;
sometimes referred to as the “Mercedes sensor”
• Bosch part no.: 0261230189.
• Mercedes OEM part no.: A0051535028
• AutoZone part no.: 0261230189

    POSSIBLE AREAS TO CHECK:
    1.**Air in fuel - leak on suction supply to CP3, stopped up fuel filter, etc... Inadequate fuel supply to CP3 will prevent injection pump from supplying proper fuel pressure to fuel rail)
    IF the CP3 is returning too much fuel.
    2. Cascade/Overflow Valve (on top of CP3) Regulates lubrication to internal parts of the injection pump and regulates the fuel pressure to the fuel quantity solenoid valve on the back of CP3 injection pump. Also, controls the amount of fuel being returned back to the fuel tank via the fuel return line.
    3. Fuel Quantity Solenoid (on back of CP3) [Also referred to as the Fuel Control Actuator or FCA ] The Fuel Control Actuator solenoid valve is a pulse-width modulated valve that controls the amount of fuel sent or delayed to the high-pressure pump elements inside the high-pressure pump. If all of the above tests pass and rail pressure is still below spec, try unplugging the Fuel Control Actuator Valve (FCA) on the CP pump and see if the rail pressure increases, if not, the CP3 injection pump could be bad internally.
**No. 1 cause of No Start Condition!

Quote:
Both the FCA and the Cascade Overflow valve are replaceable and available online for purchase.
FCA: Mopar: 5159962AA Bosch: 0928400822
Cascade Overflow valve: Bosch: F00N200798


As to the fuel return plastic block, you can make one out of simple brass fitting from any hardware store, see second drawing below.

Image

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Author:  adklettke [ Thu Mar 26, 2026 7:37 pm ]
Post subject:  Re: Dead on the road
You are a wealth of information, thank you for sharing.
Author:  adklettke [ Fri Mar 27, 2026 1:18 pm ]
Post subject:  Re: Dead on the road
The mechanic in Tucson just told me that the only the CP3 pump is returning too much fuel. He suspects the Cascade Overflow Valve which he can source locally. He did say that unfortunately he can't access the valve because it is behind the bracket that mounts the pump and alternator and is a huge job to remove.
I have suggested that if he can get access is to cut or drill access through the bracket so he can remove the valve. Has anyone ever done this before? I'm not too concerned about the bracket as the alternative is major engine work for a $30 valve.
Author:  WWDiesel [ Fri Mar 27, 2026 10:56 pm ]
Post subject:  Re: Dead on the road
The CP3 bolts to the front of its bracket and that bracket bolt to the side of the engine block. The alternator and its bracket is easy to remove to gain access to the top of the CP3 pump. It is a seperate bracket from the one the CP3 injection pump bolts to.

Image
Author:  rankom [ Sun Mar 29, 2026 8:14 am ]
Post subject:  Re: Dead on the road
Did your mechanic tested injectors? one maybe stuck open..
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