2002 Beaver ecm hard wired how to test or replace or to check fuel flow.

[Wilbur Doolittle]

Cat 3126 quit running setting at stop sign.  Had to tow it home replaced fuses in ecm none blown, cranks but will not run if you give it small shot either it will not very long new owner need to know fuel pump location and if there is more than one pump. First Occurence 3000 miles last fall put away for winter pulled out seemed ok filters were replace last fall b4 trip. Looking for ideas where to look. ECM appears to be hard wired in.
 

[Eric Maclean]

Wilbert
The 3126 is a HEUI ( hydraulic electronic unit injector ) engine it has no mechanical injector pump but instead has a gear pump driven off the back of the high pressure hydraulic oil pump both of these pumps feed internal galleries in the cylinder head one with diesel fuel and the other with high pressure engine oil .
Each injector is connected to these two galleries and when commanded by the ECM via a high voltage signal uses the high pressure oil to compress the fuel in the injector during an injection event the start point and duration of the event are controlled by the ECM.
The high pressure oil is monitored  by the ECM by means of a pressure sensor in the high pressure oil gallery
And controlled by the ECM via a solenoid mounted to the high pressure pump.

With all of that said the gear pump draws fuel from the fuel tank through the fuel separator and then pressurizes the fuel sending it through the secondary fuel filter and on to the cylinder head fuel gallery the fuel pressure is maintained in the gallery by a spring loaded fuel pressure regulator at the back of the head ( towards the front of the coach under the bed).
The majority of problems arize from air being sucked into the system on the suction side of the system most commonly at the fuel separator Beaver used a Coleman/Racor fuel separator and priming pump these have a plastic sight glass which is sealed with 4 O rings and are very prone to allowing air to be sucked into the fuel system.
The resulting air creates problems with low power,hard starting and injector failures due to poor lubrication.

If you have a no start situation
1) start by bleeding the fuel system using the priming pump ( run the pump and depress the Schrader valve on the fuel separator until clear fuel is seen at the Schrader valve the loosen the fuel filter until the fuel runs out at the filter base the tighten the filter back up and continue to run the priming pump for another sixty seconds to push fuel through the gallery and out through the fuel pressure regulator at the rear of the head.

If this resolved the no start
you are likely loosing prime via the fuel separator as described above to verify whether or not you are getting air into the fuel system remove the fuel line from the fuel pressure regulator at the rear of the head and connect a clear hose between the fuel pressure regulator and the return line make a loop in the clear hose to create a trap of sorts then run the engine at a fast idle after two or three minutes monitor the clear line for bubbles coming out of the fuel regulator . There should be no signs of air bubbles
If you do get bubbles then start at the fuel separator remove the site glass and replace the O rings there are two o rings at each end of the sight glass one in the housing and one on the sight glass tube.
The O rings can be picked up at any good hydraulic shop they are made of nitrile and are #114 and #208.

Hope this helps
Eric

[Wilbur Doolittle]

Thanks in advance will check this out, but how does one verify the Ecm is working?
What is an alternative to the raycor?

Where is priming pump and how to activate it?

[Eric Maclean]

Wilber
The Racor can be replaced with a Cat fuel filter assembly with a pump there is a description in the coach assist section.

With the a no start situation there are several things that will prevent the engine from starting
1) no fuel or not enough fuel pressure to the fuel gallery it needs in the neighborhood of 60 psi.
2) no high pressure oil at the high pressure gallery in the head it needs in excess of 750 psi just to start
3) it needs power to the ECM at both the ignition feed and the battery feed.
4) it needs a good signal from the timing sensors ( crank and cam )

The best way to determine whether your no start is ECM related or one of these other things is at fault is to connect
A San tool to the system. (preferably a scan tool with CAT ET. ( electronic technician software) this will allow you to communicate with the ECM an see the input voltages and the injection actuation pressure as well as many other parameters.
However most of us do not have access to a scan tool.

If you have an Aladin system of any system on the dash which reads engine parameters directly  from the Cat ECM and it is showing you any information such as engine coolant temp or intake temp . The ECM has to communicate with that system to show those if you have that information present the ECM is powered up and communicating.

If no communication check in the battery bay for two inline fuse holders attached to the battery cable bundle near the chassis battery these are the battery feed fuses for the CAT ECM and the Alison transmission TCM.( These wires and fude holders can get rotten from the battery acid and create problems)

If still no communication first check the ignition feed circuit breaker marked ECM on the right hand buss bar in the electrical bay under the drivers platform for power with the key on ( the ignition solenoid has a bad habit of failing )

The ignition feed is sent to the ECM by an ignition relay located at the left rear upper corner of the battery bay and it is controlled by the switch in the service bay  ( front and rear control switch ) these are in a bad spot for dirt and corrosion and these switches can create starting problems over time)

The wiring diagrams are located in the coach assist section of the forum to help you diagnose .

For a quick check you can use an inductive household circuit tester ( the ones you just touch up against a wire that will light up if there is voltage present)
As mentioned before the injectors are controlled by the ECM with a high voltage pulse and by placing an inductive test against the wires feeding into the rear of the head and having someone crank the engine you should be able to detect the injector pulse provided by the ECM it will be a short flash there are six sets of wires in the bundle going into the back of the head it's best to stick the nose of your tester right into the center of the bundle and keep the bundle tight around the tester to see the results
If you have activity ( flashing light means ECM is working and controlling the injectors )

I hope some of this is helpful
Eric

[Wilbur Doolittle]

After doing some investigating I am trying to repair the fuse chassis panel in the battery box Previus owner ran wires wher they do not belong and fuse connectors came off the panel.

--->Fuse Chassis Panel needed.<---

Need a replacement if anyone knows of one but still trying to fix this one HELP PLEASE thank in advance

[Eric Maclean]

Wilbur
I'm not sure who the manufacturer of that panel was but a picture might help identify it
 
Your best bet might be to contact one of the RV wreckers like Visone or Colaws for a good used panel
Visone is in Kentucky and Colaws is in Missouri.

https://usedrvparts.visonerv.com/

https://colawrvsalvage.com/product/

Hope this helps
Eric

[Steve Huber Co-Admin]

Wilber,
Coach Assist doesn't have the 2002 Monterey wiring diagrams but if you check pages 40, 41, and 43 of the 2002-2003 Patriot wiring diagrams you'll find both the mechanical and wiring diagrams for the rear panel. They  should be very close, if not identical to your Monterey panel.
Steve

[Wilbur Doolittle]

Steve thanks I did look at the 02 03 Patriot but did not find the pages you were referring to I did see the ones on the Cummins. Thanks again still looking.

[Steve Huber Co-Admin]

The sheets are labeled "Isolator Board". You have to log into the BAC website, select Technical, then Coach Assist. Page down to the Wiring Diagram section which is near the end. Then look under Patriot Wiring Diagrams. If you can't find it let me know.
Steve

[Wilbur Doolittle]

Finally have picture of actual block I am working on

[Steve Huber Co-Admin]

Wilbur,
Just curious, do you know how to correctly wire the panel? If not, was the panel wired when you removed it? If so did any of the wires have labels / numbers on the insulation? From the photo it looks like the panel may be repairable if you can't locate a replacement. Also was something mounted with the 2 (what look like clips) midway  on the vertical sides? Hopefully another 02 Monterey owner can supply more info.
Steve

[Wilbur Doolittle]

Thanks Steve all was labeled and I relabled before getting it out will add about 20 inches of wire and place it to the front access of the battery box I ordered a new relay plus wire harness and have to fuse links to solder back into place. That should make it almost like new with a few upgrades the connections on the crimps were the worst I have ever seen in my 30+ years in electrical and mechanics.
It would have failed eventually so I am glad I was not far from home

Thanks again to all who contributed to my aid I appreciate it greatly

Wilbur Doolittle

[Steve Huber Co-Admin]

I agree re crimps. I had lots of issues with my 2000 and 2001 with bad crimps. it was a real pain tracking them down. Worst were in the bedroom slide circuit in the 01.
Glad you've got it under control.
Steve