I have a 2002 Cat 3126 installed in a Winnebago Journey on a Freightliner Chassis. For the last several months I have been having an intermittent starting issue. On most occasions the engine will fire right up on the first start attempt. On some occasions it may take 3 or 4 attempts. Outside temperature, warm or cold engine, time sitting idle (shutdown) doesn't seem to have any pattern. I've recently replaced the fuel filter with no change. Seems fuel related like it may be losing prime but it has happened after only being shut down for a few minutes. There is definitely no pattern. Any suggestions team?
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There is a fuel pressure regulator in the return fuel line at the rear of the cylinder head , it should maintain 65 psi in the cylinder head fuel passage , if it doesn't you end up with repeated start attempts and long crank times .
Yellow oval ; red oval is a heater hose.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
I received the new regulator, and removed the old one. There is a small pin that was just sitting in the regulator outlet when removed from the cylinder head (see pics). The new one does not have this pin. I installed the new one without the pin and started the engine several times with no issue. Any idea where this pin could be from or if necessary?
Any idea where this pin could be from or if necessary?
I've never had to change a fuel pressure regulator , but if your starting issue appears to be fixed , I'd guess it's unnecessary , particularly if the new regulator didn't come with one .
I can't think of anywhere in the fuel system that a piece that shape would come from .
I do have a repair manual for a 3126E , I'll look through for any clues to it's origin .
EDIT: BTW , the regulator is in the fuel return line from the head to the fuel tank , so the pin is in the regulator inlet .
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Thanks for the reply and explanation on the direction of flow. Seems to me that the pin setting in the inlet of the regulator could have intermittently prevented the poppet inside the regulator from closing off and allowing the fuel pressure to leak down to the tank causing my starting issue?? I'll keep my fingers crossed and let you know if I have any more starting issues. Thanks again!
Not sure if it's related or not but I have done a few trips since I replaced the regulator and I now have an issue with top end speed. Starting is perfect and take off and acceleration seems normal. I can no longer exceed about 60 mph unless going down a hill. Also, while climbing the I-10 bridge in Lake Charles, LA on the last trip it slowed down to about 35 mph. Used to be able to maintain 55 mph with no problem. Again, starting and acceleration at low speed seems normal. Any possibility that the "mystery" pin that appeared in my fuel pressure regulator inlet came from an injector or something that would limit top end performance? Also note, if I downshift to 5th gear, the RPM climbs to over 2000 but the coach will not go any faster. Puzzled...
The symptoms you described are classic for a restricted fuel filter(s).
Jeff
Also , there is a possibility of a fuel strainer in the fuel line above the right rears suspension air bag.
As per diagram and photo.
The strainer on my chassis had been removed by a previous owner.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Thanks all! I have searched for the frame mounted strainer and did not find one. My coach does not have an engine mounted filter. I will be replacing the filter/ water separator next week and will update this post. Merry Christmas!!
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