BAC Forum
General Boards => Technical Support => Topic started by: Gene Obie on January 25, 2021, 06:54:02 AM
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After about an hr on the road the "Water in Fuel" light came on. Flashed a few times then stayed on. Luckily I found a weigh station to exit. Checked the manual and it said to not continue due to possible injector damage.
So following the manual I shut off the engine, and with ignition on and press the purge button on the Racor. But nothing seemed to happen. No light and no indication of any water coming out. Should the light come on when I depress purge regardless of whether water is detected or not? Perhaps I have a blow fuse or bad solenoid in the Racor?? So after this failed attempt to purge I restarted the engine and magically no "Water in Fuel" light any more. I drove another 2hrs to destination with no issues. I'm sure I need to replace the filter but I'm sort of an isolated spot here. Can I just remove the connection at the bottom of the filter to manually drain any water?
I filled the tank last time out at Loves so doesn't seem like I would have gotten bad fuel at big truck stop. Weather here is in the 30's so wonder if cold is contributing? Unfortunately, I didn't pay enough attention to the big note in the manual indicating one should always carry a spare filter. Live and learn.
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Gene, the lamp that you are talking about is telling you that your secondary fuel filter 1R-079
has reached its end of useful life and needs to be replaced. The lamp coming on and going off
Is a warning sign on your computer that filter needs to be replaced. If you continue to operate
engine after 13 psi back pressure resistance within the fuel filter your engine will derate to 37 %
of your engine power. Last this fail safe system is set up for use of caterpillar filter 1R-0749 only.
Installing aftermarket fuel filter in replacement of the caterpillar fuel filter will remove the fuel
System fail safe while using something other that Caterpillar fuel filters in the fuel system.
Dave Atherton Retired Cat Mechanic
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Last spring I had the fuel filters replaced at our local CAT dealer, at least I though he changed both the primary (Racor) and CAT (secondary) filters. Not long after we started out trip, the 'water in fuel' light came on, intermittently. I checked the sight glass at the bottom of the primary filter, no water. The mechanic had not replaced the primary filter. The light came on intermittently for the following week or two with no other symptoms. Same scenario happened on our first trip with the coach in 2015. No damage done, but next time I'll make sure they change both filters.
I don't know how the secondary fuel filter would be able to turn on the "water in fuel' light.
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Bill - there must be a back-pressure switch inline. Dave said over 13 pounds back pressure turns on the light.
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That's the thing, to measure pressure drop across a filter, you need two pressure sensors, one on either side of the filter. Then (I guess) the ECU makes the calculation and turns on the light. this circuit would have to be in parallel with the water in fuel circuit, the one in the filter bowl that looks for ground when there is water in the fuel. I don't know of any such series of pressure sensors, but I am not at all an expert on CAT engines!
The point of my post was to say the same thing (water in fuel light on) has happened to me, right after the secondary filter was changed (its happened twice now). One time we were in Colorado and I had some white smoke on start up, changed the secondary fuel filter and smoke went away. No water in fuel light that time.
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I order a new Recor S3230p equivalent primary filter from Napa (best I could get anywhere reasonably close to where I'm at.)
But now I see there's another "secondary" CAT filter" 1R0749. Any guidance on where that is located?
Thanks for info so far. I'm getting more concerned I shouldn't drive the rig at all until both of these are replaced. I'm at a state park 2-3hrs from any cat/diesel shop and really wet here so getting under this beast trying to find and replace fuel filter may be a bit of a challenge. Bummed at the last minute I decided not to load my safety blocking I use for getting under the rig.
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The Racor primary filter is the one you can see easily, the CAT secondary filter (I think) is behind it, it mounts to the engine block. I wouldn't be concerned about driving the rig if you can't find water in the Racor bowl. Like I said, the water in fuel light has come on during two separate occasions to no ill effect. You've checked for water in the bowl, I would just drive to your next destination and find a shop along the way to change the filters. BTW, I think the mechanics replace the smaller Racor filter with a larger filter from WIX, don't know if it makes a difference. I think they have a harder time getting the Racor so they just go with what is available.
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Re-reading Dave's post, I think what happens is that CAT monitors fuel pump pressure, if that exceeds 13 psi then the engine could derate. High fuel pump pressure (due to a clogged secondary filter, say) could lead to reduced fuel delivery to the injectors, not a good situation. I think the proper CAT filter is a 1 micron filter (correct me if I am wrong).
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Confused on the terms. It looks like the output of the primary (Racor water separator filter) goes directly to the fuel pump located on the back of the c13 block? And the "secondary" filter input is from the fuel tank? Is that correct? If so, seems reversed to call the first filter the "secondary".
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https://www.blog-teknisi.com/2018/12/fuel-system-c11-and-c13-caterpillar.html
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Thanks Bill, that helps.
Seems last owner put in 3rd party secondary filter - not a CAT. How much could they have saved with some after market filter - geez.
Based on what I'm reading here best to use only cat filter. I think I will pick up Napa filter FIL3674 for emergency use on ride out of here next week but replace secondary with CAT if I make it home ok.
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As long as its running ok now, I wouldn't worry about the light, just get 'em changed when you can. Gonna rain here like it does in Puget Sound starting tomorrow. Batten down the hatches!
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Gene,
Ask Dave, he will share how Caterpillar engineered it's CPU around that 1R-0751 2 micron secondary filter. That is how the computor measures the resistance in the system. I believe "Fleetgard" is a 15 micron filter thus nullifying the computor monitoring. The return fuel line on the pump on the back of the engine is the "input" into the secondary CAT filter (1R-0751)
You may want to inspect both hoses on the pump, mine was oozing diesel fuel. Hope this helps, Fred
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Gentlemen, how the caterpillar fail safe works within the fuel system and caterpillar fuel
filters are used. Caterpillar fuel filters are rated as a 2 micron new and installed on
engine sets up a 5 psi back pressure resistance with fuel flow through the fuel filter.
Remember the secondary fuel filter the 1R-0749 is under pressure from the fuel transfer
pump and the primary fuel/water filter is under suction to the fuel transfer pump. When
secondary fuel filter is nearing its usefulness at 10 psi lamp on dash will come on and go off.
When the fuel fines reach 12 psi lamp on dash will come on and stay on, than when 13 psi
back pressure is reached the engine will derate engine power to 37 % . Last replacement
With new caterpillar 1R-0749 fuel filter engine lamp will go out and engine power restored.
Dave Atherton Retired Cat Mechanic
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Thanks for the great explanation Dave. Along with the attached diagram from the link Bill sent I have much better understanding of basics of this system.
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Thanks Gene and Bill for providing the link and diagram. Further on there I checked the blog for the C9, but found an apparent slight information conflict.
At the top of the article a master diagram identifies item #11 as the Primary filter, but further down an HEUI low pressure fuel system diagram implies that same filter (#11) as the secondary filter and #24 as the primary. Unless I’m missing something, which as a diesel inexpert is quite possible, that second diagram’s legend is not correct and has the filters identified in reverse. The primary with it’s more porous material should be first after the tank.
https://www.blog-teknisi.com/2018/12/fuel-system-c7-and-c9-caterpillar.html
I hope our supplying these links is not afoul anyone’s copyright or policy; perhaps Steve can confirm.
https://www.blog-teknisi.com/2011/05/disclaimer.html
-Joel
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Joel,
Not sure where that diagram came from but it appears to be incorrect for the C9. In the C9s (at least the majority of them that I am aware of), the primary fuel filter is mounted below and part of the fuel pump. The fuel pump is not part of the injector hydraulic pump.
Steve
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So, Next time I get a water in fuel light, is it 'water in fuel' or 'secondary fuel filter' problem?
Would be nice to have a separate light for each condition.
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I was mistaken. The pump at the primary filter is a boost pump to increase the volume and pressure of fuel flow to the pump driven by the injector hydraulic pump. Some of us added the boost pump since the design of the C7/C9 calls for the fuel tank to be relatively close to the engine, not 30+ feet away.
My apologies, Joel. (Memory is the 2nd thing that goes with age :) )
Steve
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Yeah, that didn’t seem right... the main C9 pump being directly associated with the primary filter. My filter doesn’t appear to be that way, so I was scratching my head when you said that, but then I’m a relative novice on the subject. I do remember, however, discussions of Dave’s suggestion to add the boost pump.
My rig has never had the associated issue, and my shorter coach I think positions the tank closer to the pump system than others that may experience inadequate pressures. If I ever manage to get to Dave’s Arizona facility I figured on having him analyze our whole configuration, and implement his advice accordingly.
Joel
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"If it ain't broke, don't fix it"
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To follow up on this. I was able to get Napa "equivalent" primary and secondary fuel filter shipped to nearby Napa store. I replaced the primary with some difficulty. The filter was really stuck and strap wrench collapsed the filter no matter where I gripped it (was thinking I really got myself in a pinch laying there in the rain). Finally wrapped the filter in some thick double stick tape I had and that kept the strap wrench from slipping and finally allowed me to get it off. There was some water droplets in drained fuel so I'm thinking my "water in fuel light" was actually from the primary filter detector. My coach manual also indicates that light is driven by primary water detector. Maybe the secondary pressure drop also drives that light or perhaps the "Engine Warning Light". The owners manual is not clear on what trips the warning lght.
The racor priming procedure worked as advertised and the CAT started without a hiccup and ran great on the trip home. I'm keeping the Napa secondary filter as a spare and will put in the recommended CAT filter before next trip. It looks like a bear to get to sitting there between rail and engine.
Put a check next to another item on my list of how to keep this thing rolling down the road.
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My 25’ Searay sport cruiser’s oil filter hit me with that issue on a road trip north to the San Juan Islands 45 years back. Fortunately I’d stopped to do the maintenance and overnight at my sister’s in Bellevue on the way. My brother-in-law was the regional service rep for Oldsmobile division of GM, and handed me an oversized screwdriver (16”?) to literally punch through the middle of the filter. That offered essentially two handles to apply torque to, and the filter came off. But, oh by the way, it’s a bit messy.
I’ve since found many experienced techs that have occasion to use this not too uncommon technique. Be sure you’ve applied some fuel to the new seal before screwing a replacement filter on, and tighten per engine/filter recommendations.
Joel