Coming up the mountain on I64 West of Charlottesville VA today, I lost a significant amount of power. Coach downshifted as I began to lose speed, but it acted as if it couldn't get enough fuel under load. Put the blinkers on and camped out behind a slow semi truck doing about 35mph for 6 miles up hill.
Water temp climbed 5 degrees or so to 185F (normally runs right at 180F). None of the other gauges indicated an issue. The campground was only a few miles off the interstate so I limped to my destination. RPM response seemed sluggish and there seems to be a point on the throttle/load that the engine starts to feel as though it hits a governor (though RPMs are about 1600, so not really a governor kicking in).
Am I right in thinking this is probably fuel filters that needs replacement? I have a new primary and secondary on board, but haven't done this job before.
Any tips? I found a basic walkthrough from Pierce in this thread: Oil amd Fuel Filters DD6V92 (https://www.foreforums.com/index.php?topic=32733.msg294227#msg294227)
Thanks all!
Chip
Absolutely with all other indicators being good and significant power loss, start by replacing both fuel filters.
You might open the primary up (hack saw) to see if there is crud in it.
Also, make sure there is no black algae in the see through plastic end on the primary filter. Use plastic bags to save your self a mess. You have the frame mounted manual fuel pump down on the right looking in the engine compartment. Leave the new filter a turn loose and pump fuel until all the bubbles are gone. Tighten as indicated on the side of the filter. Do you have all the new filters?
Clogged fuel filters while having your symptoms, usually have a smooth idle.
Always carry two spares for each filter just in case you get a big load of contaminated fuel.
I put two pressure gauges on the pressure out of the hand pump and another gauge on the outlet of the secondary. Easy and cheap to do.
PM if you have trouble.
Pierce
Thanks Brett and Pierce!
I've done some additional reading on the forum and can't seem to reconcile what I'm seeing as the primary filter/separator with what I'm reading. Specifically the clear part of the filter or housing and the manual pump.
It is dark, so I'm probably missing something in the low light. I've attached a pic of the primary and secondary fuel filters on my coach. Will look further for the pump tomorrow in the daylight.
I have one new primary and secondary of the same part numbers on board. Will procure a couple of additional sets to have in the future.
Thanks!
Post the PN's:
Primary:
Secondary:
Primary: P558010
Secondary: P556916
The correct Donaldson fuel water separator for our is P/N P553202, it has a "twist and drain" attachment on the bottom.
It has no "bowl assembly".
The filter called for in the manuals, ours anyway, is a Racor/Parker S3202 with clear bowl assembly on the bottom.
Replacement Parker part number for the bowl is RK 3005.
Chip your P550810 has the same twist and drain bottom.
Probably work fine
The primer pump is that black knob to the right of the filter in the picture.
I will use the Donaldsons I have for the moment, but there seems to be an advantage to having the clear water separator bowl with the Parker. Looks as if I just order the bowl and filter and would be done with it. Now I understand why some advocate a second bowl for filter changes!
Fill the new filters with fuel before installing. It will save your arm from so many pump strokes.
Thanks everyone!
Replaced both fuel filters with no problem. Really glad for the tip to pre fill with diesel fuel before screwing them back in (through the pre-filter holes). After playing with the manual pump, I think it would have taken forever to charge them without the prefill. Not sure I was using the pump correctly though.
I was able to source a couple of spare secondary filters from a nearby Napa (in stock). They had the primary in stock that would have used the factory racor bowl, but I don't have that currently.
Should I source a racor bowl and use that going forward, or go with something else?
As an aside, I decided to test the air filter restriction meter as well. It worked great, and did not indicate a filter change was needed. I pulled the filter out anyway to check the date and it was October 06! Sheesh. Replaced from Napa with a new one.
These two changes definitely have the motor sounding smoother. I'll have it on the road next week to see how the hills go.
For the manual fuel pump to work correctly, it has to be removed, cleaned and the two "O" rings replaced. I never prefill the filters as it may introduce contamination as the fuel, container and funnel are not clean. With the manual pump working correctly, filling the two filters is not that hard. Below are the part numbers for the filters and an exploded view of the manual pump and the check valve that was cracked allowing air to be introduced into the system. Tom Hall has a site showing how to install an electric pump to quickly prime the system on a MCI bus with an 8V-71 Detroit. Will work nicely on a U300 also (or most any coach) Tom Hall (https://www.coachconversioncentral.com/tomhall.htm)
Pierce
Thanks again Pierce! I suppose the risk of dirty fuel in the filter pre-fill is low, but certainly exists. The by product would be clogged injectors. Not fun.
I will plan to service the manual pump as you suggested when back at home base for Thanksgiving.
No, the electronic injectors are really expensive. I replaced a mechanical unit injector on my 8V-71 and it was just under $50 but I could have replaced all of them for the cost of one electronic unit injector.
I took the little pump to NAPA and the counter guy came up with a couple of O rings for $0.10/ea. If you ever need the check valve, you have to shop around as most stores want $65 plus for it. I went to a logging truck company where it was about $35.
Since diesel is lighter than water, pressurizing the main fuel tank to 4 psi will raise the diesel about 11 feet or translating, plenty to push fuel to the one turn loose secondary filter.
Pierce