Community Forums

rfguy · 05-22-2016, 09:21 PM

I have a cummins ISC8.3 and just changed the engine oil and oil filter. They recommend changing the primary (FF5636) and secondary (FS1065) fuel filters at the same interval. Other than filling them fuel before screwing on is there a purging process or just start the engine and let it run the air out?

Thanks for any tips.

RV_Tech · 05-22-2016, 09:48 PM

Operate the fuel lift pump to help prime the fuel system. Turn the keyswitch to RUN, but do not attempt to start the engine. This will cause the engine control module (ECM) to operate the fuel lift pump through a priming cycle which lasts at least 30 seconds. Cycle the lift pump several times by keying OFF, waiting 10 seconds, and keying ON again.
Once the engine is started, slowly increase the engine speed while air is purged from the fuel plumbing.

I STRONGLY recommend signing up on cummins quick serve. It is free for owners and with your esn you will have access to full procedures.

https://quickserve.cummins.com/info/index.html

barmcd · 05-23-2016, 08:13 AM

From what I understand, Cummins says not to prefill the filter. I think the reasoning is so you don't get unfiltered fuel into the system. The priming procedure should fill the filter after it's changed.

RV_Tech · 05-23-2016, 08:30 AM

Please verify on cummins quickserve. Some REQUIRE prefilling and others REQUIRE not.

photopilot · 05-24-2016, 06:49 AM

I replaced my filters Sunday and the filters say prefill on the pictorial instructions. I tried the turn the ignition on trick and it didn't work for me, maybe I didn't do it enough times or wait long enough between. I finally removed the filters and prefilled them using a cheap hand transfer pump from Harbor Freight. Started right up, only a couple of 'burbles' of air.

Walt

Dr4Film · 05-24-2016, 07:07 AM

I have never changed my fuel filters myself on my ISC 350. I always have it done at either Speedco or other truck service centers. All of them have pre-filled the fuel filters with CLEAN diesel fuel.

Cummins states to use the lift pump to fill the fuel filters however when doing that you should only change ONE filter at a time, NOT BOTH. Then once the filter has been fully filled you can start the engine and let it run. Then change the other filter and again use the lift pump to fully fill the filter before starting the engine one more time.

When pre-filling the filters you can immediately start the engine without any difficulty.

It just depends on which procedure you are willing to follow.

BTW, I recently ran my engine out of fuel

but was lucky enough to coast into a fueling station right at a diesel pump

. However once the tank was full (I pumped 110 gallons) it took me several attempts using the lift pump to remove ALL of the air pockets before the engine would not shut off after getting it started once again. My diesel tank holds 128 gallons so there are 18 gallons of diesel in the tank that are not usable.

Dr4Film ----- Richard

jacwjames · 05-24-2016, 07:19 AM

I've changed my fuel filters myself since 2009 after the initial service and inspection of my rig after I bought it.

Before I did not prefill, changed one filter at a time and cycled the key 4-5 times before trying to start.

The last time I changed filter I pulled the primary filter replaced without prefilling and then cycled the key several times. No luck on starting. Finally put some compressed air on the fuel tank and got the primary filter primed then started the engine. What a hassell but luckily I was at home and could improvise a plug for the fuel tank. On the secondary filter I went ahead and prefilled. I used a PVC plug on the center hole and poured the diesel into the outer holes so as make sure there was no contamination.

From now on I'm going to prefill.

rfguy · 05-24-2016, 08:08 AM

Thank you to all. Given the advice to check quickserve cummins site, I set up an account with my esn. I then found the procedure for the ISC8.3. It states
1) clean the area around the filters to prevent contaminates getting into fuel system.
2) for the suction side filter (fuel/water seprator 10 micron filter) pefill with fuel and install (screw on) attach water-in-fuel connector to sensor.
3) for the pressure side 5 micro filter don not pre fill with fuel use lift pump to fill.
Priming using lift pump -Turn key to ignition on only for 30 seconds which is the prime cycle. Turn key off and wait 10 seconds. repeat this several times. Then start the engine and gradually increase RPM until fuel system is purged.