Repeating CAPS Failures - Need Help

[TR4]

Originally Posted by dons2346

I have cracked the pump open and so far, all I have found is the cheap POS gasket that breaks down and causes the leak. When I get more time, I'll tear it apart further but so far, no screen.

Don,
When you get the pump apart, could you take some pictures of the internals. I'd be interested to see how the the manifold is plumbed for the fuel return to the tank.

Bill

[dons2346]

Originally Posted by TR4

Don,
When you get the pump apart, could you take some pictures of the internals. I'd be interested to see how the the manifold is plumbed for the fuel return to the tank.

Bill

It will be a week or so as we are on the road right now. I do plan to take it apart as far as I can

[gmgr]

'finally' placed order for the FA fass.. ordered at SummitRacing on-line(free shipping & same price). Checked first with fassride to be certain they are legit dealer.
The plan is still to place pump at tank for positive flow. This is info from 2 techs at fassride.com:
1. there should be no restrictions from tank to fass (no (1-way)check valve-though gave explanation for valve to keep fuel in line)-or
primary filter (1 said Davco should be placed after pump; the other said if try should change out if too much 'restriction' causing pressure drop)
2. removing the inline (pre)filter would void the warranty..said 1.... hmmm
3. will need additional readily available push lock fuel line (kit comes with 14')

[dons2346]

Tore apart the lift pump yesterday, not a lot to it to fail except the gasket. There is a simple wobble pump with metal vanes, a screen to filter out big chunks. My screen was totally clean. Down in the hole, you can see something that looks like a one way valve, I couldn't get it out. The mounting plate has various ports to plumb hoses. Not real exciting. The motor is installed with a crimp band so I didn't remove it. It is nothing but a simple 12VDC motor that turns the pump vanes. Inside of the pump was totally clean, just a crummy gasket that was falling apart.

[TR4]

Don, thanks for dismantling the pump and posting the pictures. I now see how much restriction the CAPS encounters pulling fuel through it. Now add over thirty feet of fuel line, one or two fuel filters. In a perfect world the CAPS is riding on the edge. Now add a dirty filter or a loose connection allowing air to enter the fuel system, starving the injection pump.

Bill

[dons2346]

It would be interesting to see what the flow rate is of the pump both GPH and pressure. It would be easy to do with the pump out of the system. Just hook up a few hoses and put 12VDC to the motor

[jleamo1]

Well that explains it all! Great information Don!
That poor pump is put through a lot, especially on a coach, no wonder they fail so often and have been redesigned so many times. Don't forget the heat where its located, my factory fuel line routing would have added to the heat issue also. Its a wonder it made it to 62,000 miles when the original pump failed

[Startech]

Add me to the club. Last summer while traveling I-70 in Colorado, I was way under powered and couldn't make it over the passes. So, I had to turn around to go to a Cummins shop in Grand Junction. They replaced my fuel filter and the injector control valve module. After 3 days there, I got about 70% of my power back and was ready to get out of there after about $4k. Now that I have only 2 months warranty left, I decided to see if another shop in Farmington could get me the 30% back. $800 later, they said all was good, no codes, no leaking lift pump and nothing under warranty. After reading this thread, I am going to do the Fass mod. But they did say they found one problem on a test drive, but had no idea how to fix it. They said under wot, I had low intake manifold pressure. They said it measured 20 rather than 27. Maybe I should start a new thread, but wanted to ask here due to the wealth of knowledge I am seeing. Thank you.

[Dr4Film]

Is it possible that your CAC has too many leaks? Or possibly some leaks around the turbo?

Dr4Film ----- Richard

[Startech]

Seems they checked everything except the cac. I don't want to sideline this thread, so I will start another one. Thank you.

[dons2346]

Yup. Low boost usually points to a leaking CAC

[gmgr]

Originally Posted by gmgr

'my' service guy is loving this, but.... hasn't done this installation -Fass, gauges,davco and says he can't give me a time estimate... -- lord, what is this going to mean ?$$$$$

ended up with fass install similar to Smitty77, no gauges or davco... I understand shop used fass techs more than once, along with call in to Cummins... the end result was labor bill of some $2600 for me... they tell me it is running great ! (sure hope so)
Happy 4th everyone !

[RVingDutchman]

Thank you Brad @ Protech Diesel in Kamloops BC. He Got 'R Done for us...... I mean have the FASS pump installed the (old) lift-pump bypassed ! he said they also eliminated quite some excess fuel plumbing and the second (rear) fuel filter.
After which he eliminated the pump code and >It stayed OFF< then we went for a test drive and it behaved awesome, (and all that in barely 5 hours too including having to run that return hose al the way to front to the tank filler tube!, Now we have great power, good take off, fuel mileage seems OK , So I drove it home, 58 Miles and all seems well. Lets hope we're not to soon !!!!

Thanks to every one here for all their help and suggestions, This community is so awesome and I will miss it now that we have to sell the MotorHome, but such is life, and then you move on.

Thanks again everyone you're awesome.......


The Very Best Regards,


Ed & Debbie

[dirt racer]

ColoradoHRE,,i and a failure last year with our 8.3 isc about this time of year.
Left SE Iowa on a very hot day to head to vegas area and Rv starts bucking close to omaha. Went to omaha cummins and they thought they figured it out and made it another hour 2 days later and started again.
Instead of paying for a 2500 tow bill to home i drove it home,, took us 10.5 hours to make a 4 hour trip.
Cummins in DM replaced some pumps parts and said it was fixed.
2 trips later and another fail, took it back and they fixed same issue under warranty.
Drove it about 200 miles and no issues, started to head to hershey park in oct for big swap and get to Indy and started bucking again but not as bad so head back home.
Back to cummins it goes and they then think its ecm taking out parts in pump, replace ecm and pump parts again and check all wiring on motor, motor to fuse box and box to switch, load tested fine and they drove it 3 hours with no issues and say its fixed.
Before I put it away for winter i decide to put new lines in, drop tank as far as i can to get my arms and head up in there to work on stuff and find return line smashed between tank and frame rail,,id say since day one cause it didn't look to me like tank had ever been dropped and according to newmar with what they say they look like the lines are original.
Fixed that and drove it a little and put it away.
I believe this was the issue from the beginning so if you have more issues have someone check that out.
I bought this RV last march and pump and lift pump was replaced,,not sure when but pump and lift pump has a build date of oct 2014 on them.
I'm going to put the fast pump on and have read this forum back and forth, lol!
i hope your issues are all figured out,,sucks to be sitting on the road when your to be having fun.
i have a question for TR4 or Jleano1 also. It was said there is a write up for how to wire in relay for factory lift pump to trick ecm to think its working.
Would greatly appreciate any and all pics and part #s for relays i might need to do this.
Have the pump already and haven't yet decided to put it next to tank or between primary and secondary filter. Fass send a filter with the pump but not sure if its what i want to use or not.
So many great ideas here its hard to decide but i believe positive pressure to the caps pumps has to be better.
Its like sucking through a straw compared to blowing through it.
Have a great 4th everyone!!