Lift pump or computer issue?

[zzman]

I have a FASS lift pump since Sept 2009. Never had an issue so far. Last week while returning from a 1200 mile trip, it appears the lift pump quit running and the truck lost power but still ran barely.

I changed the fuel filter (appeared OK), cleaned the air filter (it was real dirty) and added a 100 gal qty of Diesel Clean to the 35 gal tank (hopeing to clean any gunk out).

It ran good for a while (a day and a half) then started again. I pulled off the side of the road and this is when I realized the lift pump seem not to be running (while still idleing). The pump was almost too hot to the touch. I set on the side of the road for an hour with engine off (attempting to cool off the pump). It ran fine until the next day (about 400 mi) it started again. I pulled over and turned the engine off for about 30 seconds. Started up and it ran fine all the way home (about 50 mi).

I have talked with FASS and they suggested some testing to be sure it is the pump. The amount of fuel in tank makes no difference, the towing weight makes no difference, I have connected a by-pass direct power line to the pump for the next time it quits. They suggested it may be the computer limiting the amount of volts to the pump. Haven't tested this as of now.

One common thing is every time it quits, it is close or above 100 degrees outside.

So here I am looking for help again, wondering if anyone has experianced this before.

I did learn that the CP3 pump will pull through the FASS pump enough to drive.

I appreciate any and all your comments, suggestions or remarks.

Thanks

 

[AH64ID]

Sounds like a pump to me...

 

[zzman]

I think so too, but why would it run perfect when it does run? It seems it would be weak or make a bad noise or something if it was going bad.

I'm starting to lean towards the voltage to the pump. I wish I could make it mess up, no telling when it will start again. This isn't very good for a reliable Hot Shot service.

 

[AH64ID]

Pump is starting to fail, and when it overheats it can't run.

To rule the voltage out, since the the computer should only be giving voltage to a relay and not the pump, hard wire the pump when it fails and see.

 

[zzman]

Yep thats what I did, now duty calls, got a 750 mi trip to try it on. Be back Friday and we'll see.

 

[zzman]

Well 100 miles down the road and the switch doesn't help.

Only thing that helps is to stop and turn off engine for a while.

Then it works great, it was 104 degrees today too.

My load brings me back thru the house, I'm going to wait til midnight or so to finish (a little cooler then).

I guess it is the pump. FASS says their policy is you send the bad pump back to them and they check it, if bad they send you another. Now that sounds like a week or 2 to me. Or they send me another for 275. 00 core charge and they refund me when the old pump checks bad. I'll go that way I guess, I wish there was a FASS dealer with stock close by.

104 !!!! and it's barly summer

 

[steved]

The FASS pump is powered through a relay with full battery voltage. The relay is triggered by the computer. Its either on or off, the relay doesn't take a whole lot of voltage to engage, and the relay doesn't partially engage.

My gut, the pump is failing... mine died last fall, and it did a batch of weird stuff before it finally quit altogether. But I also was able to drive 2100 miles home on the failed pump since they have a built in bypass... it almost sounds like it has a restriction in the pump itself that is stalling it? In other words it has a mechanical problem, not an electrical problem.

Just my thoughts...

On edit: I decided to try a different pump this go around, and went with an AirDog 100. If it lasts 180k and six years, then it will prove itself.

 

[zzman]

FASS is sending me another pump.

The old one has I guess 130-140k miles on it.

They said the new one is an updated one from my discontinued model. It is suspose to be quieter running.

Genos Garage says this is the second one that he has ever heard of going bad in his 4 years.

Thanks guys

 

[zzman]

Installed the new pump today. Actually it is the same pump as my old one.

It seems to pump alot more fuel than the old one and it is just slightly quieter.

I judged the qty flow with the filter drain open.

I'll probably get a run tomorrow to test it out. It's a little cooler outside too so maybe that won't be very good for testing.

 

[zzman]

Well, that wasn't it.

It still loses power.

I have the actuator on the cp3 coming, maybe that will work.

Man! I just hate these trial and error processes.



I have learned that If I pull over and drain the filter, it will work for a little while (10-20 miles)?? What is weird, when the drain is opened, there is little or no fuel coming out, only air or maybe it is a vaccum release.

I think I will attempt to drop the tank and check for blockage or whatever I can find.



Does this sound familiar to anyone???

 

[zzman]

DROP the TANK

I haven't a tool to reach the front clamp nut. I need I guess a 6 or 7" deep socket.

Crap, when are things going to get easier? with age HAH



maybe I'll wait for the actuator, maybe that'll solve it all Oo.



(note to self: sell truck as-is)

 

[AH64ID]

No fuel coming out with the motor/LP off is normal, it's a closed system and takes a long time to drain.

Very interesting that draining the canister works, that doesn't make me think FCA but who knows.

Have you talked with TC Diesel?

 

[zzman]

it seems the act of draining the canister may not be the key after all, it is probably the fact that each time the engine is shut down it allows the "High Pressure Valve" to cool slightly enough to hold pressure again. This is the idea that TC Diesel has. What he said makes the most sense from all this.

Normally when I leave on a run, I never turn the truck off until I return. In some cases this could be 48 or more hrs. So yesterday I went on a 600 mile run but I turned off the truck at each location (maybe 10 to 30 minutes ea X5) The truck ran great all day. When I talked to TC he wanted me to test the reaction time on engine after re-connecting the FCA while it was running. 25 seconds was the time, he says he believes the High Pressure Valve on the rail is not holding the pressure. He states when the fuel gets hot the Valve gets weaker (if I recall right), this makes all the sense on how my truck is running.

I recieved my stuff from Genos yesterday, well the packing slip says I did, was suppose to get a FCA but somehow they sent a fuel filter/canister for 07/09 6. 7 ????? when it rains it pours I guess.

Well for now I will wait on the Pressure Valve that I'm going to order from TC Diesel today. Need to give Geno's a tounge lashing and see what they can do.

I think we're getting there.

 

[zzman]

update:



Installed the pressure valve and it made the engine a little quieter (less diesel ping).

Then the FCA came in and installed it (no noticeable change).

Haven't been out on a run yet, but I will drive it normally and see what happens. It is still 100 plus degrees outside so that should give it a good test flight.

Geno's gave me a 20% discount on the filter that was shipped in error. It will work on my son's truck. They overnighted the FCA.

 

[steved]

Did you verify the fuse holder on the FASS isn't corroded and that the FASS relay is not faulty? It sounds like the relay is cutting out when it gets hot... although when my FASS died and I drove it home 2100 miles Without any change in the way it ran.



I would definitely check/change the relay ($5 at any radio shack

).

 

[zzman]

I did have the FASS hooked up with a direct circut that I could switch on when it started to faulter. That didn't do any good either. I assume the relay would be good and any connections.

I think T&C Diesel may be right with the Constant Pressure Valve on the rail. He states it is probably weak and gets weaker when it gets hotter.

I'll see with my first run what it does.

Thanks