FASS question

[Jed]

I have the 150 gph system, installed jan. 05. about 35,000 on FASS and 115,000or so on truck.

I have always had about 14 to 15 lbs of pressure and changed filters @10,000.

Friday on the way to work I noticed that I had 10lbs at highway speed. OONO!!

So at lunch I start truck and 15lbs again. OK thats good right.

After work I start and 8lbs OH CRAP.

I call my dealer and he says to check the spring and the ball and tells me that it is on the intake side of pump at the rear of the assembly and the spring and ball are in the line. Well I remove the line and no spring and no ball.

Does anyone know where this is located I tried to find the

fass website but all I get is some propane injection stuff.

I could really use a drawing of what I am looking at.

Thanks for any help

Jed

 

[steved]

The spring and ball are under the fitting for the return line to the tank... not the intake from the tank... it will be the line that returns fuel to the tank... should be one of the two lines facing the front of the truck in a typical installation.



You have an older unit, might want to ask Diesel_Dan if that has removeable brushes and meybe get a set on the way... that's what it sounds like is that your brushes are hung or worn out. Or you could just be sucking a lot of air.



steved

 

[Jed]

Thanks Steve I think I figured out which one of the lines I need to look at. I will go home at lunch and try. The fuel tank is full so no room for air. Do I need to drop the whole unit to get to the brushes to inspect and are the brushes common enough to replace them locally?

 

[steved]

Thanks Steve I think I figured out which one of the lines I need to look at. I will go home at lunch and try. The fuel tank is full so no room for air. Do I need to drop the whole unit to get to the brushes to inspect and are the brushes common enough to replace them locally?

I don't know about local replacements... but from what I have read you can get the brushes out without dropping the unit...



steved

 

[wcjp]

The guy I commute with had the same problem with his Fass. Bad gauge.

 

[Jed]

Ok, update time. I pulled the spring and ball out spring looked good with plenty of tension, ball was a plastic material and was not as smooth as I would have guessed but it seemed ok. Reassemble Started truck 8lbs. damn. So what next? I was able to get to the brush holder so I figured the next move was to pull the brushes and inspect. I managed to break the plastic slot and not move the holder Yea!! Now were getting somewhere... So I guess tomorrow I will drop the whole thing and dig the brushes out.

 

[LowFly]

The guy I commute with had the same problem with his Fass. Bad gauge.

Yeah, i have to say that alot of gauge problems are blamed on the FASS. BUT not always the case.



FASS diagram



Here is the side of the FASS you want to be on. The spring is under that fitting just above the fuel filter..... labled "Adjustable PSI Regulator".



Motor pitch changing? Usally with that much drop... you would hear the motor draging. Look at all your NPT connecitons..... check for air leaks... ... . do the 5 gallon bucket test... might be a intake restriction..... crud on the pick up screen.



Check out the trouble shooting man in my sig and see if that is any help. PM me for any more info... ... .

 

[WCounts]

Folks with fuel pressure problems with FASS or AirDog that don't mind spending a little money can install a bypass regulator. With a guage mounted at the regulator you can easily set your pressure. The guage at the regulator is more reliable than a guage in the cab with a isolator in line.

 

[Jed]

Thanks, but I dont need to regulate I just want my 15lbs of pressure back. While it is a possibility that I have a bad guage it seems unlikely at this point. I am going to do whatever Diesel Dan says to do next. Without the gauge in the cab I would not even know I had a problem.

 

[WCounts]

The brush caps are easy to break. If the brushes are worn out you need to check the commentator for wear and clean the carbon out. If you don't have high milage and the motor is running smooth the brushes are not the problem. Have someone look at your fuel pressure gauge and pinch the return line. If the pressure goes up you have a regulator problem. If your guage doesn't move you got a gauge problem.

 

[steved]

Folks with fuel pressure problems with FASS or AirDog that don't mind spending a little money can install a bypass regulator. With a guage mounted at the regulator you can easily set your pressure. The guage at the regulator is more reliable than a guage in the cab with a isolator in line.

While this works for regulating a high pressure issue, it does nothign for a low pressure issue.



And FWIW, I have seen more than one regulator starve for fuel on the down stream side... they are a restriction.



steved

 

[WCounts]

The bypass regulators give you full flow without restriction. You can see straight through them.

 

[Jed]

Talked to Diesel Dan and he said to pinch off the return line and do the 5gal bucket test. So I pinched off the line and motor on FASS really bogged down and pressure went from 8lbs to 9lbs. Ok this is good or no good? No good I think. I will get some fittings and try the 5gal bucket test this weekend unless I can figure out how to get to the top of the tank to get the pickup hose off.

 

[LowFly]

HUH... . pressure should have raised alot higher than that. I would next check what you are going to do. The "bucket test". That fitting on top of the tank is a cinch to get off if you used the quick disconnect. I dont feel you need get fittings to make it work. All you have to do it follow the line up to the top of the tank. Find the quick disconnect. at the end of the disconnect, there will be a black plastic ring of sorts. Push in the hose with your palm, while at the same time pull back with your index finger and thumb on the plastic ring. Hold in the ring and pull back on the hose. It should pop off. Thats it! It goes back on even easier... . just push it back on until it clicks. I would suggest taking your truck over to Steve and let me take a first hand look at what is going on if you are close enough. He might have some good suggestions being there in person. Or just hold out until next week... ... more info to come for all owners of the older FASS motor... ... ... .

 

[steved]

Sounds like a bad guage to me... I have already had this happen...



steved

 

[WCounts]

Sounds like a bad gauge to me. When he pinched the return line enough to bog the pump down his guage should have pegged.

 

[steved]

Sounds like a bad gauge to me. When he pinched the return line enough to bog the pump down his guage should have pegged.

Exactly...



steved

 

[LowFly]

Talked to Diesel Dan and he said to pinch off the return line and do the 5gal bucket test. So I pinched off the line and motor on FASS really bogged down and pressure went from 8lbs to 9lbs. Ok this is good or no good? No good I think. I will get some fittings and try the 5gal bucket test this weekend unless I can figure out how to get to the top of the tank to get the pickup hose off.

Do you have a fuel pressure isolator on the gauge circuit?

 

[Jed]

Yes there is an isolator. I am rigging up a gauge to test the FASS pressure at the port on the pump. I will do the 5gal bucket test this weekend. Does anyone know of a good gauge set up for the port on the FASS?

.

 

[Fishin Guide]

There have been a fwe issues with the 150GPH pump sucking the module dry. This results in motor pitch changes and possibly even cavitation in the system.



FASS's fix is a seperate 1/2" standpipe and bulkhead fitting to draw unrestricted fuel supply.



So, what I am saying is that your gauge may be right. The pump may be working correctly. You may have a restriction in the tank.



FWIW.



Dave