klx650a2

I was towing my dump trailer (3500 lbs) and accelerating through the gears and it sucked the FP down to 3 psi, then I backed off and it went back to 15 psi. Once I got up to speed, I hammered it hard, FP dropped to 10 or so, could never get it to go lower. What happened? I just replaced my fuel filter. The truck starts and runs fine and gets great fuel economy. I do not have the big line kit on it yet, would that make a difference? I have not changed the strainer yet either, but all other times the FP is great. One thing I have noticed is the pump sounds like there is cavitation. It did it last year with winter fuel and went away in the spring and summer. Does it matter that I'm running 2 stroke oil also? It claims it flows down to -40C or F (same temp).

klx650a2

No one has any ideas? Did more testing yesterday, can suck the FP down at will after about 3 or 4 seconds of hard acceleration at about 2200 rpm. Once I back off and hammer it at highway speeds all is well.

imbodie

I'm installing a FASS HPFP today.... the install kit (haven't gotten it yet, but its out for delivery) shows to have a pre-filter for the FASS unit... a silver canister that goes inline before the FASS pump. I've seen these filters in the local autoparts stores....

Have you changed that one yet?

I'm not sure what you mean by the strainer....

-Tim

dodgediesel

How full is your tank? What type of gauge are you using, mechanical or elecrtic?? I backed my weird fuel pressures up with a good old fluid filled mechanical gauge. This let me know my electrical one was out to lunch...

klx650a2

I have the pre-filter before the lift pump and have not swapped that out yet. But if it was plugged, wouldn't my numbers be lower across the board?

My tank is about 3/4 full, am using a mechanical gauge with fuel right up to the gauge. Not a fluid filled gauge and no antifreeze isolator.

I'll do the strainer this weekend and see whats up. Maybe do the big line kit too....

imbodie

I would think if that if the pre-filter was getting clogged it might restrict flow at peak demand...
But then... how often do these need to be changed? I just finished with my install.
-Tim

dodgediesel

I would suspect the pre-filter being the issue my friend..

J Lent

Yepper, also....did you drain the water seperator? How much oil you running?

klx650a2

Well, swapped out the pre-filter, poured diesel all over my winter jacket and in my eyes. Boy, that REALLY burns. No difference in the FP numbers. I'm thinking the pickup screen might be plugged. I am also thinking of back flushing it with some compressed air to see if that helps. Hate to drop the tank for nothing.

Yup, no water in the seperator.

I'm running about 16 ounces of 2 stroke oil per full tank of fuel. Going to try no oil the next few tanks. (but I really hate the loud injector knock)

J Lent

Possible algae contamination?

klx650a2

Would there be an algea issue if I'm not running any biofuel? I only get my fuel from the flying j and they go through HUGE amounts of it. They always have at least 40-60 trucks sitting in their lot. I am running a winter fuel conditioner and anti-gel.

http://www.dieselservices.com/html/b...rmor/index.cfm

klx650a2

Alright, seem to have the issue addressed. I filled up with fuel friday evening and put in 34 gallons of fuel in a 35 gallon tank (no low fuel light, not happy about that). Did not put in my winter diesel fuel conditioner that contained anti-gel, but put in the summer(can run it year round as well). No pump noise and cannot seem to suck down the fuel pressure. Must have been something in the antigel that caused the cavitation?

I'm happy now!!! And its getting cold too...

turbo2

I had the same problem after picking up fuel at a station. I had intermitant fuel pressure only a lot worse than yours. I checked for water,none, put on new filters, no change. I ordered a vulcan draw straw. While waiting for it to come in I bought a can of heet , the kind for diesel engines, an I thougtht why not give it a try? It cleared up the problem and I still have the draw straw in my shop. I was wondering if anyone else out there has tried this? I have my pressure gauge built into my attitude gauges so it is electric and I am still suspicious of it, but the problem cleared up when I used the heet. Go figure.