Sea Bass

I got a quick question for ya. Yesterday, I noticed my FP dropping down to 10psi at random when I was driving in traffic. Normally, it stays at 16 and I can barely pull it down to 14. It would hit 10 with very light throttle and then come back up to 16-17psi. Sometimes when it would fluctuate I would punch it and the pressure would come up to where it should be. This is exactly what it was like when my LP died. I don't get it.

Also... a few times when I would try and bumpstart my truck I couldn't hear the fass cycling.

What do you think? Electrical? Brushes? I've only had the fass about a year.

I appreciate any advice you can give me.

Doug

MSquare

Doug,

Did you check the ground connection?

If it's only a year old, I think you have the new type of brushes.

Where is Diesel Dan?

crobtex

He's camped out in a cold and wet East Texas this weekend.

Like he said, check the electrical connections first. If all is well there, I would also check the fuel filter and lines for air leaks. Mine is a year and a half old, and it has never missed a lick. Since mine is the old style brushes, I have a set under the rear seat for emergencies.

BCSCUMMINS

Do you have an electric fuel gauge if so might be gauge or sender or if with manual gauge could be the isolator if you have one. If it was a filter I would think it would be constant low psi all the time. Can be wire connection or fass could be getting ready to trash on you.

Tate

Mine has done that occasionally, although never down to 10. 12 I would see if I got on it hard in 3rd, and it would come back up. I'm betting it was because my fuel module in the tank was broken, and would slosh around with the fuel, and would take a gulp of air. I haven't gotten it back on the road it, to see if I'm right.

Sea Bass

I'm going to check it out tomorrow. I'll go through and clean the connections. I did try to PM diesel dan first but he's blocked that function. I'll let ya know what I find out.

Thanks guys

Diesel-Dan

HUH....search function never brought this one up for some reason. Like Crobtx said...was camping out in Alto, Texas this weekend so didn’t have a computer on me!

Gauge: Electric or manual? Make sure this is reading correctly

Do you have a draw tube in the tank? If yes, how low was your fuel? If it is low enough, you can suck some air and pressure will fluctuate. Might make sure its about the width of 2 quarters stacked flat from the bottom of the tank.

If you have the stock module, might check for restrictions on the suction line to the FASS. This would cause pressure fluctuation as well.

Some times when you run the truck and then shut it down, then bump the engine, the pump will not run. You have to let it sit for about 3-5 mins before it will work normal. Don’t know if this is a safety thing written into the software or not.

Another question: Is this a FASS or HPFP?

Rodram2002

Doug, Mine will do the same thing when my tank get's low on fuel, for the reasone as above with the draw straw.

Hope ya get it figured out.

Diesel-Dan, can we get springs to bring the fuel pressure up to about 25-30psi?