cat 3406b

coxy · March 20, 2018, 04:42:21 PM

today it lost fuel pressure we changed both filters and still in the red runs ok but not as much power and when you hit the jake brake the pressure goes to almost nothing any idea what it is

starmac · March 20, 2018, 04:55:57 PM

Transfer pump, not sure what the jake would have to do with that though.
Do you gave a gauge on it to monitor the fuel pressure, if so what is it reading at an idle?

coxy · March 20, 2018, 06:04:25 PM

ya the pressure reads red all the time but as soon as you hit the jake it goes to almost nothing even at full throttle with no load it reads half in the red at load pulling a hill it reads half red i thought the gauge took a crap every thing has been good till this AM errrrrrrr

mike_belben · March 20, 2018, 07:57:04 PM

I do not know that pump at all but im gonna guess it is a plunger off a cam lobe? If its a spring and piston style like a mechanical cummins 6bt then you can have busted a spring or one of the little one way valves broken.

If its a gear style lift pump then maybe a bad relief thats letting it bypass pressure. Busted spring, trash in the seat etc.

Does the high pressure gallery have a return line back to tank with a regulator in line? On most bosch inline pumps they call it an overflow valve and its a spring loaded steel check ball in the banjo bolt tee fitting. The overflow valve spring preload determines the pressure inside the plunger gallery. If you shim those up and dont get a pressure rise, it suggests a weak lift pump or flow reduction upstream of the lift pump.

Delaminated internal hose on the suction side? Gummed on sump screen inside tank? I had styrofoam and a sponge floating around inside a tank once. Plugged up the drawstraw now and then.

Again, just general mechanical pump considerations. Sorry i cant be more model specific

starmac · March 20, 2018, 09:32:31 PM

Well if it is running in the red all the time it will naturally fall off some when the rpms drop, But the only think I could think of is the jake drops the rpms drop quicker,, so it seems like it is what is causing it.
It is rare, rare and even rarer than that for a fuel pressure gauge to still be working in anything any where close to the age of a B model.

Any shop should have a good gauge to check pressure right at the engine and tell the problem, I have a quick connect on my e model, I keep meaning to put one on my b model, so I can check pressure when servicing.

Firewoodjoe · March 20, 2018, 10:08:43 PM

Do those have a return line you can pinch off with vise grips? I know on a series 60 that will increase pressure to test it quick.

starmac · March 20, 2018, 10:19:50 PM

Yes, they do have a return line, but you can test it without pinching it off. a good gauge will tell you exactly what it is doing.

mike_belben · March 21, 2018, 04:04:42 AM

Hes saying to test if the pump is the issue. Just gotta be sure its not a wire braid hose youre clamping.

Jake will drop revs and further reduce pump flow so its still inline with the premise of low lift pump pressure. Too much internal leakage or twoo much restriction on the suction side. I have seen algae plug up a drawstraw pretty good too.

Firewoodjoe · March 21, 2018, 05:16:41 AM

Most trucks have vise grips under the seat but not a ready to plum test gauge.

ga jones · March 21, 2018, 03:04:03 PM

Internal hose collapse. Common with the B

starmac · March 21, 2018, 04:20:03 PM

I doubt cat ever made a b model without a test port.
The fuel lines deterioting is common on any of them as they get older, and the b model has not been produced since 93 or so.
Generally you can find evidence of bad fuel lines in the filters. Many b models had a screen for the primary filter, have you pulled it out and cleaned it?

coxy · March 22, 2018, 06:34:02 AM

I'm sorry guys its 3406e don't know what i was thinking when i put b in there i think we got it fixed it has always had a Baldwin filter on it and we changed it to a napa gold the only thing that was gold about it was the price 46$

we put a Baldwin filter back on it was fine i had some trouble with napa filters in the past with my tranny over heating in my cat skidder went back to a cat filter and things was fine the cat guy told me its because of the different micron filters

Skeans1 · March 22, 2018, 09:00:48 AM

For the price of a napa or baldwin filter you can get a 1r-0749 or 1r-0750 filter heck you can get them cheaper then the off brand filter.

mike_belben · March 22, 2018, 12:47:17 PM

That little letter changes everything dont it?

coxy · March 24, 2018, 07:02:29 PM

ya it changes the price on parts in a big way also :D

starmac · March 24, 2018, 07:28:43 PM

I buy several fuel filters at a time for my E model, but I have never paid that much for them, and I buy them at the KW dealer and cat filters only, that price seems spendy to me. It has been a couple of years since I have bought any, and I don't remember the price, but I can assure you it was not 40 bucks a pop.

What kind of pressure is your pump putting out, I like mine to be close to 100 pounds at idle and get a little over at 1500 rpms, I have had to shim a couple to get the pressure right, some people just stretches the spring too though.