I have a 3126 in my truck. When I started it this morning it started for a bit then shut off. It turns over but I suspected fuel problems. When I cracked the bleeder on the filter and turned it over there was no fuel. Then I took the line off leading from the pump to the filter and still no fuel. Any ideas? Serial -8yl92142. Ar-197-1131. Core ar-173-1332. Oem-c01-00023-309. Famliy-Ycpxh0442hrk.
That sounds like fuel not getting from the tank to the pump. I'm not familiar with the 3126, but on at least some 3116's the first filter was close to the tank and under suction from the pump which then pumped through the second filter and back to the pump. The point being that an air leak between the tank and the pump would cause it to not prime (easily) because the pump was mounted high on the engine. Put some LIGHT air pressure on the tank and loosen the lines at the pump to bleed the air out, then try it again.
There are 2 filters, one down low on right side and one on top. The one down low has wires leading to it. Is that an electric pump? When I turn on the key there is no sound or vibration.
These are the filters. Sorry about the double photo, that is the one on top. The last one is the one with the wires.
The 2nd filter looks like the water separator. Maybe the wiring is connected to the water detection switch..? How about an engine Serial Number to take the guesswork out of it..?
That's my guess. Or a fuel heater? if those wires are as big as they should be with a nut like that for an electrical terminal. They put plastic or something other than thin sheet metal to hold the water. The older style had a bigger filter with the other end up, that got a little water in the bottom as it was supposed to, and rusted a tiny pin hole that wouldn't leak because there's rust in the way, but would suck air... The light air pressure to prime it is still my suggestion, I guess just as well without a serial number
I have to come to the defence of the OP here I'm afraid...
Ooops ....... that's embarassing.... maybe a visit to the optician should be in order..? Based on the engine S/N it appears that what we think is a water separator belongs to the Freightliner chassis not the engine. It only lists a secondary fuel filter. Also the fuel transfer pump is not electric. It's mounted right on the back of the Unit Injector Hydraulic Pump.
I know this thread doesn't really need another opinion, but FWIW I think there's a good chance it's going to turn out to be (another) HEUI pump failure.
The frame mounted water separator looks like it has a fuel heater to me. These 3126's in trucks usually have a cheesy aluminum plunger type lift pump on the back of the HEUI pump (not the gear pump as on industrial applications), they don't have much for power or flow so any little suction air leak will cause this issue. Another thing to look for, FL series Freightliners were famous for putting a small inline lawnmower style filter under the cab in the fuel line from the tank, but i've only seen them on Cummins powered trucks. I'll never understand why CAT made that cover plate where the primer pump would mount on the secondary filter head, I don't have the part number but the stubby style primer pump will clear the hood and is always nice to have!! When were these fuel filters last replaced?? Did you have any power issues??
I had an FL80 WITH a 3126 and it had the small in line filter....it was a major PIA to replace, you could see it, and you could touch it with one hand, but it was next to impossible to get both hands on it to change it.....so it could be there, look under the cab and follow the fuel line from the tank.
Thanks for all the info. It is on a frieghtliner. Fl 70. I will look for the small filter that you all talk about. I replaced both filters last year. But i was having starting problems, it would start and then stop, but after a few times it would be ok. Now it will not start at all. I am not sure where the electric pump is. Thanks again.
There is no electric fuel pump on these trucks, just the mechanical one on the back side of the HEUI pump. When the truck was running did the check engine light happen to be on or come on at any time while driving? I would pull the codes just to see, you can get it to flash codes with the check engine light, It's been a while since i've done it, but (I think) have the key on then turn the cruise control switch on, then press and hold the cruise set switch up until the check engine light starts to flash and release, count the flashes then it will have a short pause then count flashes again. So if it flashes twice then has a short pause then flashes twice then a long pause would be code 22, just an example... Try that just for fun and report back.
There was no check engine light.
I found some sludge in the line to the water separator. I blew the line out and put new filters on. now I am having trouble bleeding the lines. and ideas?
No, I wouldn't have any idea how to do that:beatsme
As there is no priming pump and the transfer pump is mounted on the back of the HEUI pump you're going to need some good strong batteries and a set of vice grips. Clamp the vice grips on the fuel return hose between the engine and the tank then crank the engine over on the starter. When the engine fires give it about 5 seconds and then remove the vice grips. If the fuel return hose is not too accessible it would be an idea to have a second person to help.
It will prime better if you take the line off coming out of the primary filter and blow in the fuel tank until you get fuel through the filter. Use a blowgun with a rag wrapped around it in the fill spout to pressure the tank. Or go get a hand pump and mount it on the second filter. You may need it the next time it stops on the road.
I will try tomorrow and let you know.
My favorite thing to do to prime a stubborn engine is to rig an electric fuel pump in it somewhere feeding into it where it can also bleed back to the fuel tank, go have lunch, and come back and it is usually pretty well primed by then. Not sure if it applies to this particular situation but it's worth a shot.
I did what mobiltech said and put a hand pump on the top of the second filter and it worked. To be honest, I found a guy that is very good with cat engines and he said it is a frieghtliner thing not to put a hand pump on the filter. He had a hand pump that fits on top of the filter. If you look at my picture of the filter you will see a cover with two bolts, remove those bolts and cover and his hand pump fit right on. Worked perfect. Thanks for the help.