M1078A1 fuel starting issue

[Keith Knight]

Where is your air compressor?

 

[GeneralDisorder]

Where is your air compressor?

My man has a spare engine in his back pocket so I'm fairly confident he's using pics of that rather than his truck


........ But that IS the (unseen) violence inherent in the system. But we can workshop the marketing a bit...... "The timing sensors are very well protected by the air compressor."

 

[Keith Knight]

I saw the timing sensors when I had the pump moved out of the way. None of that is fun to get to.

 

[Ronmar]

On the 2003 3126b M1078A1 the tee is rear of the primary just under the structure carrying the rear cab lock—View attachment 943465

Yep, on the rear of the main filter. I just had someone share a video with me of their 3126 fuel pressure problem, sampled from aft of the fuel filter. Getting ~15 psi at idle and barely passing over 30PSI at 2000RPM, so something is wrong in their neighbor hood…

 

[MatthewWBailey]

My man has a spare engine in his back pocket so I'm fairly confident he's using pics of that rather than his truck


........ But that IS the (unseen) violence inherent in the system. But we can workshop the marketing a bit...... "The timing sensors are very well protected by the air compressor."

Yes bingo. I like 3D schematics. Not those hard to read sheets of paper. . The compressor from the crate engine was new so I swapped it into the truck in August, along with the new PS pump and atmospheric sensor. The oil in it is new so I don't think it's ever been fired up. It's a 2000lb parts bin and interactive diagram. I literally have two of everything. How can one be expected to go thru life without spares?!

 

[Ronmar]

2 is one, one is none…

 

[MatthewWBailey]

I also have this oil leak so looks like I'm doing compressor games for the next day. I think the seal is missing.

 

[GeneralDisorder]

The "seal" between the crankcase and cylinders on that compressor is just paper. But a smear of RTV will work just as well for that. You might get away with pulling that bolt out and putting a little sealant on it. Hard to tell if the oil is emanating from the gasket between the castings or from under the bolt head. Some UV dye and a test drive might tell you after a good cleaning.

 

[MatthewWBailey]

Yep, on the rear of the main filter. I just had someone share a video with me of their 3126 fuel pressure problem, sampled from aft of the fuel filter. Getting ~15 psi at idle and barely passing over 30PSI at 2000RPM, so something is wrong in their neighbor hood…

I see. You mean this. Very convenient! Looks like ORB fitting. I'll see if the hydraulic shop has a dampened gauge.

 

[Ronmar]

Yep, thats it, they made it real easy on the 3116 with a 1/8” npt port. Had an old oil pressure gauge from the junk drawer hooked up in a few minutes…

IMO, this is something everyone should check whenever you change filters… or install a dedicated gauge… I don't think I can possibly count the number of fuel supply issues I have troubleshot over the years.

i am kinda surprised cat stuck with the mechanical lift pump on the 3126/C7. Even ford, when they licensed HEUi from Cat fitted a 60 PSI electric pump/filter unit back near the fuel tank… At least that way any leakage leaves a wet spot a fixed pressure electric pump could be monitored with a pressure sw and an idiot light…

 

[MatthewWBailey]

This is just ALL pointing to that timing sensor code. The ECM has to "sync" to the timing sensors every time you restart the engine. If the signal isn't stable it will take a bit for the ECM to either see enough of the uninterrupted signal OR for it to give up and switch to a fallback strategy. So the rough delayed start is PROBABLY the timing sensors, wiring, or (woof) the trigger teeth on the timing gears.

Here's a picture of the teeth and sensors. Old on right. Newer looking ones from crate engine on left. Same cat#'s 109-7194 and 109-7195. Connectors are clean on the harness.

 

[GeneralDisorder]

Wiring connectors look ok. Probably should check wiring integrity while you have it open. Send a couple amps down the wires (disco both ends - use a headlamp bulb and 12v) and then shake the harness around a bunch and make sure it's solid.

 

[hike]

Yep, thats it, they made it real easy on the 3116 with a 1/8” npt port. Had an old oil pressure gauge from the junk drawer hooked up in a few minutes…

IMO, this is something everyone should check whenever you change filters… or install a dedicated gauge… I don't think I can possibly count the number of fuel supply issues I have troubleshot over the years.

i am kinda surprised cat stuck with the mechanical lift pump on the 3126/C7. Even ford, when they licensed HEUi from Cat fitted a 60 PSI electric pump/filter unit back near the fuel tank… At least that way any leakage leaves a wet spot a fixed pressure electric pump could be monitored with a pressure sw and an idiot light…

I haven't owned a piece of CAT equipment in the last 30 years, but even those simply needed the injectors cracked while cranking. Pumping a primer pump is a new experience for me on a diesel engine on the M1078A1. The last time I pumped to prime fuel was on an outboard motor.

Adding an electric pump near the tank is an interesting idea—

 

[MatthewWBailey]

You might get away with pulling that bolt out and putting a little sealant on it

I'm trying this since no other portion of the seal shows any leakage and there's oil under the nameplate.

 

[Ronmar]

I haven't owned a piece of CAT equipment in the last 30 years, but even those simply needed the injectors cracked while cracking. Pumping a primer pump is a new experience for me on a diesel engine on the M1078A1. The last time I pumped to prime fuel was on an outboard motor.

Adding an electric pump near the tank is an interesting idea—

i wouldn’t “Add” a pump at the tank, I would replace the mechanical lift pump in the governor/HEUI assembly with a 60PSI feed pump and filter at the tank(All electric, no mechanical pump at all) Just so happens Ford makes one of these or I would source an electric pump that will keep my system @60PSI with the regulator just at the full open point…

I think a steady 60 PSI gallery pressure would really help with the low RPM coal roll when I override the fuel ratio limiter to deal with a tailgater…

 

[MatthewWBailey]

i wouldn’t “Add” a pump at the tank, I would replace the mechanical lift pump in the governor/HEUI assembly with a 60PSI feed pump and filter at the tank(All electric, no mechanical pump at all) Just so happens Ford makes one of these or I would source an electric pump that will keep my system @60PSI with the regulator just at the full open point…

I think a steady 60 PSI gallery pressure would really help with the low RPM coal roll when I override the fuel ratio limiter to deal with a tailgater…

What the Ford part?

 

[Ronmar]

What the Ford part?

Well it would be the electric fuel pump and filter assembly used on the ford power stroke pickups…

 

[GeneralDisorder]

FASS has a bunch of external lift pump options.......

 

[hike]

i wouldn’t “Add” a pump at the tank, I would replace the mechanical lift pump in the governor/HEUI assembly with a 60PSI feed pump and filter at the tank(All electric, no mechanical pump at all) Just so happens Ford makes one of these or I would source an electric pump that will keep my system @60PSI with the regulator just at the full open point…

I think a steady 60 PSI gallery pressure would really help with the low RPM coal roll when I override the fuel ratio limiter to deal with a tailgater…

So, if I understand:
1— move water fuel separator filter to the tank— easily viewed at every fuel fill and walk about;
2— bypass mechanical lift (60 psi) pump at HEUI pump with electric 60 psi pump between water separator and primary filters.

Essentially removing one pump and repacing geared galley pump with steady electric—

 

[Ronmar]

So, if I understand:
1— move water fuel separator filter to the tank— easily viewed at every fuel fill and walk about;
2— bypass mechanical lift (60 psi) pump at HEUI pump with electric 60 psi pump between water separator and primary filters.

Essentially removing one pump and repacing geared galley pump with steady electric—

Sort of. Remove separator primer all together, Install ford 60 PSI pump and filter module(has a filter and water/sediment drain on the bottom) from a 6.7l power-stroke, at tank to feed up to filter on engine.. connect fuel line from near tank pump up to input of filter on side of engine. Wire pump to ignition controlled power and enjoy your steady 60 PSI whenever the ignition is turned on

Would probably want to remove the piston assembly from the mechanical lift pump so it doesn’t burn up…

yep there are other pumps out there that would most likely be made to work, looks like Fass even makes pump and filter kits to upfit the 6.7 powerstroke, but you would have to play around with flow rate a bit to get something that matches up with the installed regulator to maintain the desired 60PSI at full load Or re-configure the pressure regulator. The fords are already in the ballpark designed to feed 60 PSI to a 6.7L engine… That and they are readily available And not horrifically expensive…

learned something new today, ford actually added a pressure switch to monitor primary feed pressure after ~2011. Have seen aftermarket pressure switch kits, but never a hint that a manufacturer finally did it If it drops below ~35PSI it throws a code… Low feed pressure kills unit injectors so it is to be avoided