Died w/decreasing idle

[bsorcs]

The '73 M35A2C has been distressingly idle the last few years...many more hours at rest than driving. I typically fire it up and run it for an hour or two on a weekly to bi-weekly basis. Occasional it gets to 3-4 weeks. Replaced the batteries w/in the last two years and have been running it farily regularly. Today it did not fire and run immediately as it typically does, but caught and ran as the batteries were running down. After the oil pressure came up I ran it for a half hour or so at ~1k, then ran it for another half hour at ~ 1.6k. When I pushed in the rev control, it gradually dropped down to ~700, then dropped to ~500 and stalled. It would not fire up after that.

It has been under cover the last year and a half. Last fuel fill was well over a year ago, and it's down to about a quarter tank. Tomorrow I'll add 10 fresh gallons with a bit of 2-cycle oil and a can of Seafoam and try 'er again. I am more than open to alternate suggestions for another approach, or for a different recipe. I likely will pick up a can of ether for luck, but I am not clear as to what prep I should do before trying to use it, or actually, how to use it.

I'll see if I have fuel filters, with the thought of changing those. Can't hurt. Time to delve into the TM again.

Bummed out.
bs

 

[98G]

Wet stack is probably an issue but probably not what caused this.

My guess says clogged fuel filters and life in your fuel system...

 

[fleetmech]

check to see if your in-tank lift pump is running

 

[bsorcs]

Wet stack is probably an issue but probably not what caused this.

My guess says clogged fuel filters and life in your fuel system...

I am inclined to agree re filters and life. Been trying to avoid wet stack with higher-rmp finishes. Thanks.

 

[bsorcs]

check to see if your in-tank lift pump is running

Decent call. I assumed it was running when it started initially. Thanks.

 

[Crf450x]

I’d just advise to skip the seafoam. It’s mostly alcohol. 2 stroke oil is always good to use though.

 

[98G]

I am inclined to agree re filters and life. Been trying to avoid wet stack with higher-rmp finishes. Thanks.

Wet stack isn't rpm dependent. It is load dependent. It can and will happen without a load even at high rpms.

Most common in underloaded generators, where rpm is constant.

 

[dmetalmiki]

These type of trucks have that symptom when the in tank fuel pump is CLOGGED, Or the spacers have dropped off the bottom of the in tank pump.
Or, The filters, especially the one first in line under the front of the truck which traps water.
It (the case), Fills with water and gunge and flow slows or stops,

After that, (Fix), It would point to the hydraulic head.

 

[fleetmech]

Wet stack isn't rpm dependent. It is load dependent. It can and will happen without a load even at high rpms.

Most common in underloaded generators, where rpm is constant.

Yup. Both of my Cat 3516 gen sets at work are very susceptible to that. Diesel's ain't happy running below 60% of their rated load for long periods of time. Get some heat in the water, then ramp the load up to 70 or 80% and leave it there, and you will have an engine that runs forever. Coolant temp is also a big factor, since a lot of diesels won't build full operating temp without some load on. Running under temperature reduces the engines efficiency and in more severe cases can cause incomplete combustion which leads to wet stacking. All that unburned fuel in the cylinders can also wash the oil off the walls.

 

[orren]

If all else fails check the high pressure pump located in the IP.
The seal slowly wears out and leaks more and more over time.
Consult the TM's.

 

[V8srfun]

I am lazy so I like to start with the easiest first. It doesn’t get easier than checking if the in tank is producing pressure. Just flip the power on and crack the bleeder on the top of the filters. Then I would go to replacing the filters. And depending on the results to where I would go from there.

 

[bsorcs]

I found external pump info in another thread and followed it up, but it seems better to stay in this thread since I started it. The following is a summary of where I am to date.

The Facet 41050 pump I hooked up has 3/8 npt fittings and it was easy to find compression fittings that enabled me to put it in line. Getting the tubing fit between the tank fitting and the pump took the most time. I mounted the pump to a piece of plywood with a strip of foam epoxied to the bottom. Took doghead's tack and used torpedo/banana plugs to connect to the existing line at the plug. Sounds great, no? All was fine until I found that there was no current to the plug. Clipped the pump to the batteries and ran it for ~5 minutes, watching the bleed screw above the filters...nothing,, and the pump didn't prime. Only thing I can think of is that the pump cannot lift the 15 or so inches from the tank, so I'll try pumping from a container thats higher. If that doesn't work I'll probably pull the in-tank pump out and see if it will run off of the batteries. Glad I have the NOCO charger in place.

Update 1: Tried to run the in-tank pump off of the batteries...positive to the pin on the left, negative to the right....silence. Didn't try swapping the pins. I will change the filters next, and see how they look. Tried pumping from a container of diesel that was higher than the fuel tank; the little pump would not prime, so I'll call Facet tomorrow; might try swapping the pins on the in-tank, then taking it out. Pressing on.

Update 2: Pulled the in-tank pump before starting on the filters. Looks pristine, but does not run when connected to 24v...assumed the larger pin is +, but chjoice of pins made no difference. Filters today.

Update 3: Flipped the console switch; listened to the alarm; measured 0.7 V at the plug for the in-tank pump. Large pin is the positive. Changed all of the filters; all were pristine and the housings were almost the same. I will re-try the Facet pump [those folks have not returned any of my calls] with filled tubing to see if that makes a difference. Each prior attempt it would lift the fuel only an inch or two from a fuel surface higher than the pump...what's up with that! running out of things to try. I'll also take out the in-tank again and peek into the tank at the pump access.
Q: I note that several folks have mounted a Carter pump P4603hd that looks like the one currently in the tank onto the in-tank frame. The Carter site says it is not submersible; has it worked for those who have installed it? If that one works and doesn't break the bank, I'll perhaps try it. I will call Pegasus Racing to see about returning the Facet. Frustrating and puzzling, especially the 0.7V.

 

[dmetalmiki]

Did you fix it>
Don't forget the Dreaded 'dropped off button fault' on the bottom of the Hydraulic head quill shaft.
That causes exactly the problem you have with your truck.
And it is an relatively easy fix.
There are many post with pictures and how too's in various forums and videos on the internet, As well as this site.

 

[bsorcs]

Did you fix it>
Don't forget the Dreaded 'dropped off button fault' on the bottom of the Hydraulic head quill shaft.
That causes exactly the problem you have with your truck.
And it is an relatively easy fix.
There are many post with pictures and how too's in various forums and videos on the internet, As well as this site.

I have yet to try the Facet pump with filled intake tubing. The thought of having to go into the hydraulic head is less than comforting, as my expertise is less than robust, shall we say, and my current physical setup is less than ideal for working under the hood. I'd really like to resolve the question about the low voltage observed at the in-tank plug. I'll take a look around re the button issue; I remember seeing reference to it years back when I was earlier in the deuce adventure. Thanks for the post.

 

[SCSG-G4]

A deuce will run without an in-tank pump, as long as there is no air in the lines going all the way to the injectors. One way to accomplish this is to 'pressurize' the tank with air. Several methods have been described in other threads, pick one.

 

[bsorcs]

A deuce will run without an in-tank pump, as long as there is no air in the lines going all the way to the injectors. One way to accomplish this is to 'pressurize' the tank with air. Several methods have been described in other threads, pick one.

Sarge,
I have been thinking about that, but I certainly would like to be able to figure out why I am not seeing 24 volts in the plug for the in-tank p;ump. I'm thinking about pressuring up the tank, but am uncertain as to how much pressure it will sustain. Hate to pop a leak!

 

[SCSG-G4]

Sarge,
I have been thinking about that, but I certainly would like to be able to figure out why I am not seeing 24 volts in the plug for the in-tank p;ump. I'm thinking about pressuring up the tank, but am uncertain as to how much pressure it will sustain. Hate to pop a leak!

2-3 psi will be fine, an adult male should be able to hold it down over the fuel opening with one hand.

 

[bsorcs]

2-3 psi will be fine, an adult male should be able to hold it down over the fuel opening with one hand.

Pulled the in-tank again; tank bottom is clean and relatively shiny; whitish crud starts about 6" up the sides. Got the Facet pump primed and pumping from a can of fuel and was able to bleed through the secondary filters; had significant return flow to the tank. Re-connected it to the in-tank pump fitting; this was a lot easier with the pump screws [8x32] loosened. Even though it is stated to have an internal check, and a 'lift min' of 36 ", the pump could not lift from the tank...it seems to need a prime. It might help if I filled the tank...currently about 10-12 gallons of clean fuel. In the interim, I'd be interested if anyone has any thought about the lack of 24v at the plug. I assume the issue has to be between the plug and the power switch in the cab.

 

[SCSG-G4]

Pulled the in-tank again; tank bottom is clean and relatively shiny; whitish crud starts about 6" up the sides. Got the Facet pump primed and pumping from a can of fuel and was able to bleed through the secondary filters; had significant return flow to the tank. Re-connected it to the in-tank pump fitting; this was a lot easier with the pump screws [8x32] loosened. Even though it is stated to have an internal check, and a 'lift min' of 36 ", the pump could not lift from the tank...it seems to need a prime. It might help if I filled the tank...currently about 10-12 gallons of clean fuel. In the interim, I'd be interested if anyone has any thought about the lack of 24v at the plug. I assume the issue has to be between the plug and the power switch in the cab.

Run the ground lead on the VOM back to the neg on the rear battery. You might have a bad ground. These trucks are famous for having bad grounds!

 

[bsorcs]

Thanks! Have never done anything electrical with the truck, save batteries stuff. I shall check that first thing tamale.

It's tamale. ~28v when hot in the plug is used with a ground to the batteries. Time to see if I can follow the ground. Might be expeditious to simply clip the ground and establish a new one on the frame someplace close. Still not certain that the in-tank pump is viable. Tried pumping with a length of tubing from the Facet pump suspended in the tank...no lift/joy. Another msg off to Facet.