Will start only with a squirt of starting fluid. Runs great once started.

[7Dust]

Again, once truck is running, fuel pressure is great, truck runs and drives fine.

When i turn on the lift pump, I can hear fuel running back into the tank.

Low pressure at hydraulic head inlet UNLESS I pull the line and put my finger on it, then I get ~40psi while cranking.

 

[Floridianson]

Although the booster pump can produce as much as 70 80 psi it's that overflow valve on the other side of the head that maintains the pressure the pump can put out. I tried to describe it once like a garden hose without any nozzle on the end you turn it on and there's a big stream coming out but it's not like high pressure just a lot of volume. You put some kind of attachment on the end of the hose and create head pressure it comes out in a stream and shoots out 20-30 ft. The overflow valve has an orifice in it and it only allows so much fuel to come out I think it was rated at like 5 PSI on the other side of the overflow valve. Does that make sense?

 

[Floridianson]

Well I thought I mentioned it earlier. To check that delivery valve that black 12 point cap on the side of the head. Just don't lose that little spring so take the cap off real careful. I did a post about it on the board showing a picture of that delivery valve that it has a screwdriver slot in it so you can twist it if it's stuck in there. I mean I'm just guessing here it really shouldn't run if it's stuck closed or stuck open but maybe it's just a little sticky and when you get it fired up the higher fuel pressure opens it. One more time don't lose the little spring or the delivery valve if it pops out.

 

[7Dust]

Yeah I'm starting to think its the overflow on the canister assembly that is my problem. I just cannot seem to get a base fuel pressure of 5 PSI with only the lift pump - and I bought a NOS lift pump just to make SURE it wasn't the pump.

I have checked the overflow on the filter canister multiple times and cannot see any crud in there.

I have pulled the overflow on the hydraulic head (forward of HH) and cleaned it too.

When I turn on the pump I cane hear the fuel retutning to tank - but only getting base fuel pressure of 2PSI maybe? But that could be my crappy amazon gauge.. .

Funny thing now though, the truck still needs a squirt to start.
However, once it has run - I can immediately get it to (struggle to) start if I floor the pedal without starting fluid.

Something is clogged up since I deep cleaned the tank and filters. This truck used to be impossible NOT to start - it would fire off with the slightest blip of the starter.

I think Floridianson is right here is an overflow stuck open somewhere not allowing pressure to build. There is one at the booster, one at the secondary canisters, and one on the hydraulic head - haven't seen the problem yet.

 

[smoke]

Maybe replace the springs in all three overflows. Over the years springs do wear out and lose tension pressure. You aren't going to see it but they do.

 

[DaneGer21]

Maybe the HH itself is getting tired…

 

[Floridianson]

On the secondary fuel canister there is the over pressure valve. On the Head there is the over flow valve and the booster on the IP is the bypass valve. The bypass on the booster opens when there is an over pressure in the booster pump and it just reroute the fuel back to the booster pump inlet.
Thought we talked about removing the fuel line off the T fitting at the secondary that comes from the overflow valve on the head. Then place the line in a jug and see if you have good flow with just the in tank pump running? Good running truck it does not take a lot of pressure just flow through the Head for it to start.

 

[7Dust]

Fuel Pump Facts:
I am seeing ~2 PSI on a gauge at the tank pump.
It is a NEW , just purchased NOS pump. Zero miles.
I have 24 volts at the pump static, 28 when running.

Secondary Canister Assembly Facts:
The secondary canister assembly is NEW (NOS) - with new bypass.
The bypass at the canister is not leaking. with engine off.
I am seeing ~0 PSI at the gauge.
Seems to be lots of flow - but no real pressure by the gauge.

Booster Pump Bypass Fact:
The bypass at the booster pump to the flame heater is now blocked with a plug.
No fuel can escape and return to tank.

Hydraulic Head Bypass Facts:
This is the only place where fuel is returning to tank.
By design, the bypass has a hole (assuming to bleed air) so some fuel returns to tank here.
If I block the bypass - no fuel returns to tank, but fuel base pressure does not rise.

If I Spray the Truck - Facts:
Trucks will crank and crank until the starting fluid is picked up and truck starts to fire.
Booster pump raises pressure from at secondary canisters from Zerto ~50PSI
Gauge at tank stull shows ~2 PSI
Runs fine.

My Brain Says:
What now?
Syetem seems properly sealed and not leaking back to tank (except for small HH bypass) and not leaking externally.
Seems like I should have a high base pressure and but I do not.
Looking for next idea because I have none.
Except blow acetone back though all the lines? Seems like a waste of time and acetone.
Even if there was an obstruction in the fuel lines (I do not think this is the case) seems like the pressure would be higher at the tank because of the blockage???


HAPPY HOLIDAYS!!!!!!!

 

[cattlerepairman]

@7Dust for what it is worth, my in-tank pump cranks out about 7-9 psi. Not that it would make much of a difference, as long as it moves fuel.

 

[7Dust]

@7Dust for what it is worth, my in-tank pump cranks out about 7-9 psi. Not that it would make much of a difference, as long as it moves fuel.

^^^ Correct! I aint seeing that.
My old Parker pump did ~2PSI.

SO bought NOS pump and assembly.
STILL ~2PSI at the tank and maybe .5 PSI at the secondary filters.

No, Not the soft lines in the tank - Ive checked, replaced on old pump and the new one.

SO - the fuel isn't leaking outside the fuel system.
All three fuel bypass (at booster, at secondary canisters, and at HH) have been disabled, replaced, or cleaned.

All this started after a deep tank clean and fuel filter swap.

Ive disassembled and inspected nearly everything.
1. Deep Cleaned Tank
2. Replaced all of the injector hard lines with NOS lines.
3. Deep cleaned original fuel pump and replaced hose
3. NOS fuel pump and replaced hose
4. New primary and seconday filters - TWICE!
5. Replaced hard line at tank through frame rail that had slight kink
6. Checked the narrow orifice at primary filter
7. Disabled bypass at the booster pump to flame heater
8. Cleaned original bypass at canister filters THEN replaced with NOS canister assembly and NOS bypass
9. Cleaned bypass at HH (this is the only one that flows back to tank through very small holewith pump on - but looks like it is supposed to be there to purge air)
10. Purchased NOS injector to check and see it it would pop off with cranking only. NOPE.
11. Lots more stuff that I can't remember right now.

Next?
MAYYYYBE there could be crud in the lines somewhere but I doubt it.
If there is blockage in the lines, seems I'd see high pressure at the tank gauge?

MAYYYBE the HH is crudded up?
Should fuel flow through it and out the HH bypass with just the tank pump on?
OR should the bypass on HH only activate with engine cranking?
Ive blocked the HH bypass for testing and it still doesn't raise my base fuel pressure.

 

[ToddJK]

Perhaps it's not a fuel delivery or fuel pressure problem, if fuel pressure can pop off the injectors for it to run, it should start, in theory, but have you pulled the injectors to check the spray patterns? I ask this, because the deuce will start with a non working in tank pump, the IP and HH will pull the fuel and provide all what's needed. Another test I would do is a compression test, cracked cylinder heads or badly worn rings/sleeves can lead to poor compression which results in hard to non starting engines. When it is running, does it roll coal bad or is it fairly clean or does it burn a lot of white smoke? Any blowby from the slobber tube or from the oil fill cap on the valve cover? I would assume that if the injectors had a good spray, meaning it shoots a nice mist and no streams or lack thereof, compression test proves good on all cylinders, then I would look into the IP. The HH may need to changed or rebuilt with new seals or the IP is getting worn out. If this truck has lots of idling time or miles on it with just standard low sulfur diesel fuel,I wouldn't doubt it if the IP/HH suffered because of it since today's low sulfur diesel does not lubricate like it used too when it had more sulfur back when these trucks were built. I think that also contributes to a lot of HH heads locking up when sitting for a long time, Tactical Repair even had a video questioning the same thing. You could try running it with some oil or transmission fluid (gallon or more) and see if that helps, it's possible parts can be sticking as the truck did start and run no problem before in the past, but it may take some time running with cleaners like trans fluid and a good amount of it to fix sticky parts in the IP/HH, but it's worth a try if nothing else raises red flags. It's just my two cents, but I would try running 5-10 gallons of trans fluid through the system and run it hard to see if anything improves before buying parts or tearing into it.

 

[7Dust]

Perhaps it's not a fuel delivery or fuel pressure problem, if fuel pressure can pop off the injectors for it to run, it should start, in theory, but have you pulled the injectors to check the spray patterns? I ask this, because the deuce will start with a non working in tank pump, the IP and HH will pull the fuel and provide all what's needed. Another test I would do is a compression test, cracked cylinder heads or badly worn rings/sleeves can lead to poor compression which results in hard to non starting engines. When it is running, does it roll coal bad or is it fairly clean or does it burn a lot of white smoke? Any blowby from the slobber tube or from the oil fill cap on the valve cover? I would assume that if the injectors had a good spray, meaning it shoots a nice mist and no streams or lack thereof, compression test proves good on all cylinders, then I would look into the IP. The HH may need to changed or rebuilt with new seals or the IP is getting worn out. If this truck has lots of idling time or miles on it with just standard low sulfur diesel fuel,I wouldn't doubt it if the IP/HH suffered because of it since today's low sulfur diesel does not lubricate like it used too when it had more sulfur back when these trucks were built. I think that also contributes to a lot of HH heads locking up when sitting for a long time, Tactical Repair even had a video questioning the same thing. You could try running it with some oil or transmission fluid (gallon or more) and see if that helps, it's possible parts can be sticking as the truck did start and run no problem before in the past, but it may take some time running with cleaners like trans fluid and a good amount of it to fix sticky parts in the IP/HH, but it's worth a try if nothing else raises red flags. It's just my two cents, but I would try running 5-10 gallons of trans fluid through the system and run it hard to see if anything improves before buying parts or tearing into it.

^^^ It ran and started absolutely PERFECT before sitting 5 years with limited starts.

After cleaning the tank and replacing the filters, it won’t start without starting fluid now.

Before pulling the tank, a quick press of the starter would fire the truck off. It was almost impossible to touch the starter and it not start!

Now, once it starts, it runs great, no smoke, drive it around the block with good power. Kill it, and it won’t start without fluid again.

Ive burned 5 gallons of fresh fuel and two bottles sludge be gone but it still won’t start without starting fluid.

Something is probably sticking but damn if I can find it.

 

[7Dust]

^^^ It ran and started absolutely PERFECT before sitting 5 years with limited starts.

After cleaning the tank and replacing the filters, it won’t start without starting fluid now.

Before pulling the tank, a quick press of the starter would fire the truck off. It was almost impossible to touch the starter and it not start!

Now, once it starts, it runs great, no smoke, drive it around the block with good power. Kill it, and it won’t start without fluid again.

Ive burned 5 gallons of fresh fuel and two bottles sludge be gone but it still won’t start without starting fluid.

Something is probably sticking but damn if I can find it.

I have pulled the injectors and checked the pattern. They will not pop until I spray it with starting fluid.

I also tried with a NOS injector and same result.

 

[ToddJK]

I have pulled the injectors and checked the pattern. They will not pop until I spray it with starting fluid.

I also tried with a NOS injector and same result.

If none of the injectors are popping while cranking, then I would look into testing those injectors to see if they pop off around the correct psi. Quite a few guys here have some good threads on how they built their own rig to test them, or send them to someone who can. If the injectors prove to be good, then I suspect your IP. Have you removed the shutoff cover and made sure everything moves freely? If so, you're IP may need to be rebuilt or swapped out, but I wouldn't doubt there's some sludge in there preventing it from working properly. If you don't want too or unable to rebuild the IP, contact Clint from C&C equipment and see if he's willing to or offer some additional help, I know he's located in Indiana, but the man is very good with these trucks.

 

[Floridianson]

This is tread is getting pretty long and you still haven't found the problem. Without reading through the whole threat again did you happen to check that delivery valve on the side of the head?

 

[7Dust]

If none of the injectors are popping while cranking, then I would look into testing those injectors to see if they pop off around the correct psi. Quite a few guys here have some good threads on how they built their own rig to test them, or send them to someone who can. If the injectors prove to be good, then I suspect your IP. Have you removed the shutoff cover and made sure everything moves freely? If so, you're IP may need to be rebuilt or swapped out, but I wouldn't doubt there's some sludge in there preventing it from working properly. If you don't want too or unable to rebuild the IP, contact Clint from C&C equipment and see if he's willing to or offer some additional help, I know he's located in Indiana, but the man is very good with these trucks.

I replaced with NOS injector and re-tested. Still will not build pressure and pop without starting fluid.

then, runs fine.

 

[7Dust]

This is tread is getting pretty long and you still haven't found the problem. Without reading through the whole threat again did you happen to check that delivery valve on the side of the head?

On the side of the HH? It has also has return from injector and return to tank?

it Is clean and apparently functioning properly. Soaked in acetone overnight and verified crud free.

There is a pinhole inside this one which apparently is by design to bleed air back to the tank?

I have even blocked this return in testing to see if will raise the base fuel pressure from lift pump only. Even with this return blocked and no longer bypassing fuel to the tank, there is no change to the base fuel pressure.

 

[NY Tom]

I replaced with NOS injector and re-tested. Still will not build pressure and pop without starting fluid.

then, runs fine.

Have you taken off the Hydraulic Head and inspected it?
The Hydraulic head is what builds the pressure to fire the injectors. It is a finely lapped piston which pressurizes and pumps the fuel into the injector lines. Some say that the piston can get worn or develop pickup (galling) from bad fuel, dirt, water, or even newer fuels. To me it is very strange that the engine will run after starting with ether. This pump would have to build enough pressure to pop the injectors at some point in that case.

If the hydraulic head cannot pop the injectors when the motor is turning by the starter something is wrong with it. New ones can be had. But perhaps you can take yours apart and look at the piston. Let us know how it fits and what it looks like. Should be a real nice fit in the bore.

 

[Floridianson]

The delivery valve is that 12-point cap on the side of the head facing the firewall. Underneath there is a small spring and the delivery valve. It's kind of like a needle in seat. It can be removed and cleaned and the seat also cleaned.

 

[7Dust]

The delivery valve is that 12-point cap on the side of the head facing the firewall. Underneath there is a small spring and the delivery valve. It's kind of like a needle in seat. It can be removed and cleaned and the seat also cleaned.

The little doo-dad on the HH that points towards the drivers door?

Is it just held in with 12 point socket?