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

[7Dust]

On a good working system the in tank pump will circulate fuel through the entire system and back to the fuel tank before you hit the starter. The thing is throwing me off is he said he's having some high running pressures almost 80 psi. On a good running system and the whole system primed we really don't need the in tank pump running just helps us if we change the fuel filters to get the air out and then circulate the fuel back to the tank. I'm just trying to find out if he has fuel circulation to start with. We started off thinking it was air but once the system's running it should have primed up the whole system I've been able to start without starting fluid.

Best indication is that the booster pump isn’t raising pressure high enough to fire with starter cranking.

A little starting fluid gooses the cranking speed high enough to start.

Unfortunately, the booster pump is inaccessible to service in the truck best I can tell.

 

[NY Tom]

Best indication is that the booster pump isn’t raising pressure high enough to fire with starter cranking.

A little starting fluid gooses the cranking speed high enough to start.

Unfortunately, the booster pump is inaccessible to service in the truck best I can tell.

Search around on the site here. It can be done in the truck. You need to loosen up some motor mounts and then you can shift the engine over to one side if I remember correctly.

 

[Elk1111]

I’m sure you have already checked this but how dirty is your air filter?

 

[Floridianson]

Best indication is that the booster pump isn’t raising pressure high enough to fire with starter cranking.

A little starting fluid gooses the cranking speed high enough to start.

Unfortunately, the booster pump is inaccessible to service in the truck best I can tell.

You can put a 0 to 20 psi gauge on the bleeder screw and try cranking the engine over and see what kind of pressure you're developing.

 

[7Dust]

Air filter is new.

Before sitting, it was almost impossible to crank the engine and it not start. Less than a second it would fire off.

I’m almost thinking checking the hydraulic head would be easier than the booster pump.

Maybe it has some varnish in it keeping it from articulating properly?

 

[ToddJK]

Air filter is new.

Before sitting, it was almost impossible to crank the engine and it not start. Less than a second it would fire off.

I’m almost thinking checking the hydraulic head would be easier than the booster pump.

Maybe it has some varnish in it keeping it from articulating properly?

When you changed the filters and stuff, did it look like there was any algae in there or in the tank? A small amount of that stuff can wreak havoc in the fuel system as it will get into everything.

 

[Floridianson]

Have you even checked the fuel control unit assembly? It should work freely and be in the 7:00 position. With your finger you should be able to push it towards the firewall and let it go and it snap back to 7:00.

 

[7Dust]

When you changed the filters and stuff, did it look like there was any algae in there or in the tank? A small amount of that stuff can wreak havoc in the fuel system as it will get into everything.

Oh yeah. Worst infestation ever.

that’s the thing. Whatever happened, happened as I changed filters and cleaned the tank.

 

[7Dust]

Have you even checked the fuel control unit assembly? It should work freely and be in the 7:00 position. With your finger you should be able to push it towards the firewall and let it go and it snap back to 7:00.

yep. It’s fine.

 

[NY Tom]

Air filter is new.

Before sitting, it was almost impossible to crank the engine and it not start. Less than a second it would fire off.

I’m almost thinking checking the hydraulic head would be easier than the booster pump.

Maybe it has some varnish in it keeping it from articulating properly?

Yes it should be easier to take off the hydraulic head than the booster pump. Order a new set of O-Rings while you are in there to change. Also you might want to get your hands on a spare clip as they sometimes break a leg.

If it does not make any difference than you can attack the booster. At this point you have narrowed things down a lot.

Just note - if your in-tank pump is not flowing right it won't start after the hydraulic head job. I had mine off to change O-rings and just my luck after it was all back together it would not start without fluid. And it would not run. No fuel at the injectors. Turns out the lift pump wire connection had somehow gotten loose or corroded and I had not noticed. Fixed that, let the pump run for 30 minutes and the truck fired right up and ran. Never had a problem again.

It will not prime without the lift pump apparently. Even after extended cranking.

Would love to see you get this resolved.

 

[Floridianson]

Myself I would hold off on removing the hydraulic head as the op says once he gets it started it will run. I sent a PM telling him to remove the cap and not to lose the spring and check the delivery valve. Also he can remove the cap and check the overflow valve is not all gummed up. Same thing on the overflow valve don't lose the spring. A gummed up overflow valve could create that high pressure that he says he has. All these things can be done without removing the head. Just a side note on that overflow valve if that was plugged up that would cause high pressure but also wouldn't allow any circulation until the booster pump started producing high enough pressure to open that valve.

 

[ToddJK]

Oh yeah. Worst infestation ever.

that’s the thing. Whatever happened, happened as I changed filters and cleaned the tank.

Have you treated it with anything for the algae? That stuff will line your fuel lines and everything. That is probably what is causing the pressure issues as you said it started great and then over time it would take longer eventually leading to using starter fluid. I wouldn't be surprised if that stuff made it past the filters and into the HH.

 

[Mullaney]

Have you treated it with anything for the algae? That stuff will line your fuel lines and everything. That is probably what is causing the pressure issues as you said it started great and then over time it would take longer eventually leading to using starter fluid. I wouldn't be surprised if that stuff made it past the filters and into the HH.

.
Might even be worth getting a small electric pump and a filter housing to let the fuel circulate with the truck turned off and just sitting in the driveway. Run it supervised for a while to make sure nothing stupid happens... One hose on the bottom of the tank and the other just pouring it back in at the top. Trying to pull from the left and right sides of the tank.

Several days "polishing the fuel" could help your problem. And you could let it run through the lines on the engine after you have gotten the tank fuel as clean as you can.

 

[7Dust]

Myself I would hold off on removing the hydraulic head as the op says once he gets it started it will run. I sent a PM telling him to remove the cap and not to lose the spring and check the delivery valve. Also he can remove the cap and check the overflow valve is not all gummed up. Same thing on the overflow valve don't lose the spring. A gummed up overflow valve could create that high pressure that he says he has. All these things can be done without removing the head. Just a side note on that overflow valve if that was plugged up that would cause high pressure but also wouldn't allow any circulation until the booster pump started producing high enough pressure to open that valve.

I checked the cap and spring on the secondary filter. Lost the spring! Replaced with new one. Then I found the old spring so now I have spare.

I deleted the flame feed at the booster pump. Found out there was another cap and spring pressure regulator at the booster pump. So while I was there I checked and cleaned the cap and spring at the booster pump.

everything seems clean but of course I haven’t pulled the booster due to it’s inaccessibility. I’m wondering if the hydraulic head has a partially detached clip on the button? Maybe?

 

[7Dust]

Have you treated it with anything for the algae? That stuff will line your fuel lines and everything. That is probably what is causing the pressure issues as you said it started great and then over time it would take longer eventually leading to using starter fluid. I wouldn't be surprised if that stuff made it past the filters and into the HH.

I cleaned the hell outta it. Gallons of acetone, degreaser. boiling water, pressure washer with sewer attachment to past the tank baffles.

Cleaned the pump with acetone.

All new fuel, all new filters

Added two quarts of sludge be gone. If it treats 1000 gallons a quart, it should work even better for 10 gallons!

Biocide added.

Acetone added anywhere I see a spec of crud.

 

[NY Tom]

I hate taking things apart for no reason...but once you know...you know.
You already have been through most of the fuel system leading to the Booster pump and HH it sounds like.
Yes Floridianson has a damn good point that the engine will stay running after start-up. To me this is odd.
So what more can you do?
Pull apart the HH in the name of changing your O-rings and learn all about it while you do it?
Still no good I suppose you can work on the booster pump for the same reason - all with O-rings that can lead to fuel in the oil when they go bad.
What else? IDK maybe check compression? I know my motor is tired but it starts up pretty quickly with just a slight press on the pedal unless it is really cold. Even then no more than 5 or 6 seconds of cranking would be required.
Valve adjustment needed?
Trying to think of reasons why it would not start but will run... I would normally expect to find the opposite problem if using starting fluid...having a problem with the fuel supply. But if the engine keeps running that is not the case. Will it run under load or does it starve for fuel?

 

[smoke]

This may sound stupid but I'm going to say it anyway. How good are your batteries and starter? The reason I say this is because if the starter isn't spinning engine over fast enough it makes a different in pressure building. Newer engine if they don't crank fast enough, they usely have trouble starting because ecm doesn't see right rpm to fire injector or coil. I know this is mechanical engine but a loss in rpm cranking means loss of pressure building. Let's say the starter normally spins the engine over at 250 rpms and builds 60 psi fuel pressure. Now batteries are little weak or starter dragging some. It now spins at 200 rpms and only builds 50 psi fuel pressure. But with a little shot of ether, it will fire off the engine because ether sped up the engine when it fired off cylinders pushing it to the 250 rpm and reaching the 60 psi mark. I would check to make sure you're spinning the engine over fast enough per TM.
I work on newer cummins. One of the little tricks we do if the engine runs great but is getting a little tired and the idle oil psi starts to fall off. Is we go in ecm and bump the idle up by 25-50 rpms which in turn bumps the oil psi back up by 5-10 psi. The oil pump gears are half the teeth of crank so 2 to 1 ratio. So, 50 rpms on crank makes oil pump spin 100rpm faster producing more pressure.

 

[7Dust]

Have been starting (barely) with starter fluid and driving truck as normal.
Bad thing is, if truck runs down batteries just a tiny bit - it aint startin.

Have some new data for all of you to consider though and figure out why truck is soooo hard tio start:

My fuel pressure gauge is on secondary filter and is super low.
HOWEVER, if I pull the line going from secondary filter to hydraulic head and put my finger on the end, I can get 40 PSI or more on the gauge.
This leads me to believe that the problem is NOT the lift pump (it is new), and is NOT the booster pump (however it shows no pressure while crankinbg unless the hydraulic head line is blocked).

What could be the problem in the hydraulic head bleeding off all my pressure?
I am thinking about blocking the return on the hydraulic head and seeing if I can force it to build pressure?

The fuel is going somwhere - I have lots of FLOW but not much pressure until engine fires off and is running (after starting fluid squirt).
I am thinking the only place it could go is through the hydraulic head return.

ALSO - the pump is not leaking internally to oil. There is not fuel in the crank case.

 

[foxtrot]

Your truck idles and runs smoothly with good throttle response.
Perform pressure tests at required RPMs.
Do you have any high power?

 

[DaneGer21]

How is your flow back to the tank via the return line?