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

[rustystud]

Read post #47 again. Yes there is a fuel leak.

 

[Bill Nutting]

I had this problem on my 934. It kept loos prime. I installed an electric fuel pump right at the tank to push fuel through the system. After I turned the pump on I found a line on the fuel pump with a hire-line crack. I replaced the plastic line with copper tubing… It now holds a prime for months. The electric fuel pump is a 24 volt unit used on generators. I removed this pump once I located the leak but left the fitting in place so I can easily re-install it again.

 

[Elk1111]

I would run a separate fuel line from a container of clean fuel directly to to injection pump so you eliminate the fuel system. If it starts up after running a bit then at least have narrowed it down to a leak somewhere between the tank and the injection pump.

 

[Floridianson]

Still waiting to hear OP check the rubber line that is the jumper from copper to IP booster. That's where I am leaning since the OP said in tank rubber was replaced along with fuel line and filter canister checked.

 

[rustystud]

I don't know why he just doesn't pressurize the fuel lines and find the leak or leaks that way. You will see and hear the fuel line leaking that way. Easy Peesy. Otherwise he could spend hours looking all over for that stupid leak.

 

[Floridianson]

Just to be clear I never said not to try and pressurize the suction side of the IP booster pump. Yea OP could drop the rubber line off the IP booster and drop off suction line on top of fuel tank and see if there is a leak. What I have found with a system that has 70 psi pressure of fluid will show up as a fluid leak if there was a hole not take on air and OP said his system makes 70 psi. Thats why I say check everything on suction side.

 

[7Dust]

Just received NOS injector.

I also got a NOS secondary filter assembly just so I could get another pressure regulator spring since I lost the old one.


The NOS injector also will not pop until I add starting fluid. So will consider injectors not the problem.

When I was putting new spring in my old canister assembly, I noticed a small piece of crud under the cup? That the spring seats on. I cleaned out the crud but still - no starting fluid, no start.

I am thinking that maybe there is more crud in the secondary filter mounting assembly. I have a new one - maybe just swap it out.

After all, most of my no starting fluid, no start problems started shortly after changing all my filters in the first place.

OR - I start it with starting fluid. Every time. It’s just what I might hafta do now.

Will see!

 

[ToddJK]

I would keep running transmission fluid in the fuel for a while, maybe after some time it will help breakdown and clear whatever crud is causing issues.

 

[7Dust]

I would keep running transmission fluid in the fuel for a while, maybe after some time it will help breakdown and clear whatever crud is causing issues.

Turns out the single piece of crud I was just a small piece of black foam that broke off of the secondary filter and was floating around.

Other than that, the canisters look clean I’m going to change the secondary and final filters anyway since I’m in there - but they don’t appear to be the problem.

 

[7Dust]

Question:

Will turning up the fuel increase the fuel pressure while cranking?

 

[williamh]

Question:

Will turning up the fuel increase the fuel pressure while cranking?

No it will not. Only increase amount of fuel delivered. Not pressure

 

[ToddJK]

Any updates to a solution?

 

[7Dust]

Any updates to a solution?

.

No Solution.

Have checked for leaks all the way from the lift pump to the tank return.

I have noticed that the pressure while cranking is ~5PSI only.

Should the booster pump start making pressure while cranking?

Once I squirt the truck, it fires and builds to 40 PSI in a few seconds.

 

[7Dust]

One more thing.

I just noticed that when I turn on the fuel, I can see fuel flowing from from the booster pump through the small forward facing plastic line towards the flame heater.

If I kill the fuel, I can see the line fill immediately with air.

I do not think this is normal?

Should I just put a plug in that line?

Is this blown seals in the booster?

OR?

 

[ToddJK]

I don't remember seeing air like that in the line from the flame heater and it's possible that may be the source of the issue. I suggest deleting the flame heater altogether, that's why my truck got nicknamed crispy, because the fuel line touched the intake and melted, dumping fuel on the exhaust starting one heck of a fire. Luckily I saved it, but Rattling trucks.com has a delete kit that is well worth it and it looks nice too. The return line which is clear can be deleted by just removing it from the flame heater and then a new line where it connects between the injectors. The other line comes off from the bottom of the IP and is not easy to get too but doable with patience.
I doubt it's blown seals, usually if those fail the truck won't run at all or very hard to get running and won't run well when it is.
I'd remove the clear line and put a new line in where that T is on the injector return lines. The other line from the IP if you can't get it off and a plug for the IP, you can cut it, plug it with a screw and some fuel resistant sealant.

 

[7Dust]

Plugged up the flame heater feed at the booster pump.

No difference.

I'm thinking the booster pump has to come off. Ive had it off before but that was when I replaced the injection pump years ago.
No way do I want to do go through that again if I don't have to!

Maybe I can put the engine on a jack, , unbolt from the front mounts, and rasise the nose of the engine until the booster pump clears the steering box?

Cannot figure out why the pressure does not buld while cranking. :/

I am out of ideas.

 

[williamh]

Have you pulled the ip head to make sure the button is still attached ? It migh be loose and only staying attached when the rpm’s get up there. I hated pulling that whole assembly off because it wouldn’t start. Turned ou it was the ip head button off and the piston wouldn’t drop all the way down.

 

[Floridianson]

I do not believe his plunger timing button and clip has fallen off because he said it run fine after getting it started.
The IP booster has a bypass built in and if it is open / leaking it puts the fuel from the booster back into the fuel inlet of the booster. Do not know if this could cause a problem on hard starting. I will look for the thread where the OP had problems with the bypass but thinking his problem was performance. Yea real pain to get to the booster. Are you getting some flow / pressure at the fuel tank with the return line off the tank and in tank running?

 

[williamh]

I’m just trying to throw some ideas out there. I’ve had trucks sit for months and start with a little extended cranking but fired up. Anything over 600 rpm should fire up. And I can’t see the injection system draining back into the tank , the filter shells should hold quite enough fuel to get it started after sitting , I just can’t see it siphoning the fuel out.

 

[Floridianson]

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.