4BT hard start issue revisited
 

I have made a topic a few months ago about my 4BT not starting right. I have to crank it a lot before it starts. At first it doesn't even smoke. It does this regardless if it has been sitting for 5 days or for 5 minutes, regardless if it's warm or cold or if I primed the lift pump in before trying to start it.
Once it starts it runs just fine.

The biggest update is that I measured the fuel pressure and it's at around 10 psi, same for cranking / running.

Here is a clip of it starting. It ran for 15 minutes then was stopped for 5 minutes before the clip.

The buzzer is a low-oil pressure warning.

Is the lift pump the culprit since it only makes 10 psi ?

EDIT: I forgot to mention that I have check valves on both the fuel feed line so nothing goes back to the tank after I stop the engine.

It sort of sounds like it is cranking too slow. Have you checked the condition of the batteries and cable connections? It could also be a worn starter. The 6bt in our dodge starts instantly but it turns a lot faster than yours seems to be. if it has a bosch ve injector pump it wouldn't matter if it had no fuel pressure at all since they have a vane pump built inside but I don't know what pump you have.

I agree with gradyc on this...............also check yer starter contacts, I bet they are very thin, if so go to fostertruck.com and get some new ones

Starter was checked 200 hrs ago and we've replaces the bushings, electrical system is perfect (following a rebuild after it caught fire - all big stuff done in 1/0 gauge). I will go over the connections again.

In the clip I was running two batteries. But it's unusual since it does it even after running for hours. I stop it for 10 minutes and it starts bad.

Also, this behavior started pretty much randomly and it was gradual. One time I struggled for 30 minutes to start it with no luck and it was cranking way faster than in the clip. Zero smoke, ended up bleeding the injector lines and it still wouldn't start.

Shouldn't it smoke from the first cranks ?

The pump is Bosch, could be a VE, I'll post some pics later.

Injectors already checked? Spray pattern, release pressure, rattle?
Maybe you need some shims to regain the correct opening pressure?
It's turning very slow.

Injectors and starter are coming off today. To my shame I never checked the injectors although it was in plan for quite some time :(

Maybe the guy who made the starter bushings used bad material and they are worn again.

We had one injector hang open on the old dodge and the compression pushed air backwards into the IP causing and airlock and kept it from starting.

Ok, injectors are off, visually everything is ok, a tiny bit of carbon deposits on the tip. They are going tomorrow to a Bosch service for checking.

What is the injector opening pressure ? It's a 1991 engine, Bosch VE pump (without AFC if that matters) .
I've been reading that the injector opening pressure is 245 bar for first gens with the VE. Is that correct ?

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According to the Case service manual, the injectors should open at 245-253 bar. They are Lucas injectors. 0.30mm diameter nozzles.

The results of the test: all injectors open at 210 bar and the spray pattern is bad. I was also told that they can't adjust them. I'm going to another shop, which I've used in the past, for a double check and maybe they can adjust them and check the pattern at the right pressure.

So far so bad, if they still spray bad at 245, I'll have to get new nozzles or new injectors. And these being Lucas I'll probably go for some complete Bosch injectors :argh:

Good Adrian- double check is cheap, but important due to measuring instrument variances.

Welcome in the world of injectors, my friend!:c:

The second place I took them said the spray pattern was right but the pressure opening pressure is 210 bar. What's weird is that they all open at 210...
So I installed the injectors on the lines and cranked the engine to see the spray pattern, which is perfect. At least I don't have to spend $$ on nozzles.

Now, the suspicion is some valve in the IP according to the second shop which checked the injectors. If tomorrow morning the engine will crank more than a couple times before the injectors spray something it's that valve and I will have to take the pump off and take it in for checking. If the injectors spray on the first go, I will take them to get adjusted. At least that's what my logic tells me.

Update:
After sitting for the whole Saturday, all injectors sprayed perfectly on the first crank. So the pump holds pressure.

I'm going to get the starter off tomorrow and adjust all injectors to the right pressure. Hopefully that fixes it or I find serious wear in the starter.

Ended up going to a third place to adjust the injectors and I got a second opinion that the nozzles are bad. Second injector shop tried to take me for a ride and blamed bad compression and a bad pump. Maybe they would have liked to have me get the backhoe in, check the compression, take the IP off and check it and then conclude that they don't know what's wrong. I sure hope this third place doesn't want to take me for a ride blaming the spray pattern...
/rant

So, I believe I need nozzles. The main problem is that the injector and nozzle are CAV and I've been told that Bosch nozzles don't fit. It's a 7mm nozzle, 4 hole, 0.0118" orifices. Does anyone know for sure if the Bosch nozzles fit in CAV injectors ? Who sells stock nozzles ?

In the clip I was running two batteries. But it's unusual since it does it even after running for hours. I stop it for 10 minutes and it starts bad.

Also, this behavior started pretty much randomly and it was gradual. One time I struggled for 30 minutes to start it with no luck and it was cranking way faster than in the clip. Zero smoke, ended up bleeding the injector lines and it still wouldn't start.

Shouldn't it smoke from the first cranks ?

Yes, you should be getting smoke; no smoke=no fuel. make sure the pump itself is well bled out. Maybe even supply it from a different source to verify your not getting air from somewhere in the supply side.

Tried both bleeding the lines and starting it from a bottle. Still no go and the conclusion is bad nozzles.

Does anyone have some bad Bosch nozzles for a first gen ? One would be great, so I can check if they fit in the injector bodies I currently have...