Hard start - 4BT Cummins - Lull 644B - Injection pump?

[Andy1845c]

Hey guys, wanna pick some brains on this-

I bought an older (early 2000's) Lull 644B that was a project someone gave up on. Story I got was the transmission stopped shifting, it sat and got algae in the fuel and plugged the injectors. Allegedly someone before me installed new injectors.

When I got it, it would start with either and run decent - although had a touch more white smoke that I would call normal - but even when warm the engine would not restart without either. It don't really even get much white smoke when cranking.

I pulled the injectors and did a pop test and found that they all popped at 4000 PSI. Searching the internet I see they should be set to 3500 PSI. Pulled them apart and removed the smallest shim and got all of them popping somewhere close to 3500. Reinstalled and it will restart when warm but still have to crank excessively. Sometimes it will run the battery down and not fire. Other times its start almost normal.

Still not getting a lot of smoke when cranking. Usually getting a belch of black when it finally fires.

Compression test was 400 on 3 cylinders and about 325 on 1. Sounds ok when it is running. Throttles up and idles down

I've messed with the fuel cut off. Wired it fully back.

Doesn't look like the pump has ever been off which makes me think the timing hasn't been messed with.

I am leaning toward pulling the pump and sending it off to a pump shop at this point. If there was crap in the fuel maybe it damaged the pump and I am not getting consistent pop off until the engine spins fast enough?

Anything else anyone would try first?

 

[Andy1845c]

Just an update - I called a pump shop and they thought it seemed reasonable the next step would be to send them the pump and injectors and they would take a look.

I'll post back what they find.

 

[thepumpguysc]

U shoulda checked supply TO the injection pump first before pulling it..AND the pressure of the overflow valve..
Oh well, live and learn..

 

[Andy1845c]

I haven't pulled it yet. Wanted to do it tonight but ended up working late.

The lift pump appears to be new. I have tried pumping the primer while cranking. Plenty if fuel coming out the return when I do that but no improvement in starting.

Whats the proper way to test this? Where is the overflow valve and how can I check that? I can do that tomorrow before pulling it.

 

[thepumpguysc]

Depends on what pump u have.
U can loosen the inlet line AT THE INLET of the pump and crank the engine.. fuel should gush out while cranking..
Or u can put a gauge on the filter housing.

The overflow valve should hold 25 psi before it opens.
Unless it’s on a VE pump.. they just have an orifice ..

 

[Andy1845c]

Its a Bosch inline pump. You'd probably know it by heart, but I am not so familiar. Its got an RSV475 on the tag, but that didn't seem to mean anything to the guy I talked to.

Its like this one -

https://www.ebay.com/itm/2665263672...SAHQOOWnOPJByj6m9gxS946WN6-wvtHsaAv6NEALw_wcB

Currently its running off a clean plastic fuel can, but I drained the machine tank to see what I am dealing with. The bottom of the tank has that waxy brown goo that seems to drop out of suspension when diesel gets old. I've had a miserable time with cleaning this this in the past.

 

[thepumpguysc]

If u can finagle the suction and return lines into your bucket, you’ll be able to test the supply pump..
The overflow valve is the banjo bolt that connects your return line to the inj pump..USE THE BIG HEX ONLY TO REMOVE IT.
Use a pick/scribe to push on the ball and spring thru the hole on the bottom of the valve.
That’s a Bosch 4A pump w an RSV gov

 

[Andy1845c]

I can easily get the lines into a bucket.

With the overflow, am I mostly looking to make sure its not stuck open?

Thanks for the correct model number!

 

[thepumpguysc]

stuck open or most likely a broken spring..
If u shake it, it’ll rattle if the spring is broken..
If u push on it w a pick, it should have some tension to it..

 

[Andy1845c]

I didn't see anything obvious. What I did see as I pulled the lines off was a fair amount of crud in the banjo bolts.

Ive got a few gallons of gas in the diesel tank trying to dissolve the wax/sludge at the bottom. Its coming up in globs on the end of a broom handle... what a mess.

Pump is pulled and headed to the rebuilder along with the injectors. We will see what they say.

I do appreciate your help!

 

[Andy1845c]

Just an update for anyone interested - the pump shop called today.

The injectors that were in my machine don't match what his book specs. Compared to whats speced the ones I sent are physically too long - so I am glad they didn't hit the top of the pistons or something.

He said the IP is not in great shape. Going to get a full rebuild. He said the damage was what he would expect with bad fuel. He said there was some rust also.

So I am in for a big bill but hopefully have a running lift in a week or two.

 

[Shimmy1]

Just an update for anyone

He said the IP is not in great shape. Going to get a full rebuild. He said the damage was what he would expect with bad fuel. He said there was some rust also.

Says pretty much ALL pump rebuilders, except thepumpguy, to justify a huge bill. Hopefully it will start when you get it back on. Are you familiar with timing a fuel pump?

 

[thepumpguysc]

Lol.. thanks Shimmy.. I try to always tell it like it is.

 

[Andy1845c]

Says pretty much ALL pump rebuilders, except thepumpguy, to justify a huge bill. Hopefully it will start when you get it back on. Are you familiar with timing a fuel pump?

Well, I hope I am not being took. I've never used this shop before but they seem pretty decent. They have been chatty and willing to share knowledge. I think that says something. Before I sent it to them they told me to check the same things Pumpguy told me to check.

Timing - from what I understand from reading and from talking to the guys at the pump shop this one is about as easy as it gets to time.
The timing pin will be in the pump when I get it back. I need to pin my engine and then install the drive gear for the IP and then snug, pull both pins out and torque. Clean with acetone first. I have no key in mine.
Does that sound correct to you guys too? Ive been lucky and in the 20 years I have been buying and playing with old worn out junk, this is the first IP i have had to mess with.

 

[Andy1845c]

Put the pump back on this weekend and it popped right off in 30F degree weather as soon as I got the lines bled out. Runs great. No on to hydraulic issues.

 

[thepumpguysc]

GOOD DEAL.!!!
Thanks for letting us know..