Still not starting or idling

[Crf450x]

I’m not sure how to check the pressure from the lift pump. It is the 2nd brand new one from Cummins though and the engine does the same thing. Once you start it with ether you can drive it around and it will idle in neutral. You can turn it off and immediately try to crank it and all it does is spin.

I wonder if the overflow spring is broke. Just a thought. I’d pull the valve out and have a look.

If it’s in the same place as a p7100 it’s on the inside toward the front of the pump. It looks like a banjo bolt with another bolt screwed into it. Look up a YouTube video first. There are shims that can fall out.

 

[simp5782]

Ok I will give this a shot but I guess I don’t understand why I can start it with a squirt of ether in the stack and it will sit there and idle in neutral all day if it’s the trans

Fuel settjng

I’m not sure how to check the pressure from the lift pump. It is the 2nd brand new one from Cummins though and the engine does the same thing. Once you start it with ether you can drive it around and it will idle in neutral. You can turn it off and immediately try to crank it and all it does is spin.

Did you replace the fitting at the lift pump that is a 90 degree fitting where fuel enters the pump?

 

[WillWagner]

So the engine will not turn over, as in no crank after shut down? 600 is low. Look on the engine data plate, I believe idle should be 700. Checking fuel system as follows.

In the picture,
Restriction from the truck, yellow circle.
Lift Pump output pressure, black circle.
Pressure drop across the filter, blue circle OR white circle at the inlet fitting on the pump. makes no difference.
Fuel pump inlet fitting, white circle.

If you want to check for air in the system, install a clear line from the blue circle to the inlet of the pump, the line should be looped.

No more than 4 inches restriction, 4 psi drop across the filter, gallery pressure should be 20 psi min, 25-30 is normal for a good used overflow valve. The lift pump is capable of 70 psi. Also it is normal to see the gauge needle bounce when checking gallery/filter outlet psi, you can dampen the preddure by installing a needle valve in the test line.

Other things that can cause a no start or low idle/not idling with a load are air in the system, the FSOV not pulling in all the way, low curb idle, low fuel pressure

 

[Guyfang]

Ok so I finally got around to working on my m923a2. Changed the dip tubes (stainless), put all new Parker push lock fittings and lines from tank to lift pump and from tank to return on injection pump. New lift pump and cleaned tank completely. Also new fuel filter.
Truck will crank with stating fluid and stay running as long as you keep it revved to about 800. It will also drive around but has no get up and go. As soon as you let off the pedal and push the brakes the truck idles down until it dies. It won’t crank back up unless you spray stater fluid in the intake.
I broke all the lines on the injector pump while it was running and I get a strong spray from each one.
pulling my hair out over here

Hi,
I am a generator guy. But an engine is an engine. So here is a question no one has asked. Did the truck run before you started changing and fixing it?

 

[theanimal]

Hi,
I am a generator guy. But an engine is an engine. So here is a question no one has asked. Did the truck run before you started changing and fixing it?

The truck ran like a clock years ago. It would pop off without even spinning a full revolution. The truck sat for about a year and it would start but it was hard.
eventually It stopped starting all together. I pulled the tank and cleaned it and changed the lift pump and filter. No change. I then changed the dip tubes and put all new hoses from the tank to lift pump and from injector pump to tank.
still no change.

 

[theanimal]

Fuel settjng


Did you replace the fitting at the lift pump that is a 90 degree fitting where fuel enters the pump?

Yes I changed them all

 

[WillWagner]

If you checked pressures and they are where they need to be, I would pull the injectors and have them tested or just get another set. That what I would suggest if all the testing was done. If you have checked pressures, isolated the engine from the chassis, chances are injectors are messed up.

Here is something to check that will verify injector issue. The injectors have almost zero return fuel, at rated load and RPM there is just a few drops coming out of the return from the injectors. The return dumps into the pressure filter inlet. That banjo bolt is nothing special other than it is tapped for the 6mm banjo for the return. If you can find another banjo for the outlet of the filter head OR make a spacer that you can install instead of the return line, start and run the engine with the injector return line off of the filter head. If there is any return flow, other than a drop or two, the injectors are junk. Honestly, IIRC, return flow is only 2cc at rated HP/RPM in 60 seconds.

 

[WillWagner]

Any progress?

 

[theanimal]

Any progress?

Not yet man. I run my own business and I just haven’t had the time to work on it. I can tell you that I checked the return fuel from the IP the last time I tried to figure this out and at idle the fuel flows freely. But I don’t think that’s what you mean. i spoke to someone the other day about testing the injectors but they wanted almost $500 to test.
do you know of a cheap source for injectorsfor these motors? I think rebuilt would be fine if that’s a cheaper option.

 

[Guyfang]

There is no idle for this gen set. It is suposed to run at rated volts and 6o hertz. Loaded, or not. NEVER idle.

 

[theanimal]

There is no idle for this gen set. It is suposed to run at rated volts and 6o hertz. Loaded, or not. NEVER idle.

What gen set?

 

[Guyfang]

Sorry, sorry, sorry! I was toggeling between three generator threads, and made a mistake. Sorry again.

 

[EO2NMCB]

Not yet man. I run my own business and I just haven’t had the time to work on it. I can tell you that I checked the return fuel from the IP the last time I tried to figure this out and at idle the fuel flows freely. But I don’t think that’s what you mean. i spoke to someone the other day about testing the injectors but they wanted almost $500 to test.
do you know of a cheap source for injectorsfor these motors? I think rebuilt would be fine if that’s a cheaper option.

http://dieselparts.com/
Check with Premco Lamlasas TX. Got a set of rebuilt injectors for a Nhc250, truck starts great and runs like a top now, was 75 per injector, 25 core core charge ea. Simp5782 had told me about them.

 

[WillWagner]

Not yet man. I run my own business and I just haven’t had the time to work on it. I can tell you that I checked the return fuel from the IP the last time I tried to figure this out and at idle the fuel flows freely. But I don’t think that’s what you mean. i spoke to someone the other day about testing the injectors but they wanted almost $500 to test.
do you know of a cheap source for injectorsfor these motors? I think rebuilt would be fine if that’s a cheaper option.

The pump returns a boat load of fuel. To see if it is an injector issue you need to see if there is flow from the injector return....the small line that is on top of all the injectors that terminates at the fuel filter inlet fitting. The injectors use every drop of fuel supplied to them, there should be no flow from them. If you remove the line from the top of the banjo bolt at the fuel filter inlet fitting, plug the hole in the fitting and run/try and start the engine and fuel pours out that line, no reason to test the nozzles, they are plugged and need repair or replacement.

 

[theanimal]

Does anyone know if part #4025299 is the right one for our injectors? They say marine but I’m not sure why there would be a difference.
thanks

 

[WillWagner]

The book I have doesn't have p/n's that high, it was published in 1997. Call Cummins, you'll need your engine s/n. A good parts guy can figure out what uses that p/n injector. Usually, marine injectors are flowed higher than automotive. Boats don't have down hill, they are constant power applications. An automotive engine rated at 250 would be 300-325 marine rating. The C and L series engines, at the time that I left Cummins, were pushing 600 HP. There are also pleasure craft and work power ratings. Pleasure craft were higher for the same engine because they are not used on a daily basis/full time. Recretional ratings were usually 50-100 hp higher rating than Vocational ratings for the same engine. CPLs were different to differentiate the power ratings. Base engine parts were generally the same, mainly fuel system parts were different with the exception of the cylinder head swirl factors.