Stalling Issue

[woody127]

Well it's been sometime since I've done any posting here, but here's an update on my M1009. Was (still) having issue with my truck stalling out under load. As I previously stated, the truck will start up and idle with no issue. It's only when I drive it that it stalls out. So I took it to a "diesel repair shop and explained in detail what we did (replaced fuel sending unit in tank, uplift (mechanical fuel pump on side of engine), changed out fuel filter. Fuel is clean and flows freely from bleeder on filer. It was suggested that the injector pump may be failing. I told the shop no great rush, but it's been 2 months, and nothing yet. It seems after talking to the owner of the shop, his mechanic doesn't know what to do and they didn't want to fire the "parts cannon" at it. These people have been in business for years and it's hard for me to believe that a basic diesel mechanic, can't figure out what going on with the M1009. I understand that she's 35 years old and the new breed of mechanic may not get it. If my health issues weren't a problem, I'd work on the darn thing myself. Sorry 'bout this post, it's just frustrating that it has taken them 2 months to figure out the issue. I've evening given them this web site to look thru and others dealing with a 6.2 liter diesel engine. Is it the NEW mechanics, don't know the basics?

 

[Squibbly]

My brother (who knows more than me about these things) had me swap this fuel hose going into the injector pump out with some clear fuel hose, and look for air bubbles, which I saw and it was because of a leaky lift pump and hard line.



If it were happening under load, I'd probably strap my phone or camera into the engine on record and pointed at that line, and put it underload to see what was happening to the fuel before reaching the injector pump.

Just a thought.

 

[Keith_J]

Definitely a fuel flow issue. Does it do this only in motion? Or can you replicate the problem with holding the brake and opening the throttle?

The injection pump is quite simple. In a diesel engine, power is controlled solely by injected quantity. In this pump, injected quantity is controlled by transfer pressure and the metering valve. Transfer pressure is a function of engine speed to offset the decreased charge time with increasing speed..the port that allows fuel to flow into the pumping chamber has decreasing open time with increasing engine speed.

Yes, air in the fuel supply will cause issues. A failed lift pump can do this as the transfer pump can suck fuel past the lift pump. Also a plugged case drain will also cause stalling with increasing speed as the pumping chamber cannot fill.

Debris in the injection pump can plug the fuel return, causing excessive case pressure. Earlier injection pumps have an elastomer flyweight drive bushing which breaks down, forcing debris into the case drain since this is a pressure release valve. There is also a cold start pressure relief solenoid, energizing the green wires reduces case pressure when cold. This also advances timing..

It isn't difficult to remove the top cover to check for broken elastomer drive bushing parts in the injection pump. Black bits in the case will cause pressure issues. Rebuilt pumps can use a flyweight cage that doesn't need this bushing.

 

[woody127]

Definitely a fuel flow issue. Does it do this only in motion? Or can you replicate the problem with holding the brake and opening the throttle?

The injection pump is quite simple. In a diesel engine, power is controlled solely by injected quantity. In this pump, injected quantity is controlled by transfer pressure and the metering valve. Transfer pressure is a function of engine speed to offset the decreased charge time with increasing speed..the port that allows fuel to flow into the pumping chamber has decreasing open time with increasing engine speed.

Yes, air in the fuel supply will cause issues. A failed lift pump can do this as the transfer pump can suck fuel past the lift pump. Also a plugged case drain will also cause stalling with increasing speed as the pumping chamber cannot fill.

Debris in the injection pump can plug the fuel return, causing excessive case pressure. Earlier injection pumps have an elastomer flyweight drive bushing which breaks down, forcing debris into the case drain since this is a pressure release valve. There is also a cold start pressure relief solenoid, energizing the green wires reduces case pressure when cold. This also advances timing..

It isn't difficult to remove the top cover to check for broken elastomer drive bushing parts in the injection pump. Black bits in the case will cause pressure issues. Rebuilt pumps can use a flyweight cage that doesn't need this bushing.

Thank you Sir, will forward to mechanic.

 

[MarcusOReallyus]

Is it the NEW mechanics, don't know the basics?

Yep. If they can't hook up a scanner and get a code, they have no idea what to do.

 

[woody127]

Yep. If they can't hook up a scanner and get a code, they have no idea what to do.

Marcus, just like at our Subaru dealer, with a computer they figure out what is wrong.

 

[nyoffroad]

Thank you Sir, will forward to mechanic.

I hate to say it but do you really think he will read it let alone understand it? I'd be looking for a different shop/mechanic. How far are from CUCVUS

 

[LT67]

Sounds like the wrong lift pump is on the engine...

Go back and check which mechanical lift pump was put on the engine. If it was Delphi MF30030, then it is the wrong lift pump.... been there done that with the same issues you are having.

The CORRECT lift pump is Delphi CHFP906. I swapped that pump back onto the engine and it fixed it. Hope this helps...

 

[Keith_J]

How things change..30 years ago, mechanics couldn't understand electronic and computer controlled drive trains.

I do both, country and western

 

[Skinny]

Yikes

I'd get my truck out of there ASAP!

I get it, lots of techs are trained on certain vintage of vehicles and that is what they know. I've worked at dealerships and trained techs. Some know what you give them, some know because they research on their own. Doesn't make them a bad tech, they just do what they do because that's what they work on.

I have a serious problem with a diesel shop that doesn't know a mechanically injected diesel. Doesn't matter if it's GM, Navistar, John Deere, etc. It's got a lift pump, some filters, and a fuel dizzy. It's not rocket science. Hell most of it is only made by two or three companies. It's been like that for decades before common rail came on the scene.

If they can't figure it out and are loading the parts cannon get out. The only freaking parts are the lift pump, filter, IP, and injectors. What other parts are they replacing here? You can literally replace all of them and sit back for another 30 years till they need to be replaced again.

 

[woody127]

I hate to say it but do you really think he will read it let alone understand it? I'd be looking for a different shop/mechanic. How far are from CUCVUS

we live in Southeastern PA, on the boarder of Philadelphia

 

[MarcusOReallyus]

Make this simple. Check the lift pump.

Then see where you stand.