Faulty injection pump: Uneven acceleration (with video) (1 Viewer)

[bikemaniac]

I would double check this figure. I remember that post and thinking it sounded high. I didnt think the gaskets and seals would have handled that pressure.

Im not sure if its been mentioned, but setting up a temporary fuel supply that bypasses the filter would have told you a lot.

If I make the temporary fuel supply with transparent hoses I notice that the fuel return is very very little - close to nothing. It is as if the fuel initially supplied by the priming pump is used used up by the injectors for a minute or so and then the supply pump starts struggling keeping up with the demand with the result that almost nothing goes to the return line because everything is used for the injectors.

 

[mudgudgeon]

If you're sure all your hoses etc are good and you aren't getting air into the fuel supply, maybe try running an injector cleaner or something through it from a temporary fuel supply.
If it's been sitting for years, and dried out it could be gummed up internally.

You described greyish smoke that smells wrong.
Sounds like unburnt raw fuel.
With a rotary pump, unburnt fuel and stumbling acceleration can be the result of air in the system.
Air in the fuel lowers pressure inside the pump casing and retards injection timing.
If the timing is retarded you get unburnt raw fuel and white-pale grey smoke that stinks of raw diesel.

If air isn't the problem, in guessing the timing advance is gummed up.

If it's stumbling when running with no load, is going to be a lot worse if you try to drive it

 

[roscoFJ73]

If I make the temporary fuel supply with transparent hoses

If you put the tank above the injection pump, it will gravity feed and it should run ok even with a bad feed pump.
If you lower the tank below the injection it will not gravity feed if the feed pump is worn out as.
This is one way of isolating the problem
You need to get the rpms up and observe the fuel return. At idle its probably just a dribble.
I would run the fuel return to a separate tank/bucket to make it easier to see how much came out.

Going back to your original post it says 85000klms. A feed pump doesnt wear out in a short time like that unless it was left with moisture laden fuel in it. This will cause corrosion. Usually a feed pump is among the last components to wear out.

Unless you find a massive air leak which is quite possible, I think you will be up for some $$$ at a diesel injection shop

 

[bikemaniac]

At idle its probably just a dribble.

There are mixed answers on the fuel return amount. I have to admit that I support the idea that the fuel return must be large, because:

Lets say you are driving uphill in 1st gear even with a trailer. The fuel consumption must be enormous since the engine is working like mad. That could even happen at lets say 1000 rpm, very close to idle, where the pedal is floored and you are towing a heavy trailer uphill. Even at 1000 rpm the supply pump HAS to "overproduce" fuel and thus enable fuel to the tank. Towing uphill will maybe require 20x more fuel than idle. But the key is, the supply pump does not know how much fuel is required by the system - only the govenor knows that. It just has to supply fuel to make the govenor happy at all times and for the fuel supply only the rpms are the major control mechanism: If I run at 1000 rpm, the supply pump should supply x amount of fuel. If I run at 2000 rpm, the supply pump should supply 2x amount of fuel.

Or is the observation wrong?

Lucas

 

[roscoFJ73]

The rotary pumps on a 1HZ are good for up to 54 litres an hour(the manual says 900cc a minute} and you can use close to that for short periods of heavy acceleration on a steep hill take off. Obviously a 2L engine would be a lot less
But at freeway speeds its down to about 12/100klm for a 1HZ at 2750rpm, at that speed it could be sending 2/3rds of the fuel back to the tank.
A guy named Jan who used to frequent this forum emptied the return from his 1HD T into a container and said the returned amount was substantial, but I dont think he measured it.

 

[Nz Nath]

I ran the return on my 13bt into a Jerry in the cab, and it returned at steady rate no matter what, idling on the drive or foot flat up a big hill. I didn't measure the volume but I wouldn't have wanted to go for a long drive.

I just had my lift pump rebuilt by an injection shop. Cost 190nzd, of which over half was labour. The old piston had visable wear, and scoring which you can feel with a finger nail. I can't imagine it would be too hard a job to do yourself.

 

[Squash]

Run your fresh fuel and injector cleaner directly to the IP intake bypass the primer/filter.
Hopefully you can run long enough to get everything hot.
Ideally you can drive it, or say screw the law and take her for a rip.

 

[bikemaniac]

I have some new information since I got help from my dad:

1. I put the regulating valve back into the pump. It had been thoroughly cleaned.
2. I let the engine run hot by idling for 1h and kept playing with it, also driving uphill in the driveway. I figured that the hot engine would warm up the diesel fuel in the pump and ease the looseing of sticky gummed up fuel or something similar. I did not help at all.
3. When sitting in the car and playing with the pedal/throttle everything sounds smooth and the engine is not shaking besides the small hickups and problems reaching max rpm at approx 4500 rpm. Similar, the engine becomes "confused" when driving uphill in 1st gear and for the last 50% of the pedal stroke, nothing happens (with smoke generation).
4. As mentioned before, the engine sounds good in the engine compartment at lets say 1500 rpm, but at the exhaust, there are noticable more hickups and misfirings with smoke generation. Hence there is a definite difference between the exhaust pipe and the engine compartment.
5. I put a piece of paper below the exhaust pipe and noticed that the exhaust spits out some oily substance at elevated rpms when the smoke is generated also. Nothing is spitted out when the engine is idling only. I cannot figure out if the oily substance is diesel fuel or engine oil - my own laymans guess would be engine oil.
6. Without sufficient knowledge I would now think I have at least 1 faulty injector which isnt able to open sufficiently (it opens at low load, but not sufficiently at high loads). But I had all 4 injectors tested in a professional workshop 2 years ago where the specialist told me that their spray pattern is almost like new. I admit that the injectors have been laying around for 2 years.

Lucas

 

[roscoFJ73]

I ran the return on my 13bt into a Jerry in the cab, and it returned at steady rate no matter what, idling on the drive or foot flat up a big hill. I didn't measure the volume but I wouldn't have wanted to go for a long drive.

I just had my lift pump rebuilt by an injection shop. Cost 190nzd, of which over half was labour. The old piston had visable wear, and scoring which you can feel with a finger nail. I can't imagine it would be too hard a job to do yourself.

Are you talking about an inline pump?

 

[roscoFJ73]

I have some new information since I got help from my dad:

1. I put the regulating valve back into the pump. It had been thoroughly cleaned.
2. I let the engine run hot by idling for 1h and kept playing with it, also driving uphill in the driveway. I figured that the hot engine would warm up the diesel fuel in the pump and ease the looseing of sticky gummed up fuel or something similar. I did not help at all.
3. When sitting in the car and playing with the pedal/throttle everything sounds smooth and the engine is not shaking besides the small hickups and problems reaching max rpm at approx 4500 rpm. Similar, the engine becomes "confused" when driving uphill in 1st gear and for the last 50% of the pedal stroke, nothing happens (with smoke generation).
4. As mentioned before, the engine sounds good in the engine compartment at lets say 1500 rpm, but at the exhaust, there are noticable more hickups and misfirings with smoke generation. Hence there is a definite difference between the exhaust pipe and the engine compartment.
5. I put a piece of paper below the exhaust pipe and noticed that the exhaust spits out some oily substance at elevated rpms when the smoke is generated also. Nothing is spitted out when the engine is idling only. I cannot figure out if the oily substance is diesel fuel or engine oil - my own laymans guess would be engine oil.
6. Without sufficient knowledge I would now think I have at least 1 faulty injector which isnt able to open sufficiently (it opens at low load, but not sufficiently at high loads). But I had all 4 injectors tested in a professional workshop 2 years ago where the specialist told me that their spray pattern is almost like new. I admit that the injectors have been laying around for 2 years.

Lucas

When diesels sit around for a while, they often spit out black soot for a short period.
You need to get something working properly. With a suspect hand primer , suspect injector, suspect governor, its impossible to get a starting point. You have one problem for sure, but how many others?

 

[mudgudgeon]

I agree, you haven't isolated the fuel supply as a possible problem

Use a 5 litre Jerry can, run some hose directly to the pump, run the return line back into the Jerry can.
Add some injector cleaner, or 5% petrol to try and clean things out.
Secure it in the engine bay and take it for a spin to get everything warmed up thoroughly.

I think it's fairly unlikely to be a problem with the injectors even though they have been sitting.
More likely to be an issue with dried up old fuel in the injection pump.
If an injector is stuck closed, you'd get a consistent miss, not an intermittent miss, and it won't cause smoke.
If it's stuck open or dribbling, I think you'd be seeing black smoke not white smoke. Black smoke is from too much fuel.
White smoke is unburnt fuel, and stinks strongly of diesel.
White smoke is indicating a timing problem which again can be the result of air in the fuel, or a problem with the pump.


If you were getting engine oil out the tail pipe, smoke would smell of burnt oil, not diesel. The only way for engine oil to get into the tail pipe is through the cylinders past rings, or past valve seals. Either way it will burn first.

If it's cold where you are, you could just be getting condensation and diesel soot spitting out the tail pipe. Water vapour is a by product of combustion. This is normal until the exhaust system hears up enough that water vapour doesn't condense against the child exhaust pipe. Sitting in the driveway, it's not likely to get hot enough.