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

[bikemaniac]

Hi,

I have some issues with my fuel injection pump. As a frame-off restoration the engine was put aside 3 years ago and just recently I fired the engine up again

Here are some data:

1. Engine: L engine (2,2 liter)
2. Mileage: 85000 km - maybe 50000 miles
3. Tank has been cleaned, fresh fuel, new rubber hoses, new fuel filter. Brand new air filter. New engine oil, new coolant.
4. I have not messed with the fuel injection pump - nothing has been touched. Even the idle speed and max speed are in their original position from 3 years ago.

Observations:

1. Basically the engine fires right up and has a smooth and stable idle at estimated 700 rpm. There is no smoke
2. If I flip the throttle a bit with my hand, it responds fast and very well - to estimated 1500 rpm. However I "feel" that I need to flip through some more angular degrees to get response.
3. If I flip the throttle a bit more I sense some sort of hickups or misfiring and operation is not smooth anymore. It sort of feels as if the fuel injectors are starved of fuel for fractions of seconds (maybe air in the system)? I start to see smoke.
4. If I give full throttle the engine is def not able to reach max speed of approx 4500 rpm. It more feels like 3000 rpm and the engine feels more and more sluggish as I rotate the throttle lever towards its max position. Again it feels as if the injectors are starved of fuel. There is a lot of smoke (greyish - def not black or blue) and the smoke smells "wrong". 3 years ago I remember the smoke as being different in smell.
5. I dont have license plates on the car yet so I can basically not drive it in traffic yet, but I made some tests in the driveway: If I put the car in 1st gear and start driving (just releasing the clutch) everything is perfect. If I accelerate in 1st gear, the car picks up speed, but at 10-15 km/h the throttle becomes "unresponsive" and acceleration is not smooth but with the "hickups".
6. As from my memory I feel that the accelerator pedal has to be to be pushed much more as compared with 3 years ago.

Video

At 0:07-0:09 you will see a "hickup" where the engine becomes a bit "confused "and does not accelerate smoothly.
At 0:15-onwards you will see that the engine is not able to pick up more speed even though I have not reached max throttle setting yet.

Questions:
1. Is there a chance that the injection pump has dried out and needs a lot of hard driving where the engine has to do some heavy work before everything settles to normal again? I understand that these tests that I made dont really pull a lot of fuel through the system.
2. Is there a chance that the govenor inside the pump is stuck somehow?

Does anyone have ideas, tips etc on how to solve my problem?

Lucas

 

[Squash]

Reminds me of a diaphragm change on my old 3B. Started and idled fine but on the road for a test drive it made me wonder for a bit, turns out a good ride seemed to make everything just right.

 

[bikemaniac]

Reminds me of a diaphragm change on my old 3B. Started and idled fine but on the road for a test drive it made me wonder for a bit, turns out a good ride seemed to make everything just right.

Where is that diaphragm located?

 

[Squash]

If it's an inline pump there should be a spot to fill and drain the diaphragm.
What engine and year

 

[Squash]

You would add Neatsfoot oil, as this keeps leather supple.

 

[bikemaniac]

If it's an inline pump there should be a spot to fill and drain the diaphragm.
What engine and year

Its an L engine (1984). It is a radial/rotary pump and not an inline.

 

[bikemaniac]

I just made a new test:

I removed the hose from the fuel pump return pipe. I fitted a transparant silicone hose and an empty jar to see whats going on:

1. When the silicone hose is fitted and the engine is off, I manually pumped the priming pump by means of the black knob. In that situation fuel AND air bubbles comes out of the return pipe. When I stop pumping, the fuel keeps running by itself for approx 30 seconds WITHOUT air bubbles.
2. When I fire up the engine, NO fuel comes out of the return pipe, no matter the rpms.
3. When the engine is running and I start to simultanously manually pump the priming pump, fuel and air comes out of the return pipe.

Lucas

 

[Squash]

Try the clear hose from filter or if you get bubbles a jug of fuel directly to the inlet side of pump, You want fuel without air.
You just might have a vaccum leak at primer, filter housing or fuel hose.

 

[roscoFJ73]

If I give full throttle the engine is def not able to reach max speed of approx 4500 rpm.

A sure sign something is wrong with the pump or the fuel supply.


If you pump the hand pump while its not running it has no where to go and you will probably get bubbles. Once the pump goes hard, you should stop pumping.
Running a separate fuel supply from a small fuel can in the engine bay is a good way to isolate problems between injection pump, hand pump/filter and fuel tank.

The bypass valve maybe be not working properly. I posted a video of landrover pump with a blocked valve from a PO using cooking oil.
The valve opens when the pressure inside the pump forces it open and sends excess fuel back to the tank. There should be quite bit coming out of the return line because the rotary pump only uses a 1/3 of it to power the engine in most cases. It uses a lot more on steep hills etc.

I had a pump that was 5 years old and it was full of dried up diesel and needed a strip down. It wouldnt take much to block the bypass. I had all new gaskets and seals put in as well

 

[bikemaniac]

Try the clear hose from filter or if you get bubbles a jug of fuel directly to the inlet side of pump, You want fuel without air.
You just might have a vaccum leak at primer, filter housing or fuel hose.

I just completed the test you suggested: A transparent hose was fitted between the primer pump and the fuel injection pump. No air bubbles at all!

Lucas

 

[Squash]

That's good!
You might clear it out with a good run if you can plate it and run the roads. Otherwise trailer it to somewhere. You can also try Standyne Diesel injection products which should help clean the pump.

 

[bikemaniac]

I did another test with even more transparent hoses.

I need to stress this was not while driving, but just in the driveway where the fuel consumption is low.

1. Transparent hose on the fuel return and directly into a transparent container.
2. Transparent hose between the injection pump and the fuel filter.
3. Transparent hose between the bleed pipe and the banjo on the injection pump which also goes straight to the fuel return line.

Observations:
1. Combining it all I conclude that the low pressure pump within the injection pump is not sucking fuel as it should. I see that the fuel return is very very small.
2. When I push the manual primer pump while running at approx 1500 rpm, the engine starts to run a bit more smooth. Fuel comes out of the return however with many tiny bubbles. It feels as I am aiding the low pressure pump within the injection pump.
3. I did not observe any fuel coming down from the bleed pipe even at high rpms. I bled the injectors once more by unscrewing the unions and cranking the engine - but still no fuel from the return. Maybe there is only return if the load is very high??

Lucas

 

[roscoFJ73]

Maybe there is only return if the load is very high??

The opposite because the engine needs the fuel.

 

[bikemaniac]

I now installed a brand new genuine Toyota priming pump but to no avail.

It becomes more and more apparent that: The injection pump struggles to suck in the fuel - whenever I manually prime when the engine is running, it becomes more stable and is much easier to flip the throttle (ie reach high rpms). If I stop priming idling is nice and smooth but after a minute or so, idling rpm drops a little just by itself. If I prime again, idling increases a bit and becomes more smooth again.

Lucas

 

[too tall]

Sounds like you have an air leak from the fuel supply. As already suggested by others I would take a small fuel can and put it in the engine bay and run a hose directly from the pump into the new supply. If it runs as normal then the issue is the supply. Maybe the sedimenter or the tube that comes out of the tank is cracked? I use a small glass tube filter on the supply side of the pump to see if there are bubbles on the incoming stream.
They would mean there is a leak somewhere before the pump.

 

[bikemaniac]

Sounds like you have an air leak from the fuel supply. As already suggested by others I would take a small fuel can and put it in the engine bay and run a hose directly from the pump into the new supply. If it runs as normal then the issue is the supply. Maybe the sedimenter or the tube that comes out of the tank is cracked? I use a small glass tube filter on the supply side of the pump to see if there are bubbles on the incoming stream.
They would mean there is a leak somewhere before the pump.

I already did that a few days ago. I even used a transparent hose to see whats going on. Still the same problem.

Is there a chance that the pressure regulating valve just behind the inlet banjo is causing all the problems because it is stuck open and the supply pump therefore is basically circulating fuel in its own circuit not sending it off to the high pressure part?

 

[roscoFJ73]

Is there a chance that the pressure regulating valve just behind the inlet banjo is causing all the problems because it is stuck open and the supply pump therefore is basically circulating fuel in its own circuit not sending it off to the high pressure part?

Take off the return hose and see if fuel is coming out

 

[bikemaniac]

As stated previously (I think) there is almost no fuel coming out of the return pipe.

I pulled the regulating valve out now. It is not clogged and it moves with the spring. However I noticed: It was stated somewhere that the supply pump delivers at 100 psi which is about 7 bars. So the pressure valve should open at 7 bars. By making some quick calculations, estimating the cross sectional area of te small piston I feel that I need WAY too little force to push it open. More like 1/10th of the calculated force based on 7 bars. At 1/10th the small piston just opens the 4 small holes.

Lucas

 

[Nz Nath]

I thought rotary pumps supply was more in the range of 8-13psi.

If you're not getting fuel out the return line then surely your main suspects would be lift pump and blocked prefilters/gauze/tank pickup.

 

[roscoFJ73]

However I noticed: It was stated somewhere that the supply pump delivers at 100 psi which is about 7 bars

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.