High idle with Bosch Pump

[Mac1984]

Hi all,

Hope somebody has an idea about the following symptom :

Recently my Bosch pump ha started to rev very high in idle.

Apart from that everything is normal, but if I stop say at a traffic light, the rev counter shows between 1200 to 1500 Rpm in idle. I tried the following :

Checking the throttle cable, if it maybe is stuck or something, but it's all looking normal.

When I move the throttle at the pump by hand, and kind of move it back into position very fast, the pump goes back to normal idle speed, sitting around 800rpm or so. As soon as I drive, the story starts again. I reversed into my driveway there earlier, idling around 1500 Rpm, opened the bonnet, moved the throttle back quickly by hand, and immediately the pump went back to normal idle speed. What I don't understand is the following :

When the pump revs high, the throttle lever is at exactly the same position, means it sits properly against the stop screw at the back, yet it revs higher then usual?

Could that problem be underneath the lever? Anyone had that problem before?

Every idea is much appreciated

I have not altered anything on the pump before this happened..

[V184]

cold start sticking

[Bruce e]

Could be the gouverneur inside the pump sticking

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[psrountree@gmail.com]

I have exactly the same problem. Only happens when the motor is up to temp. If I stop with it in gear and my foot on the brake (like waiting at lights), I can ease the clutch out (like a stall), and the revs drop back to 800 and stay there until I accelerate again. It will sometimes drop back on its own after 20 or 30 seconds, but I usually get impatient. It used to rev at 1200 but is now up to 1500.

The guy that installed the pump thinks I have picked up a little dirt in fuel that has worked it's way through and is catching in something in the governor. The starting price to fix it is $2000, so I will put up with it until someone has a more positive idea.

Our Transit is a 98 LWB cab-over motorhome in Australia. 320,000 Km. The Bosch pump has been in 5 years, have this problem for 2 years. Any ideas ?

Peter


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[Mac1984]

That seems correct with the warm engine.

After the first cold start the revs are normal.

Maybe this can be solved with clean fuel/ some sort of additive?

I will also try and get a new fuel filter tomorrow.

2000 bucks for dirt in the pump seems a bit steep no?

Surely if that is what happened the dirt must come out again as well?

My Transit is 98 as well and I have currently 310.000km..

Must be the age and mileage when they reach their mid life crisis then..

[Mac1984]

I correct myself:

I did a cold start there earlier, the idle was normal.

As soon as I touched the accelerator, the idle jumped up to approximately 1200rpm.

So its not just with warm engine, it seems whenever I move the throttle. Then it sticks to the high speed idle.

Will it be possible to get the governor out for cleaning?

I will try to get a new fuel filter and some diesel additive tomorrow, and see if that gives any improvement.

[psrountree@gmail.com]

Hi Mac, I have used a diesel additive for years. I will follow your progress with interest, hope you can find a cure.

Peter


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[Mac1984]

I think I have found the culprit.

As I don't know all the parts names, I describe it as good as I can:

The throttle lever rests on this big spring and a black plastic housing. From the top through goes a shaft with teeth on, I assume this will be the shaft from the governor. On top of this shaft is a nut, which was loose. So what happened was that when I accelerated, the shaft was turned with the movement of the throttle lever, but when I let go, the throttle lever went back into its idle position, but because the nut was loose the shaft slipped through. So even when the throttle was in idle position, the shaft itself wasn't.

I have removed the top of the throttle lever assembly, kept the shaft in position with a flat screwdriver while I have tightened the nut, and the result is... The Problem is gone.

Drove down the motorway to work this evening, and every time the engine went back to normal idle speed.

Maybe its worth to check this nut on your setup, Peter.

Your Problem might be a different one, but since we had similar symptoms, it might be worth checking.

Greetings from the emerald isle

[psrountree@gmail.com]

Hi Mac and thankyou ! I will have a look in daylight tomorrow, can't wait !

Peter


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[psrountree@gmail.com]

I had a look and could not see a fault. Saw my mechanic today and and he said sorry, no easy answer. Probably 9 months before we do another big trip, something may come up in the meantime. Here's hoping !

Peter


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