Power problem

[moots'r'us]

Afternoon all

A while ago I had to carry out some work to get the old bus through the MOT. Part of this involved changing the 'o' rings in the fuel pump as per the bongo fact sheet.

Cured the fuel leak and passed the test but left me with a different problem that as yet, I have not been able to cure so if anyone can throw in some suggestions I would be very happy!

The old girl seems now to be as flat as a pancake! There seems to be no go in her when accelerating. Between 40 and 50, if you engage the kick-down, it drops down ok, but almost like its dropping to second and not third. Loads of revs but no increase in road speed. The change between third and fourth seems to be very close together as well.

Before I did the 'o' rings, she had loads of grunt for a big old bus and would change gear perfect. Now, you have to almost feather the throttle to get the gear changes to happen, indeed changing from first to second almost requires you to feather the throttle otherwise it just seems to stay in the lower gear and rev like mad.

Not sure what the bit of pump that was removed and re-fitted does and if it could cause the problems I am getting or not? Only other area that may have been disturbed is where the MOT guy had his inspection light passed up through the sump cover by the gearbox end whilst looking to see if the fuel leak had been done.

Help! its driving me mad!

Adrian

[francophile1947]

Those are exactly the symptoms I got when my fuel filter blocked. Maybe some muck was released when messing with the pump. Also check the banjo filter.

[mikexgough]

I would change the fuel filter as John says, mind you I have got the pump seals to do as mine have just started leaking.... oh well better just get on with it in the morning, deep 10mm socket with driver, mirror and a ratchet 10mm spanner at the ready.....

[daveblueozzie]

When you change the fuel filter, top up the new filter with jet cleaner before you screw it back on, its then primed,and the same time will clean the jets out .and dont forget to give the banjo filter a clean like John said.

[moots'r'us]

Hi all, thanks for that.

When I changed the 'o'rings, I also changed the fuel filter and had the banjo out. That was clean as well.

Does anyone know what the little cup that you remove to change the 'o' rings actually does? Could disturbing that be related to the power issues do you think?

Mike, good luck mate, that has got to be THE worse job I have ever done on a vehicle! Such an easy job, but so bloody frustrating!!

The thing that puzzles me is that it is affecting the gear changes. I would have thought that it would change up / stay up and just be underpowered rather than reving its nuts off in the lower gear?

Adrian

[mikeonb4c]

Mike, good luck mate, that has got to be THE worse job I have ever done on a vehicle! Such an easy job, but so bloody frustrating!!

He's right! All I got for trying was a week in bed after doing my back in. The combination of working bent over, specs perched on my nose, slippery spanners dropping into secret places, and the scary thought that having got it in pieces (if I was that lucky) and without springs causing components to fly out and get lost (or even prevent me from seeing which order they belong in for re-assembly), my back giving out all the while and adding to my distraction...........was too much for me. If I'd have been self employed, it would have been an expensive mistake!

OK so Dandywarhol did it, but he's superhuman and has small hands (by his own admission). Even he admitted to having seriously grazed hands at the end of it.

Adrian in Bury (well known Bongo mechanic) made it clear he would only do that job after removing the pump from the vehicle (not a job for beginners as it all has to be retimed afterwards I believe).

Harry got lucky and found a fit young mechanic in Cumbria who was able to do it 'in situ'.

Be careful Mike. The TU movement does not need you to be out of action in times like these

[dandywarhol]

The "cup" and its colleagues are an essential part of the pump which control the cam ring http://www.turbodieselregister.com/foru ... ost24.html which will affect performance.

Also on the pump is a vacuum hose which is easily displaced and allows extra fuel to de delivered during turbo boost time - which seems to be when your problems happen.



Also, the Throttle Position Sensor (TPS) is the electrical switch gubbins which tells the gearbox when to change up/down.

Any of these areas could be affected when working on the pump. first check the vacuum hose from the front of the engine to the round diaphragm device on the pump (where part 1320 and the pointy finger shows on this diagram http://www.lushprojects.com/bongopartsm ... mgno=.html

The gearchanging faults sound reasonable because the box will respond to the input that the TPS gives the ECU, in other words, how much welly you're trying to give the engine........................

[moots'r'us]

Sorry about the delay in getting back but been a bit manic

Thanks for the responses guys! Finally managed to lift the seat at lunchtime and check out the areas suggested by dandywarhol

The pipe is clear and seems to be in reasonable nick. I removed the pipe from the diaphragm end and with the engine running observed air being blow out. Is this what is expected? Only thing I did find was that the pipe is a bit of a slippery fit on the stub of the diaphragm. Not sure how much resistance is put up by the mechanism but wondering if under load it is simply escaping from the pipe end rather than operating the mechanism?

Everything else seems to be in place. Only other thing I was considering was the removal of the cup and associated springs again to see if anything has gone pear-shaped there!

[BongoMTBer]

When you took it apart, did you take the throttle position pot off? If so, did it go back together with the little flat on the spigot lined up with the nylon connector correctly. The output from this pot is put into the equation when the ECU decides when to change gear, so maybe worth a look.

[BongoMTBer]

Sorry Dandy, just read your post

[BongoMTBer]

Moots. have you for any reason removed the cap off the diaphram?

You can adjust the amount of boost fuel by rotating the diaphram.

[moots'r'us]

hi there,

all I took off was the items listed in the fact sheet. On the pump itself, only the cup and blanking plate opposite and behind the pump. Just wondering if any of the springs may have become snagged inside the cup? If the advance and retard side is playing up then i guess that can have power issues? All i do know is that it is pain to drive at the moment

Apparently, it smokes a bit as well when pulling away but i think that might be down to me giving it a bit more stick to get it going!

[The Great Pretender]

I had something very similar, as if the TPS was out of sink. It turned out to be the thimble filter at the inlet of the pump reducing fuel flow.

[moots'r'us]

cheers..... I will investigate said thimble!

[ronhud]

Moots - its usually referred to as the banjo filter. It is deep down under the bolt and I would reccommend that when withdrawing the bolt take great care not to lose the various washers, collar etc and note the order that they are assembled together. Sorry if I am showing my grandmother etc.........
Ron