Bosch diesel fuel injector pump output test - SOLVED

romie · Post by **romie** » 16 Jul 2010, 13:21

Hi,

If I crack the fuel line going into one of the injectors how much fuel should I be expecting to be expelled?

Below is a youtube video of the one of the outputs from the fuel pump going to the injector, does this look like there is too little being ejected?
http://www.youtube.com/watch?v=KxhsvZceuh0

Many thanks

Post by **Peter.N.** » 16 Jul 2010, 13:32

At tickover about the size of a pinhead and full throttle about a matchead, may be a bit more with the pipes disconnected, if there is any discernable fuel the engine should run, assuming the pump timing is in order.

romie · Post by **romie** » 16 Jul 2010, 13:57

Hmm, as you can see there is something going to the injectors so I suppose this bit of the pump is ok then.

I found an example of how much fuel should be coming out of the injection pump distributor on youtube.
http://www.youtube.com/v/pUnMel8EdnQ
At the injector mines nothing like this :s

Post by **Peter.N.** » 16 Jul 2010, 14:15

I couldnt see any fuel in your video, certainly it didn't look like that one, the ammount I referred to was the ammount burnt per stroke, in the second video its obviously delivering a lot more when not under pressure. Will the engine not start, do you get any blue/white smoke from the exhaust when turning it over? Is there plenty of fuel being delivered into the pump from the filter?

romie · Post by **romie** » 16 Jul 2010, 14:36

ah, sorry Peter.N. I didn't mean to create another thread on the whole problem. Could I refer you to the below topic regarding the actual issue, your input would be greatly appreciated

Xantia 1.9TD Estate 1996 died whilst running, now won't run.
http://www.frenchcarforum.co.uk/forum/v ... highlight=

The Xantia will eventually start after 3mins turning her over with foot to floor but will die when revs go below 2000rpm - no smoke.

I've removed stop solenoid internals and bypassed everything I could by gravity feeding fuel through transparent tube directly into Bosch injector pump which, when running, it drew in.

Hmm, cheers

Post by **Peter.N.** » 16 Jul 2010, 18:14

Well, I have never known one of these pumps to fail, but it sounds as though yours might have done. The only time I have had these symptoms was on an old Perkins 4/108 engine and this was caused by a blocked return pipe from the pump, the engine had run out of water and had got so hot that it had melted the plastic pipe!

Might be an idea to check the return to make sure its flowing freely, any obstruction will increase the pressure within the pump which will upset it. Try starting it with the return disconnected, but not for long as it will pump fuel out everywhere.

Peter

Post by **CitroJim** » 17 Jul 2010, 06:25

Peter.N. wrote: Might be an idea to check the return to make sure its flowing freely, any obstruction will increase the pressure within the pump which will upset it.

Very good thinking Peter.

This problem is starvation of sorts and if you've tried a direct feed then the pump itself or a blocked return line seems to be the cause.

I've disassembled a few pumps now and found those that have run in the past on "exotic" fuels are terribly contaminated by gum which I believe results from the polymerisation of said fuels over time. Diesel won't shift it and the only stuff that does is petrol.

I'd suspect the pump is badly gummed and a passage or two is choked or the transfer pressure relief valve is gummed open which will result in the pump being unable to generate sufficient transfer pressure.
Another cause my be a blocked internal gauze filter basket in the distributor head between the stop solenoid and HP pumping element.
Another area where gumming can wreak havoc is on the lift pump vanes. They can stick and seriously reduce the efficiency and again lead to very low transfer pressure.

A strip and clean should restore normality.

Another cause on AS3 pumps can be wear/blockage on the timing device whereby the timing device keeps the pump fully retarded. Again, symptoms will be hard starting, no rev and lots of smoke.

romie · Post by **romie** » 23 Jul 2010, 10:48

Ah, fantastic guys. It does look like I'm going to be removing and stripping the pump at some point.

I've been swatting up on how the whole thing functions and think I've got a good basic idea.

Here's another video of the output from the pump at the distributor head:
http://www.youtube.com/watch?v=p-gFWNGZE84

Does this confirm/follow on with the restricted flow consensus?

I've never run this vehicle on anything other than straight diesel but that's not to say someone else hasn't used some sort of

exotic

fuels in the past.

I'm going to first try removing the pump without taking the pump gear/timing belt off.

Anything I should look out for when removing the pump?

Thanks for the comments, I'll be using them as a guide while the pumps in the vice

MikeT · Post by **MikeT** » 23 Jul 2010, 14:10

romie wrote:Anything I should look out for when removing the pump?

Yes. Be aware there's a wooruff key in the main shaft, which the pulley locks into.

Also, if you're going to remove any banjo's, they are dedicated inlet and outlet, if you get them wrong, it'll starve the pump of fuel

Otherwise, it should be a simple job of spannering. Do also bare in mind, you don't want any muck getting into any fuel orifice so try to clean the areas before undoing couplings to the pipes etc.

romie · Post by **romie** » 27 Jul 2010, 10:05

oh - my - life!

ok, pump off. But it was not without protest.

No one mentioned that damn bolt under the pump >:)

One spanner cut in half and many - many - many retrievals using a magnet on a stick.... and the pump is finally off.

ugh.

I'm not a fisherman but I feel like I've landed a very fat fish.

(apologies as this post doesn't add any new or useful information... but it does let me vent!)

jgra1 · Post by **jgra1** » 27 Jul 2010, 11:10

yep sorry Romie, we've all been there ..

banana/crescent spanners (or just a 13mm one) are a must for a TD owner

I think my draper set was only a £10 and has various sizes in..

John

romie · Post by **romie** » 29 Jul 2010, 15:25

SOLVED!!!

ok, so that injector pump WAS faulty.

Having removed and stripped the pump on the bench I found that both plunger-return springs had broken, (interestingly both had two breaks in the same locations).

So if anyone shows a video of a 'weak' output like this one, this 'could' be a possible place to look.

Bosch said it WAS a serviceable part and so I should have the plunger spring 'kit', (wonder what could be in the 'kit' apart from, er, two springs?), arriving in a few days time at a cost of around £10.

They also suggested that they would need to calibrate the pump after I fitted the springs. The only thing that I figured that could change would be the strength of the springs which by the looks of their operation wouldn't change the pumps operation very much so I cheerfully declined their pricey offer in favour of 'we'll see how it goes'.

Here are some pictures of the dismantle and broken plunger-return springs.

>>>>>> BROKEN PLUNGER-RETURN SPRINGS <<<<<<<<

Many thanks to everyone for all your advice with this, I'll put up a video of what a healthy Citroen Xantia 1.9TD Estate 1996 Bosch distributor injection pumps output should look like after I've re-fitted everything and proved that it runs.

Cheers again

davetherave · Post by **davetherave** » 29 Jul 2010, 15:29

Nice one, always feels good to solve a problem like that, and its also good that there are a few people who bother to do so!
For many with a similar problem i guess it would be new car time!

Post by **myglaren** » 29 Jul 2010, 15:40

davetherave wrote:Nice one, always feels good to solve a problem like that, and its also good that there are a few people who bother to do so!
For many with a similar problem i guess it would be new car time!

It would in view of the common assumption* that the pumps are not repairable and that a replacement costs in the region of £1,000 and has to be fitted by a dealer and coded to the engine.

*I wonder who spreads these rumours? Dealers, very possibly!

romie · Post by **romie** » 29 Jul 2010, 15:41

I bought the car for £420 and my day job is as an embedded system engineer - not vehicle technician - so it would have been, 'time to replace car' had it not been for you guys and my, frugalisanty, stubbornness and curiosity for the unknown.

I'd definitely recommend people to take this sort of job on seeing as the cost of repair/replacement would normally mean the demise of a perfectly good vehicle.

I'm wondering if the springs could be replaced with pump in situ? Don't think so as the pump needs to be held with distributor end upright to stop all the plunger mechanism from dropping out.. hmm, am sure someone's going to achieve it at some point - never say something can't be done eh