Slack in bosch pump?

[dt_]

Hi guys, just purchased a 405 Estate, 1.9d family wagon, and am having a bit of trouble with the bosch injection pump.

Basically, the first quarter of the throttle travel does nothing.  I have adjusted the cable to take up this slack, so the pedal is responsive, but as a result I can only get 3/4 throttle, and the throttle arm does not reach its rest, its suspended 'open' on the cable.  Is this a common problem with these pumps?  Never had any trouble with the one on my zx (bosch, turbo) 

If so, is it a case of removing the throttle arm, rotating it back, and then refitting, or is this compensating for some kind of internal wear? With it being a nad estate car, I could use that extra quarter throttle!

And help or advice appreciated

[dt_]

Well, for anyone reading or interested, I ended up removing the control lever and re indexing it a 'notch' back, which cured the dead travel, but the car still seemed to be holding back, even for a nad.

I then took a closer look at the pump and looked specifically at the fuel (smoke) screw. The collar was loose, and the yellow paint was missing from the locknut. Normally I would have expected someone to attempt to 'tune it up' a little by screwing it in, but the collar was present and slack on the screw thread, and that got me thinking, maybe someone screwed it out??

Gave it a half turn clockwise, and the grunt is restored, it feels almost sprightly and has good pull from less than 1000 rpm. Was still scratching my head as to why someone would 'detune' an already slow car like that. Further reading into the MOT history indicated a smoke test failure about 6 years ago; some scrote mechanic probably thought this was an easier way to get it through a test, instead of giving it a thrash, changing fuel/air filters, checking that its actually diesel in the tank and not tar/chip fat/old gearbox oil (delete as appropriate)

Tldr: car sorted, it was 'detuned'

[dt_]

Here's the old fuel filter.  What do you reckon this motors been running on?

Pic not working, but it was really brown and greasy, with lumps stuck to it

[Mighty306]

Posting photos via rhe site's upload facility is not straightforward I'm afraid. Took me a few attempts to get it.

Nice one for posting an update on this. Often we don't get to find out what happened.

[ekjdm14]

Hmm, missed this originally. In my experience running on veg oil (fresh at least) works well for the emissions test and our Xantia always flys through. You do go through a few fuel filters in the first few hundred miles because it cleans all the gunky residue out of the whole system too, only issues I've known it cause is blocked filters while it does it's thing (temporary inconvenience, just carry a few spares and a 4mm allen in the boot) & harder starting in winter (add up to 15% petrol or mix 50/50 veg/diesel) plus if you let them sit too long with SVO in the pump it can gum up pretty bad but then, so can modern diesel too. Again, in my experience.

brown/greasy and lumpy sounds like either badly filtered (not sub 1-micron) or wet waste veg oil, or possibly diesel bug infestation although without seeing it, hard to say & maybe just a really overdue filter job.

Glad it's sorted now, it's surprising how lazy and bodgy some "mechanics" can be. Strange thing is, it wouldn't even save them any time/effort as I Bet it would've passed fine after a good thrash and new air filter. Instead they spend probably longer and definitely much more fiddly time diddling with the pump...

The "real" bodge to pass the smoke test on a marginal engine is simply to back the throttle cable adjuster off until the engine only hits about 4000rpm. (maybe less maybe more, just as long as the tester can hear it to rev hard) Takes 30 seconds (a couple of minutes if you have to readjust a few times to get it right) and can be undone just as simply as moving the clip back to where it belongs).

[dt_]

Yeah the filter was really grim, I'll try and get a pic up soon when I get to my pc.   I agree with you regarding the mechanics effort, would have been far easier to slacken off the throttle, there's no rev counter on this car either so no evidence. 

Can't honestly say what it's been run on, on the drive home from purchase, I gave it some up a dual carriageway in third and it coaled like hell, then I passed a roundabout, did the same thing, same power but zero coal, and has not smoked since. 

Just rust issues to get on top of now, and then I've got a good, basic, comfy family car for a few years

[ekjdm14]

Tend to find they kick a lot of crap out the first flat out pull if they've been grannied around town a lot, guess the soot builds up in the system and doesn't get shoved out until it gets some revs/heat in the exhaust. Could it have been a shall we say less youthful previous owner? That'd possibly explain the emissions struggles in the past too if the tester neither knew nor cared how it was usually driven.

[dt_]

Nah it was a guy in his mid thirties, but I don't think he was using it much, if at all, and the fuel was well on the light.

Here's another observation-- the car does not slow down too well when you lift off the throttle. I was driving my zx today, and if you back off the gas suddenly, the car wants to nosedive and you'll be stopped in no time. The 405 slows really gradually. This could be normal, but I'd expect 2 1905cc diesel engines to slow down at a similar rate. Yeah the 405 is 150 or so kg heavier, but it also has a higher compression ratio and lower gear ratio so I'd expect them to slow at the same or similar rate. This being said, it's just bugging me a little, making me think it's something to do with the way the pump is set up. Zx pump is untouched, all factory paint and collars intact. Anti stall mechanism on 405 fuel pump is adjusted back as it was a little keen, making the engine rev when changing down gears from low revs. Idle is fine on both cars, nice and smooth and when revved at idle, the 405 takes a little longer to settle down to idle.

Its not undriveable at all, just an observation, making me think I may have altered something incorrectly, or is the zx just mega aggressive with fuel cutoff

[welshpug]

405 wont be that much heavier, pretty sure my mum's td estate was 1200 and my zx16v is 1150.

[Martin306]

Nah it was a guy in his mid thirties, but I don't think he was using it much, if at all, and the fuel was well on the light.

Here's another observation-- the car does not slow down too well when you lift off the throttle.  I was driving my zx today, and if you back off the gas suddenly, the car wants to nosedive and you'll be stopped in no time.  The 405 slows really gradually.  This could be normal, but I'd expect 2 1905cc diesel engines to slow down at a similar rate.  Yeah the 405 is 150 or so kg heavier, but it also has a higher compression ratio and lower gear ratio so I'd expect them to slow at the same or similar rate.  This being said, it's just bugging me a little, making me think it's something to do with the way the pump is set up.  Zx pump is untouched, all factory paint and collars intact.  Anti stall mechanism on 405 fuel pump is adjusted back as it was a little keen, making the engine rev when changing down gears from low revs.  Idle is fine on both cars, nice and smooth and when revved at idle, the 405 takes a little longer to settle down to idle.

Its not undriveable at all, just an observation, making me think I may have altered something incorrectly, or is the zx just mega aggressive with fuel cutoff

405's used to come with big dampers on the fuel pump, looks like a fat gear linkage. it slows the rate that the arm closes the throttle at.

if the ZX has one as well, it could be that it has failed. so it allows the throttle to snap shut.

[dt_]

The 405 has a little 'vacuum' capsule and spring loaded plunger to the rear of the pump, that is adjusted on a screw thread in a similar manner to the throttle rest stop or full throttle stop. I've adjusted this right back, it still stops the throttle snapping shut, but only just. The zx does indeed have a damper like a mini boot strut., and it's working as intended.

My musings are that as I have increased the fuel level, my reindexing of the throttle arm (I turned it further away from the pump to 'cure' some dead movement) is now holding a part of the pump open somewhere, or slowing its return to idle somewhat. The idle has increased very slightly since turning the fuel up. I've not gone mental with it mind, a max of 3/4 of a turn in total.

I'm wondering if all I needed was to turn the fuel up, and should have left the throttle lever where it was. Could it be possible that the fuel screw was turned out so much, that the first 1/4 of the throttle wasn't even injecting enough fuel to rev the engine?

Cheers for all the replies by the way

[ekjdm14]

Not 100% au-fait with the workings of the Bosch pumps (although suffice it to say I'm liking them very much more than Lucas at this current moment ! ) but I think you could be right the fuel screw could have been backed off too far. For the time it takes to move the arm and play with the screw it's got to be worth a shot anyway.

[dt_]

Hey well, thanks for all your help, just the other day I thought I'd clean out the rear wheel arches and check on a tiny rust patch, but it kept spreading to the point where its looking pretty rough near the rear beam mounts, and the inner sill on the drivers side is looking rough, so it's terminal I think. Probably a four figure labour sum there to set it all back right again instead of just a patchwork quilt job that will fail every winter. It's fixable, if you take your time I reckon, but it's not within my level of skill. Shame, just got it running sweetly aswell.

[Martin306]

Hey well, thanks for all your help, just the other day I thought I'd clean out the rear wheel arches and check on a tiny rust patch, but it kept spreading to the point where its looking pretty rough near the rear beam mounts, and the inner sill on the drivers side is looking rough, so it's terminal I think. Probably a four figure labour sum there to set it all back right again instead of just a patchwork quilt job that will fail every winter.  It's fixable, if you take your time I reckon, but it's not within my level of skill.  Shame, just got it running sweetly aswell.

Buy a good one with a broken engine, and swap the good one into it 

[dt_]

A knackered xud? Is there such a thing?