early 2.5 NA 90 injector pump cold start problem

This is a 1985 SWB 90 NA

Bit of background. Engine is currently ex MOD and in good condition. Starts off key cold in 10 seconds, bought to swap out the old engine which was worn out. Guy I bought it off said engine was said good but in fact when dropped in ran like a dog – swapped the injector pump from my old engine as was best bit left as assumed it was pump making it run lousy but still same – turned out that head gasket was blown in couple of places. Head skimmed, new gasket etc. all fine.

After six months old injector pump starts leaking diesel everywhere so decide to use pump that came with MOD engine that I had taken off. Had it checked out by diesel specialist to see if it did what it was supposed to do all checked out OK.

Fitted it, bled it through and fired up – started well but then revved like a lunatic, went to switch off on the key and it would not stop - so in gear and stalled it. Checked stop solenoid on pump – plenty of clicking so assumed OK. Started up again, revved up but not so much and then quickly settled down – drove it out and ran really well, stopped on the key no problem. Parked it up and next morning went to hitch up trailer and started fine, ran for four seconds and just stopped like I had turned it off on the key – gave it some more heat and tried again. Started after 10 seconds of turning and cut out again and would not go. Felt like fuel starvation.

Dismantled all the fuel lines as it’s an old one – 1985, so expected there to be some gunk somewhere, was all clear. It’s got a new lift pump on and all. Bled through again and fired up fine only to cut out. Can't find any broken lines/leaks and injectors are refurb. No blue smoke so no it's not eating it's own oil - plenty of black smoke though when it charges of into the distance. Fine when it's warm, no smoke at all.

Now when I start it as soon as it fires I rev the nuts off it to keep it going and eight times out of ten it will rev hard it’s self and then I just bung it into gear and hang on – as soon as I get to the top of the track it’s ticking over like nothing had ever happened as if it says what was the fuss all about? Then when it’s warmed up a bit, when I take off, and if I don’t load the throttle too much it will pull fine, nice and gentle and then all of a sudden it takes on a life of it’s own, clears it’s throat and pulls like a bloody train which would be good if I wanted it to but it’s now a bloody pain and I haven’t got the foggiest what is going on – anyone got any ideas?

having pump checked is no guarrentee it will perform at idle /start ,ive had it several times, id check injectors too

Before I bought my 90 yonks ago it did this, my friend who I bought it from stripped it and found the pump to be gummed up something chronic.

A good clean and it was sorted - he also took it to Lucas and got them to re-calibrate it.

I could possibly sell you it - it only did 20,000 before I took the NA out for a 300tdi.

Thanks for the useful input - I had not considered the possibility that the thing could be gummed up - I think what I would like to try is a cleaner/additive and see if this helps but the offer of a good pump is very tempting as it's a bugger to drive, thank you. How do folks here go about doing deals with each other?

cheers.

Depends - paypal I guess.

I've sent you a PM but here is my latest information as I have re-read your original post and want to make a few more suggestions first.

I have been through these woes with a 2.5NA and even did some of the things you did also to no avail I knew the answer all along and in the end it was air. Had I just spent £25 on all new fittings and pipe I would have got it to work at the time but I was secretly looking for an excuse to fit a 300tdi.

Anyway, a few things to check first, sorry if you have already done these.

The Lucas pump cannot bleed any air out of itself, air will lead it to doing things exactly as you suggested, except the fast idle and having to stall it - odd. Therefore the Lucas pump must always be connected to the Lucas CAV fuel filter assembly or one that offers the same characteristics; that is to purge air from the fuel stream before it is fed into the injection pump (which should be at the BACK of this pump next to the injection lines).

To make sure the filter head is allowing air to be purged from the fuel stream you need to remove bolt from the banjo connection on top of the filter. This should split into 4 parts: two copper washers, one top one bottom, the banjo still connected to the bleed line and the banjo bolt. Look at the banjo bolt and you will see a very small hole, this is the air escape hole, it is very small so that it will allow LOTS of air to escape but very little diesel. Ensure it is clean, and air can pass through it: you can poke it with a strand of wire to clean it out.

Reassemble the filter but before doing so anneal the copper washers, very simple, using a small blow lamp or the gas stove or even one of these storm-proof jet lighters, heat the copper up until it glows cherry red then plunge into a bath of cold water or leave to cool naturally. This will soften the washer up and allow it to reseal well. You can also cross hatch it on a fine metal file then rub a very thin smear of hylomar or hermatite over it, allow to tack up then install. Make sure the surfaces are all diesel free and very clean and that the surfaces of the banjo, filter head and bolt are all smooth and defect free.

Now disconnect the OUTLET from the filter head (check it is an outlet arrow on it) which leads to the back of your injection pump.

Clean up the union, check the olive and wrap the olive in PTFE tape (plumbers tape), a good 15 or 20 tight wraps. Insert into the filter head and tighten the union down.

Now clean the area surrounding the union on the injector pump and remove it, similar practises to above, clean it all up and rebuild it ensuring it is sealed up perfectly.

Now do the same for the return pipe, although it is the return it can be a cause of air ingress when the engine is off so do both ends of this pipe (pump and filter head).

Now same again, lift pump unions.

That should be all the important connections checked and resealed.

Now I would do this for the purposes of testing and it’s up to you, but disconnect the feed from the fuel tank to the lift pump, get a piece of pipe and run a pipe fed directly from a clear bottle of clean diesel into the lift pump.

Now prime the system, I am sure you're well versed at this having changed the pump round.

This whole job might take you an hour or something, but you will kick yourself if you spend more money and time on a new pump to find that your engine still runs poorly.

Once sure the whole system is sealed up, give her a whirl and see what happens – might be a good idea to tape the diesel bottle in somewhere so you can drive it.

Also, what sort of fuel pipe do you have? Nylon with olives and inserts? Or rubber hose and and hose barbs?

That's a pretty comprehensive list - brilliant. I have just come back in and found that the small hole you refer to was blocked up with a fairly large chunk of wood fibre and took some forcing back into the main drilling - checked through everything else you mentioned and will have to wait now until it's cold as I have been running around in it all day - I started it up and that was fine after all the checks so fingers crossed, will report back in the morning after a normal start up and take her for a whirl - which will be the acid test, nice advice - thanks for that. Forgot to mention - fuel lines are plastic (nylon?) with olives, all original I think as it's a one owner vehicle and I know the chap I bought it off and he never did anything to it - left that all for me

FIXED!

And all it was was a blocked bleed airway, how simple was that? - brilliant advice and I would never have know if it wasn't for the heads up.

Cheers for getting me going again.

No bother...

Damn, I could have sold you an injection pump!

Ha, your reward will be in heaven.....unless you have a double rear step kicking around that you fancy selling