Diesel puddle in inlet manifold

Apologies straight away if I'm done anything incorrectly, or not completed something I should have, as per joining the forum as a new member.
My query, if anyone can help: I have a 1987 90 turbo diesel with 19J engine which has been parked up for about four years. After changes of fluids and filters etc it is now starting and ticking over happily, more or less smoke free. Increasing revs however results in an engine run away (if that's the right expression) ie starts revving ++ with smoke++ Fortunately stops straight away when the fuel cut off on the injection pump is disconnected / ignition switch turned off.
The throttle cable isn't sticking. There is no sign of oil in coolant and no steam escaping from rocker box / breather as per head oil leaks etc. Sump oil level correct and oil drains OK into sump from turbo. Turbo does not have undue wear or signs of oil leaks so I don't think the engine is over-running on engine oil.
Today I took off the inlet manifold and found that it had a puddle of diesel inside so I presume it starts injesting such at increased engine revs initiating the run away.
What is the most likely cause of a diesel puddle in the inlet manifold ??
(I'm a DIY mechanic so operating from a fairly restricted knowledge base esp with regard to diesels)

Car-pet said:

Apologies straight away if I'm done anything incorrectly, or not completed something I should have, as per joining the forum as a new member.
My query, if anyone can help: I have a 1987 90 turbo diesel with 19J engine which has been parked up for about four years. After changes of fluids and filters etc it is now starting and ticking over happily, more or less smoke free. Increasing revs however results in an engine run away (if that's the right expression) ie starts revving ++ with smoke++ Fortunately stops straight away when the fuel cut off on the injection pump is disconnected / ignition switch turned off.
The throttle cable isn't sticking. There is no sign of oil in coolant and no steam escaping from rocker box / breather as per head oil leaks etc. Sump oil level correct and oil drains OK into sump from turbo. Turbo does not have undue wear or signs of oil leaks so I don't think the engine is over-running on engine oil.
Today I took off the inlet manifold and found that it had a puddle of diesel inside so I presume it starts injesting such at increased engine revs initiating the run away.
What is the most likely cause of a diesel puddle in the inlet manifold ??
(I'm a DIY mechanic so operating from a fairly restricted knowledge base esp with regard to diesels)

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Welcome to LZ!

I think the cause of your issue is a failed diaphragm in the fuel injection pump, which is allowing fuel to be sucked up the pipe into the turbocharger, and into the engine, causing the fuel in the manifold, and the runaways.

I suggest getting the issue sorted before using the vehicle again. If the little runaways turn into a big runaway, it will destroy your engine.

ie probably need to take off injector pump and get checked or replaced ?
(agreed not to run / blow up engine !! )
(not on road in any case)

Car-pet said:

ie probably need to take off injector pump and get checked or replaced ?
(agreed not to run / blow up engine !! )
(not on road in any case)

Click to expand...

As a temporary fix, you could replace the diaphragm yourself. It is in a housing on the underside of the DPS pump, so access is limited. It is a fiddly job.

I doubt if that will work for all that long, so in the longer term, as you say, pump off and take to a specialist.
Not a bad job if you have a pump holding tool, or want to change the drivebelt anyway.

You can test the theory by pulling the little plastic pipe out of the connector at the turbocharger end, and running the engine.
If fuel emerges from the pipe, the diaphragm has failed.

That all makes sense - was thinking fuel pump issues - I'll get on with that over next day or two.
Thanks for an amazingly quick response.
Will post back re outcome in due course.
Thanks again - really helpful

Car-pet said:

That all makes sense - was thinking fuel pump issues - I'll get on with that over next day or two.
Thanks for an amazingly quick response.
Will post back re outcome in due course.
Thanks again - really helpful

Click to expand...

No worries.

There is indeed fuel coming out of the vacuum pipe as suggested.
Will have a go at replacing the diaphragm as doesn't look too impossible and worth a try.