JP3 won't start from cold (used to be just fine)

[Proper Job]

I'd certainly give the decompression wheels a good oil and screw them in and out several times as tightly as possible,

 

 

 

IIRC the JP handbook says that the decomression threads should be rust free and kept clear of oil and grease

[Sir Nibble]

Any update? Updates are not only good for the curious amongst us, but others who have a similar fault in the future will no doubt do a search and stumble across this thread.

Sorry to say this but I frequently see problems posted for which I know the solution but unless it's for an established member I don't bother to post it because....

1. It's too much trouble shouting down alternatives from amateurs who have read a book

2. We usually get no feedback and I'm not here to be used and rudely ignored.

[sassan]

Problem still ongoing.

Have checked valve clearances.

Am rigging up an alternative fuel supply (jerry can, piping, filter) to rule out low quality fuel and inadequate fuel pressure to injector pump, hopefully tonight or tomorrow. Will report back on how it goes.

[Tony Brooks]

Re the Easystart question.

 

It all depends upon how you use it, especially on a diesel. If you squirt it into the intake of a stationary engine or keep on squirting it on a spinning engine you may well cause premature combustion with the piston still going up. This causes a massive pressure rise that can snap rings or break the land son the piston (let alone doing goodness knows what to other parts as the piston tries to stop dead). So just once could be enough to cause problems.

 

It is also likely to wash oil from the piston walls that can lead to premature wear, however if it is used sparingly, into a spinning engine and only occasionally I doubt you would ever notice the accelerated wear.

 

The main question

 

I can not see where the OP describes the degree of smoke from the exhaust whilst cranking. If its only a few wisps I go with the majority and would be looking at re-bleeding. If its lots then there is another fault, possible like compression, timing or faulty injectors.

[RLWP]

Sorry to say this but I frequently see problems posted for which I know the solution but unless it's for an established member I don't bother to post it because....1. It's too much trouble shouting down alternatives from amateurs who have read a book2. We usually get no feedback and I'm not here to be used and rudely ignored.

I read a book once, it was green

 

Richard

[by'eck]

 

IIRC the JP handbook says that the decomression threads should be rust free and kept clear of oil and grease

 

Keep the screw thread clean and bright are the actual words. I also keep mine lightly oiled.

[frangar]

Keep the screw thread clean and bright are the actual words. I also keep mine lightly oiled.

Ditto....and I use mine often as well

 

Cheers

 

Gareth

[George94]

 

IIRC the JP handbook says that the decomression threads should be rust free and kept clear of oil and grease

 

It says: "Keep the screw thread clean and bright".

 

I wouldn't advocate using grease, but it's difficult to keep bare metal clean and bright without a little oil.

 

ETA: Whoops, others have beaten me to it.

Edited April 23, 2014 by George94

[bizzard]

I'd be inclined to use traditional Redex upper cylinder lubricant, formulated to break down and dissolve carbon, and it does.

[Timleech]

I'd be inclined to use traditional Redex upper cylinder lubricant, formulated to break down and dissolve carbon, and it does.

Have you tried to buy it lately? There seem to be umpteen Redex branded wonder products, but none whose label suggests direct equivalence that I have found. Maybe it's out there somewhere, or sold as something fancier??

 

Tim

[bizzard]

Have you tried to buy it lately? There seem to be umpteen Redex branded wonder products, but none whose label suggests direct equivalence that I have found. Maybe it's out there somewhere, or sold as something fancier??

 

Tim

I do sometimes buy the small plastic bottles of Redex for petrol engines which I use in my car which has a carburetter which doesn't like unleaded petrol and it certainly keeps it clean as I got fed up with keep cleaning the idle jet, not carbon of course though but residue.. And I decoked an old Briggs and Stratton sit on lawn mower engine a short while ago and I did what I used to do years ago when decoking engines was a regular buisness, and that was to squirt a drop of the same Redex onto the piston crown instead of scraping it to remove carbon, left it over night and just wiped off the dissolved carbon next day, so it did still dissolve carbon, it worked on the lawn mower engine anyway.

[sassan]

FIXED!! Many thanks to Martyn!

 

Turns out the pump timing had slipped. All back to normal now!

 

The last couple of months have certainly been educational!

 

Thanks to everyone who's offered help and advice!

Edited May 22, 2014 by sassan

[martyn 1]

To finish off the thread for people in the future that may suffer the same issue.

 

Engine had only done in the region of 200 hours since a bare block rebuild so was unlikely to be much wrong. The engine was found as below.

 

1, Very good compression on all cylinders.

2. Valve clearances correct.

3. Fuel system was fully bled and when turning by hand a good creek was easily heard from all injectors.

 

So should easily start, but even with the overload pawl in the cold start position and change over valves in high the engine cranks over with no hint of firing. Looking at the exhaust the engine is doing a good 10+ revolutions before any signs of smoke from the exhaust which hints at very incorrect injection timing. based on all other things checking out ok.

 

Further investigation found that the fasteners on the adjustable coupling between the injector pump and engine were loose and the adjuster had slipped fully in one direction.

 

4. Checked the spill point timing to find that without moving the coupling from its slipped position it was injecting about 1 Degree before TDC.

5. Readjusted to the correct 26 Degrees before TDC.

6. And voila started within about 1 turn.