Lister JP3 timing problem.

[Ianbruce]

Hi Martin, conducted a pressure test on the JP3 this morning and could only manage 200psi for each cylinder (600 to start 450 to run) which is way too low. Verdict being the starter motor is turning too slow. An electrical test saw 13v from fully charged battery dropping to 8v when starter engaged indicating a fault with the starter. I can rig up a temporary fuel supply with fresh fuel tomorrow and see if it will fire before stripping out the starter motor. Ive been told of a shop in Victoria Rd Leicester called Greens who can recondition the  motor..

Edited June 5, 2020 by Ianbruce

[WotEver]

1 hour ago, Ianbruce said:

An electrical test saw 13v from fully charged battery dropping to 8v when starter engaged indicating a fault with the starter.

Are you absolutely sure that it's not a poor connection twixt battery and starter motor? Those symptoms are classic for a dodgy isolator switch or similar. Was it dropping to 8V at the battery or at the starter?

 

Of course, it could be the starter, but best to check the easy stuff first.

[Tony Brooks]

Absolutely correct although I did read it as being at the battery. Tthat is the danger of assumption when we are not told.

[David Mack]

You appear to have a hand start fitted to your engine. Have you tried It? It shouldn't be that hard to hand start in this weather.

[Tracy D'arth]

That's a worrying low compression. Have you tried a teaspoon full of oil in each cylinder first?

Was this test done with the other 2 cylinders  decompressed by removing all 3 injectors? 

[martyn 1]

Sorry for the late response wading back in. Ive been away playing with JP2's and Samofa's.

 

So from you last response about the firing, if it is firing equally on all cylinders and reasonably well e.g. running away from the starter momenterily and lots of black smoke then you can rule out anything that effects only one cylinder. so that rules out the individual elements, delivery valves, injectors.

 

And although your compression reading is pitifully low that is not surprising as A. If you have a starter issue and the other cylinder are still compressed or the starter is really struggling you wont spin it fast enough to get a sensible reading and B. the 600psi in the manual for starting compression is for an engine that has been running and then compression tested so up to temp not one that hasn't run in years and is cold in comparison so that doesnt surprise me. If you have enough compression to fire when turned over then that isnt the issue, even with very worn out pistons/liners/rings in the temps we have been seeing recently it will still go, although may be a bit more of a pain to get there.  If your getting it fire and black smoke then it isnt compression because if it was sufficiently low enough to stop it running it wouldnt fire at all/very little and the smoke would be grey.

 

So I would be checking now. (on the assumption that you are certain the valve clearances are set correctly. that when cranked with only one cylinder at a time compressed it is firing and has black smoke and that the level of attempt to fire is equal accross all the cylinder)

 

1. Check that you have good fuel pressure at the pump. (with a delivery valve removed and nut refitted, pump rack at full fuel position and anywhere in an engine rotation other than at the spill point (if you dont get fuel at first turn the crank 1/4 to 1/2 a turn and it should start flowing). Fuel should flow from the port and provide a jet up from the pump of about 2 inches at a minimum. any less than this and you have low fuel pressure. So if that is the case check for blocked filters/blockages in general and closed/partially closed valves...... once you are certain you have decent fuel pressure then move on.

 

2. Make sure the spill timing is spot on. If you want me to talk you though this whilst your stood next to the engine then give me a call. you will need a spill pipe not just an open port on the pump to get this correct.

 

3. Not likely a cause unless its sticking near the no fuel position but I would check anyway to rule it out. Ensure the govenor rod within the engine (end of the rod about 9/16" dia has a spring around it before contacting with the bell crank is free to move and that also applies to the bell crank (throttle arm) make sure it moves with no tight spots.

 

4. Try starting it. pump rack at full fuel. in high compression. decompressed at first and drop each cylinder in one at a time as if you were hand starting it. this will allow the starter to spin it to a greater speed that when trying to drag all three compressed cylinders around

 

 

 

Edited June 5, 2020 by martyn 1

[Ianbruce]

Wotever: battery connections checked, earth checked. Voltage taken at starter motor.

David: I dont have a handle. Intended to get one but never got around to it. As never needed before.

Martin: I am going to try to start the engine with fresh fuel from a temporary supply and will go through your list when I bleed it through. I have timed at spill using the injector pipe. I know for a fact it used to run happily with the timing all over the place. I have a video off U tube exactly how to do it. We have tried spinning her up while decompressed and trying each cylinder in turn. 

The governor only pushes on the throttle lever which is currently disconected as the brass bar to the rack was found to be too long not allowing full throttle. It is all moving freely I freed it off .  However it has always started as it was. 

My wife was rushed to hospital tonight so it may take a few days before I get back to you

[WotEver]

1 hour ago, Ianbruce said:

Wotever: battery connections checked, earth checked. Voltage taken at starter motor.

Please check it at the battery when you can. 

 

1 hour ago, Ianbruce said:

My wife was rushed to hospital tonight so it may take a few days before I get back to you

My very best wishes. I hope it’s nothing too serious. 

[Ianbruce]

Thanks but it was close ...Mrs G had full blown heart attack 3 stents later shes back home. I will try fresh fuel tomorrow, fingers crossed. If no joy go through everything again if still no joy Ill take the starter motor to be tested. That will be fun bet it hasnt been out the case/ holder since 1959

[Ianbruce]

Fresh fuel made no diference. Starter taken to specialist and found to be in perfect working order. All connections cleaned back to battery. Will try it again tomorrow may just jump starter straight to battery. Having gone through all the advice from the start again. It's got to be something simple some where but what. 

[Ianbruce]

Fresh fuel made no diference. Starter taken to specialist and found to be in perfect working order. All connections cleaned back to battery. Will try it again tomorrow may just jump starter straight to battery. Having gone through all the advice from the start again. It's got to be something simple some where but what. 

[Ianbruce]

She STARTED! On the Starter she got faster and faster until she finally picked up and ran. It was the starter..duff connections/ dirty armature with the fresh fuel just needed that tiny bit extra to fire up. Initially filled the sky with smoke but then ran clear even in gear. Thanks for all your advice. 

What's the thoughts on glow plugs for a JP engine. They fit in the Hi/Lo compression valves giving a compression halfway between the two settings. Also Red or Green fly wheel. 

Martin in the photo of the grey engine you sent there is a brass drain tap in the block plug hole can you tell me what size and thread that would be

Cheers Ian 

[Tracy D'arth]

Rather than glow plugs, try a blowlamp into the air intake whilst cranking, my old concrete mixer always needed this.

TD'

 

 

 

Edited June 15, 2020 by Tracy D'arth

[David Mack]

3 hours ago, Ianbruce said:

Also Red or Green fly wheel

It won't make much difference to how easily it starts.

?

[WotEver]

12 hours ago, Ianbruce said:

It was the starter..duff connections/ dirty armature with the fresh fuel just needed that tiny bit extra to fire up.

It was a poor connection twixt battery and starter motor. Either the main feed or the -ve return.  The 8V at the starter was the dead giveaway.