PH1 engine prime lever / non start

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PH1 engine prime lever / non start

Post #1 by Cheekymonkey » Wed Jul 26, 2017 9:28 am

Added as new post as suggested.
========
Hi All,

I lent my thwaites nimbus to my builders today, perhaps a mistake. Never had an issue with her & they broke her in an hour.

She has PH1 engine.

They say she ran out of fuel. They then went through various ways of trying to restart it after filling by bumping starting it behind their van, then bled the fuel line, then played with the primer lever. I 'THINK' they may have tried to turn over & force something with the prime lever possible breaking the mechanisum or worse

In my tests so far I have ascertained that there is not fuel at the injector (i took the line off & turned if over & nothing)
When bleeding there IS fuel down at the rack on the bleed screw
When using the prime lever it never feels like there is any compression at all it just flops up & down.

Is it possible they broke the mechanism?
I was planning on taking off the primer/pump to take a look at some point over the next day or so but if any other thoughts or tips just shout & I can do any tests.


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Re: PH1 engine prime lever / non start

Post #2 by mechman » Wed Jul 26, 2017 11:41 am

Could the fuel pump be stuck in the injection position or maybe the spring in the top of the pump is broken.

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Re: PH1 engine prime lever / non start

Post #3 by FOWLER MAN » Wed Jul 26, 2017 8:39 pm

Hi,
Have you turned the engine so that the camshaft is not lifting the pump plunger.
If the cam has lifted the plunger the priming lever will not operate the pump and there will be no resistance to the lever when you use it. Turn the engine quietly till you feel the resistance at the primer lever.
You can also bleed the system by undoing the top of the injector pipe and just turning the decompressed engine over a few times till the fuel appears.
Alternatively the pump plunger may be stuck at the top of its stroke.

Fred


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Re: PH1 engine prime lever / non start

Post #4 by essexpete » Wed Jul 26, 2017 11:58 pm

The nimbus has the tank quite high. In the past I have wiped the filler and pressurised the tank with a good puff (don't blow your own gasket!)


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Re: PH1 engine prime lever / non start

Post #5 by Cheekymonkey » Thu Jul 27, 2017 11:48 am

some useful things to try this weekend. great help as always


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Re: PH1 engine prime lever / non start

Post #6 by mechman » Sun Jul 30, 2017 7:07 pm

Did you get the PH1 sorted?


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Re: PH1 engine prime lever / non start

Post #7 by Cheekymonkey » Wed Aug 02, 2017 8:23 am

mechman wrote:Did you get the PH1 sorted?


Hi Mechman actually no still not yet. I tried to turn engine to find the cam for the primer but still dont get any pressure. Still no fuel at injector.

Life is total chaos at the moment with a fairly major build onour house so it's been sat there sadly. The builders have offered to pay for someone to solve it & there's an agricultural engineer in the village who said he can take a look. Feels to me something is broken in the prime/pump mechanisum.

I'll update here when know the issue :)


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Re: PH1 engine prime lever / non start

Post #8 by Cheekymonkey » Mon Aug 07, 2017 8:18 am

Hi All,

So had a local agricultural engineer over & he couldn't get her started either.

He thinks the Bryce pump is shot. I have taken it off & the rack is a bit loose nut nothing else obvious. Top spring intact. Bottom still moves when pressed firmly

When moving the rack back & forth should the internals also move back & forth (not sure what it's called but there is a cylinder inside the housing that spins) as mine sometimes turns back & forth but sometimes keeps turnings, stops & turns again when moving rack. I wonder if the rack is gone.

Struggling to find a new pump for anywhere near sensible money. I found a repair kit but can't work out how to strip the remaining parts off.

Any advice or sources for pumps? Seems like some indian ones on ebay but not sure if any good.

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Re: PH1 engine prime lever / non start

Post #9 by FOWLER MAN » Tue Aug 08, 2017 11:51 am

HI,
The rack will be loose on a well used pump so that's nothing to worry about, it should move back and fore with the lightest of finger pressure.
If I understand you rightly, now that you have removed the pump you require considerable pressure to push in the plunger at the bottom of the pump so the spring must be OK.
That being the case if you have turned the engine over and still can't feel resistance on the priming lever there must be a fault with the rocker which operates the pump.
The pump is driven from the cam shaft by a rocker like a valve rocker with an adjusting screw to set the pump timing. Is there something broken there or has the lock bolt and adjuster screw become loose and backed off?? That would have the same effect though I have never seen that happen.
You have only to remove the four bolts and side plate on the pump mounting casting to check this out.

When you say the top spring is OK I take it you mean the delivery valve spring under the fitting that the injector pipe connects to? Have you checked that the delivery valve plunger which is under the spring is free as the pump will nor inject if it is stuck?
If you remove the spring and plunger and turn the engine to about a quarter of a turn before TDC there should be a constant flow of fuel through the pump.
Let us know what you find and I will talk you through setting the pump timing if it has been disturbed.

Good luck.
Fred


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Re: PH1 engine prime lever / non start

Post #10 by Cheekymonkey » Tue Aug 08, 2017 12:01 pm

FOWLER MAN wrote:HI,
The rack will be loose on a well used pump so that's nothing to worry about, it should move back and fore with the lightest of finger pressure.
If I understand you rightly, now that you have removed the pump you require considerable pressure to push in the plunger at the bottom of the pump so the spring must be OK.
That being the case if you have turned the engine over and still can't feel resistance on the priming lever there must be a fault with the rocker which operates the pump.
The pump is driven from the cam shaft by a rocker like a valve rocker with an adjusting screw to set the pump timing. Is there something broken there or has the lock bolt and adjuster screw become loose and backed off?? That would have the same effect though I have never seen that happen.
You have only to remove the four bolts and side plate on the pump mounting casting to check this out.

When you say the top spring is OK I take it you mean the delivery valve spring under the fitting that the injector pipe connects to. Have you checked that the delivery valve plunger which is under the spring is free as the pump will nor inject if it is stuck.
If you remove the spring and plunger and turn the engine to about a quarter of a turn before TDC there should be a constant flow of fuel through the pump.
Let us know what you find and II will talk you through setting the pump timing if it has been disturbed.

Good luck.
Fred


Thanks Fred, yes some more detail below:

- Bottom spring = ok
- Priming cam = operating ok when turning over you see the piston go up & down so seems ok (took cover off & nothing broken it seems)
- delivery valve spring = ok & the small part (i guess the plunger if thats what it was is ok & fell out when i stripped down (it's like a small cross head screwdriver bit)

Can nolonger find TDC mark on the flywheel & also pump is not fitted any more to test that.

Basically the rack doesn't feel quite right & any slight twist when manually moving it back & forth it sticks & sometimes the internals of the pump spin & sometimes not. I wonder if some teeth worn or some crap stopping it move properly. Cant work out how to get rack off & the internals out, there is some kind of circlip in the bottom but has no ears to use pliers. Seems like a new pumps is £130 ish :(


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