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You probably have to prime by pushing the plunger up and down on the filter housing until it becomes stiffer.
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Fuel ?
- Thread starter froggy Steve
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Towpack
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When I pull onto the drive facing uphill, probably around 1 in 10-12 slope, the idle speed drops noticeably. Also, when starting, it doesn't fire instantly as normal but spins over a few revs, unless I touch the throttle slightly. None of this happens when facing downhill. I've never noticed any power loss on the move though and EGT's can still max out under heavy load so I don't think there's any restriction in fuel delivery as such.
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It was easier to let the walbro pump do it for me
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Dave in Spain said something about a spring in the pump could be broken if it does that....Dave2000?
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This can be a sign the diaphragm in the hand primer is showing early signs of failing.
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If the pump clicks the design is probo like the SU petrol pumps. They have points which get dirty and they always pack up. A smart tap with something usually gates them going. Cleaning the points gets it back like new.
Mine started this about a year after owning it, exactly the same symptoms in fact , if you watch your idle when stationary and level and then roll downhill in neutral and gently apply the brake you may find your idle goes up a few RPM?
So I checked everything....and I mean everything, including pumping the primer with the car pointing uphill, RPM did not change, even tried a pipe from one of the Jerry cans on my roof rack, so car pointing uphill but fuel being fed via gravity, still no joy.
Went to the diesel shop and he knew what it was straight away, apparently trying to understand his Spanish, there is a small spring that is on or near the governor? He said it is probably weak or broken, apparently responsible for keeping the governor or something near it central? He said turn up the RPM a little to overcome any effect on daily driving and it will be fine for many years to come, or cross his palm with mucho dinereo and my first born to rebuild the pump. That was nine years ago, still going strong!
An added bonus is when rolling along in a line of traffic the engine does not surge up and down when the AC kicks in/out, the perfect idle speed matches the idle up for the AC, as mentioned nine years, no issues.
Re the pusher pump, it most definitely is not needed if all is good on the stock system however, if there is a tiny hole in the primer diaphragm or anywhere along the hose from the tank to the pump inlet and of course if the lift pump inside the fuel pump is not 'pulling' correctly then the electric 'pusher' will hide that problem, I did in fact try a pusher pump when investigating the pointing uphill slower idle issue, it made no difference whatsoever, it was removed.
@froggy Steve Re the woodpecker, check the exhaust mounts, normally the first one after the turbo, it runs near the step and makes odd noises when worn, often accompanied by a soft 'thunk' when you switch off the engine. Seems you have the issues under control, well done.
regards
Dave
Towpack
Well-Known Member
My idle speed on the flat is around 600-650rpm rising to around 800 when the AC kicks in or when turning and activating the PS idle up mechanism. I could probably set the idle up a tad lower but, mine being a manual, the varying idle speed due to AC And PS isn't really a problem TBH. In fact, the idle drop when facing up hill isn't really a problem in itself, more an observation. It's certainly not bad enough to warrant the time, effort and £££ of a pump removal and rebuild!
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If a pump is fitted to overcome a pinhole or leak in the supply side presumably a diesel leak will occur at that point?
You would think that Frank but we are talking about a tiny pin hole, if the hole is small enough air gets drawn in and collects in tiny bubbles normally at the top of the diaphragm, they then collect to be one big bubble and then gets shoved/sucked through the pump and you get a misfire for a second or two, and this repeats itself.
Assuming we now add an electric pump it is only running when the engine is, then the amount of pressure applied to our pinhole is is minimal, with the engine pump sucking and the pump pushing say 5 or 6 psi it might equal out a little and be perhaps 3 or 4 psi? Certainly not enough to make a puddle, and of course if it is up under the chassis somewhere it might not get noticed, of course when the engine is stopped the electric pump also stops. Now we have a reverse scenario, the pinhole now 'sees' a negative as the fuel is drawn back to the tank, this is why a lot of diesels run perfect all day after having taken an hour to get started.
So the one little pinhole can cause a whole host of problems.
regards
Dave
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Both the idle and AC speeds can be matched within a few minutes, mine too is manual and if you were idling in say first following a line of traffic the AC bring the idle up to 800 will give a jerky ride, I do recall a member complaining about this? I have my idle IIRC around 700...ish, when the AC kicks in the engine note barely changes, and of course the ride if idling in first remains constant.
You are right about whether spending money is worth it or not, as I said IMO it is not. Strange how long this is taking to surface on the 80, when I posted up on various forums nine...ish years ago no one had heard about it, now you are the fourth or fifth in the last six months or so to mention it. I don't even think about it now TBH.
regards
Dave
