Do I need to do anything special when fitting a new diesel lift pump?

[coopec]

Or try the dreaded easy start in inlet filter to see if that ignites it. Do it with an injector pipe cracked to let air out but be ready to close it within a few secs. I have a feeling there's probably lots wrong with that idea.....

Your input to the forum is welcome!
OMG!
"easy start in inlet filter" You will destroy your engine, bend crankshafts and all that sort of thing!
Wash you mouth out!?

 

[coopec]

Thanks Paul.

It's silly, I know, but I'm nervous of cutting out a section of copper fuel line, to be replaced with two short sections of rubber hose.

But if it gets it going, it'll feel like I've won euromillions.

Anyway, I'm just off to seek out the nearest Halfords.

This may be a Workshop Manual for your motor.. "BMC Tempest 1.5 2.5"

If you look at the "Bleeding Fuel procedure" Page 60 of 115 it says to " Slacken the union nuts at the injector end of any two high pressure pipes"



https://www.marinedieselbasics.com/wp-content/uploads/BMC-Tempest-1-5-Manual.pdf

 

[NealB]

A (depressing) update.

After a successful start to yesterday (I set a new age-category record in our local Parkrun), it then went downhill.

I spent the afternoon trying to get the starboard engine running (yet again: VERY bored with this now).

I already had a 12 volt pump available (it's a supposed replica of a Range Rover fuel pump), so decided to try roughly installing it between the fuel tank and the primary filter (if it gets the engine running, I can happily tidy up later).

I used a pipe cutter, and cut out about half a metre of copper pipe, feeding into the primary filter, and replaced it with a section of rubber fuel hose (with jubilee clips at each end).

I cut the rubber fuel hose in the middle, and pushed the hose onto the relevant 'in' and 'out' junctions on the pump.

I removed the copper fuel 'in' connection from the primary filter, and clipped the pump's red and black wires directly to +ive and -ive on the engine battery: yes, there's a satisfying clicking sound, and a strong squirt of fuel came out the copper pipe (hopefully, that complied with Paul's advice to purge the line of any copper filings).

I disconnected the +ive lead, and reconnected the pipe to the primary filter, and 'nipped' it up.

Right ..... fingers crossed!

With the electric pump running, I opened the bleed screw on the primary filter, and a good squirt of diesel pulsed about 18 inches across the top of the rocker cover: no noticeable air bubbles, so I retightened that bleed screw.

I cracked open the outlet connection on the (new) mechanical lift pump. Just a small dribble of fuel emerged (presumably the electric pump struggles to push fuel through the static mechanical pump?). With the electric pump still on, and the lever on the mechanical pump also operated by hand, there was then a gush of fuel, so I retightened that connection.

I opened the banjo on the top of the secondary filter. A fair bit of air was soon replaced by a dribble of fuel. When the mechanical pump was also activated, the dribble became more of a gush, so I retightened the banjo.

Onto the injection pump. With the throttle set wide open, I opened both bleed screws. With just the electric pump on, not much action (a dribble of fuel), but with the electric pump on and the mechanical pump's lever actuated, a strong squirt of fuel eventually issued from both points, so I retightened both screws.

Right ....... nearly there ...... I opened two injector unions, about one full turn.

I was alone, so I couldn't watch the action at the injector end, and operate the starter switch, so I ran the starter for about 30 seconds, then rushed aft to retighten the injectors.

Hmmmmm .... fingers deperately, firmly crossed ........ I attempted to start.

Bugger, bugger, bugger ......... still no sign of firing!

I HATE this sort of mechanicking: running is SO much more fun!

......................................

Would you expect the electric pump to push fuel through the static mechanical pump?

Would it be better to bypass the mechanical pump altogether (ie to connect the 'out' side of the primary filter straight to the 'in' side of the secondary filter)? Would that damage the mechanical pump, which would then be running 'dry'?

I'll see if I can persuade Jos to join me today, as chief starter switch operator (so I can watch the injectors).

Phew ...... losing the will to live!

 

[colin.marshall]

Remove the object that has been accidentally sucked into the inlet filter?
Stating the obvious I know but it needs both fuel and air.

I'm lucky that I can do both injector nut and ignition. I can therefore be sure that the nut is tight before stopping cranking. Else I'm guessing you would let air in when you stop cranking.

You could run a jump lead or new cable direct to starter motor, maybe add a switch if you must so that you could do both at same time. Else as you say, get someone. I imagine you are getting fed up making temporary mods and it's always good to get fresh eyes.

As per the stop switch reminders, make sure the throttle lever at engine is moving.

 

[colin.marshall]

And once it's running, everyone over to my engine revving problem as I'm having an equally miserable time but few contributions.....

 

[NealB]

Remove the object that has been accidentally sucked into the inlet filter?
Stating the obvious I know but it needs both fuel and air.

I'm lucky that I can do both injector nut and ignition. I can therefore be sure that the nut is tight before stopping cranking. Else I'm guessing you would let air in when you stop cranking.

You could run a jump lead or new cable direct to starter motor, maybe add a switch if you must so that you could do both at same time. Else as you say, get someone. I imagine you are getting fed up making temporary mods and it's always good to get fresh eyes.

As per the stop switch reminders, make sure the throttle lever at engine is moving.

It's difficult to believe there's anything blocking the air filter, but very quick and easy to check: it's on the list now ...... thank you!

Getting a starter operator shouldn't be too tricky.

The throttle control is definitely moving at the injection pump.

 

[Boater Sam]

There should be very little resistance to flow in the mechanical pump, I would take it off and investigate what is blocking it.

As your problem started with the pump and a new one has not solved it, I would expect the problem to still be the pump, new can be as faulty as old..................

 

[NealB]

There should be very little resistance to flow in the mechanical pump, I would take it off and investigate what is blocking it.

As your problem started with the pump and a new one has not solved it, I would expect the problem to still be the pump, new can be as faulty as old..................

Thank you!

The new pump, to my admittedly very inexpert eyes, seems good. It pumps fuel through the secondary filter, injection pump, and the injectors.

I'm beginning to wonder if the next step is to take off the injection pump and the injectors to be tested.

It's definitely getting beyond my comfort zone (hell, I should either be out motorboating, or working on the sailing boat)!

 

[ghostlymoron]

In my limited experience, injectors and injection pumps don't suddenly fail, it's progressive preceded by lumpy running and blowing out smoke. As your engine was running normally before you fitted the new lift pump, it must be the pump or something you've inadvertently changed when fitting it.
Diesel engines don't need much to get them going - just compression and fuel. Likewise they don't take much to stop them - the usual culprit is air leaking in. The only advice I can offer is to check all the joints for leaks and re make any that are suspect. Good luck

 

[colind3782]

Wrap some blue paper towel around all the joints. That will soon show up a leak.

 

[NealB]

In my limited experience, injectors and injection pumps don't suddenly fail, it's progressive preceded by lumpy running and blowing out smoke. As your engine was running normally before you fitted the new lift pump, it must be the pump or something you've inadvertently changed when fitting it.
Diesel engines don't need much to get them going - just compression and fuel. Likewise they don't take much to stop them - the usual culprit is air leaking in. The only advice I can offer is to check all the joints for leaks and re make any that are suspect. Good luck

Thank you!

Sorry if this seems pedantic, but, as the same misunderstanding has been mentioned before (see #25 and my reply #26), I obviously didn't the explain the situation clearly.

The engine was, indeed, running perfectly with the old lift pump (you've got that bit correct!).

However, it was then switched off, and left absolutely untouched for a couple of days.

Then, still untouched, and still with the old lift pump, it wouldn't start.

I then started checking, and bleeding, and bleeding, and bleeding, with the old lift pump still untouched (other than operating its manual lever).

The non- starting with the old lift pump was the very reason that I got a new lift pump.

So the starting problem has NOT arisen only since the new lift pump was fitted: it pre-dates the new lift pump.

 

[NealB]

Wrap some blue paper towel around all the joints. That will soon show up a leak.

There's no evidence of leaks (though, admittedly, it's got a bit messy in there over the last week and a half).

 

[NealB]

And once it's running, everyone over to my engine revving problem as I'm having an equally miserable time but few contributions.....

Good luck, Colin .... bloody boats!

 

[colin.marshall]

Water in fuel? Makes sure you have fully drained the water separator from bottom.
Sounds like you have the ability now to easily run from a fresh gerry can direct to your pump.
I'm just thinking that if bleeding doesn't work at injector once you are cranking and bleeding at same time, and air filter is fine,
Maybe it's a fuel quality issue. Water or diesel bug?

 

[Bilgediver]

Thanks Paul.

It's silly, I know, but I'm nervous of cutting out a section of copper fuel line, to be replaced with two short sections of rubber hose.

But if it gets it going, it'll feel like I've won euromillions.

Anyway, I'm just off to seek out the nearest Halfords.

I sometimes have this problem after doing work on the fuel system. I don t like the rubber bulb solution so I pressurise the fuel tank using my dinghy foot pump. just very light strokes and soon fuel is issuing from the bleed nipples.

I just hold the hose from the air pump in the fuel filler sealed with a rag. Works every time in seconds.

 

[NealB]

Water in fuel? Makes sure you have fully drained the water separator from bottom.
Sounds like you have the ability now to easily run from a fresh gerry can direct to your pump.
I'm just thinking that if bleeding doesn't work at injector once you are cranking and bleeding at same time, and air filter is fine,
Maybe it's a fuel quality issue. Water or diesel bug?

Thanks Colin.

I changed the primary filter 10 days ago, purely as a precaution. The replaced filter had no signs of water, and no evidence of bug. I sawed the element in half, and, other than smudges of blue paint from the new hacksaw blade, that element was clean as a whistle.

Also, in June 2020, I'd removed the inspection hatches on both fuel tanks, and pumped out all the fuel into plastic cans.

I hand cleaned into the depths of both tanks, and then set up a basic fuel polishing kit (an electric pump and two filters, the second one very fine). I ran the pump for about 5 hours a day for a working week. I also added Marine 16 to each can.

Possibly a bad move, but, as the fuel then looked really clean, I returned it to the tanks.

I have considered rigging up a gravity fed 'tank' of clean fuel, plumbed straight into the injection pump, but that's getting fairly serious for me, so I've not got round to it yet!

I've just had a phone call from a (fairly) local boat engine chap. I'm hopeful he might be able to take a quick look tomorrow.

 

[penberth3]

....I was alone, so I couldn't watch the action at the injector end, and operate the starter switch, so I ran the starter for about 30 seconds, then rushed aft to retighten the injectors.....

It's easy to rig a remote starter switch. A suitable push button switch and a couple of jumper cables to get 12 volts to the starter solenoid.

 

[NealB]

It's easy to rig a remote starter switch. A suitable push button switch and a couple of jumper cables to get 12 volts to the starter solenoid.

I think I remember that my some of my first cars (all mid-sixties 'vintage'), had push and hold buttons on the solenoid.

Presumably not BMCs though.

 

[penberth3]

I think I remember that my some of my first cars (all mid-sixties 'vintage'), had push and hold buttons on the solenoid.

Presumably not BMCs though.

Yes, you're right, but a diesel will have the solenoid on the starter motor with no way of operating it manually. Doing it electrically as I described will work with both types of starter.

 

[Boater Sam]

SIMPLY short the small tag on the starter solenoid to the big one connected to the battery.