Lehman SP135 Wont Start

[TassieBloke]

Dear All,

I have got to a point where I need input from those who know ;-)

A week ago or so, I did my start up to keep things in order, and things were normal as usual. Cranked over, started normally etc. Anyway after about 5 mins, my Lehman just simply stopped. No spluttering, no catching on then dying etc, just stopped like I pressed the stop button. I checked the filters, fuel supply etc. I thought I may copped some water in the fuel, so flushed the filters with fresh diesel, re-primed everything, and tried to start. No go. It simply will not start. I will list what I have tried to get it going (not in order).

Flushed the engine mounted filters - no signs of water.
Flushed the pre-engine filters - no water in the bowls.
Rigged temporary fuel supply from jerry can with new diesel.
Primed with separate electric lift pump to prime all filters and injection pump - fuel flowing freely.
Cracked front injector pipe to expel air - also while starting
Cracked nut on injection pump housing to expel air.
Used separate lift pump to pressurize fuel system when trying to start.
Checked stop lever is back in normal position for starting.
Check fuel stop solenoid (from hi temp sensor on header tank) for normal operation.

With all of the above, there is no fuel coming out from the pump to the injector lines. Normally when I crack the first injector line nut, it will start fine, and then when I close the nut it settles down to nice idle.

I know that you shouldn't have to crack that nut to start. It is an old pump, and obviously the fuel flows back over time so it needs re-priming, but this is not in the space of hours, more like a week or so. But once primed, it has always started without fault.

What am I missing? There is obviously something stopping the fuel exiting the pump, or getting to the plungers in the pump. I want to exhaust all possibilities before removing the pump to be checked. Btw, it is a Minimec pump.

Any ideas?

Thanks

[Lepke]

I don't know your engine well, but it sounds like the stop solenoid. Usually they are powered when the key is on. It moves a valve in the injector pump that opens when powered. Failure usually shows no fuel coming from the injector lines. The problem could be a bad solenoid or the solenoid not getting power.

You need to find where the stop solenoid is and see if you have power to it. If you have power, then it probably means a failed solenoid. Every time I've seen that problem, the engine just shuts off like turning off the key. The engine won't start, not even try. The stop solenoid doesn't need to come from a marine engine dealer. I usually buy them on eBay for about 1/4 the price.

[TassieBloke]

Hi Lepke,

I have already checked the stop solenoid, and it has normal range of movement. This is an old engine where the stop lever in the rest position is open to start. The stop solenoid is activated by a separate button to stop, which when pressed kills the fuel flow.

Thanks anyway fro your input

[dickhein]

It sounds to me like a bad lift pump. They are mechanical, no electric connections. Ez to replace. Call Brian at American Diesel. They are not expensive. Brian will freely give excellent advice.

[Uncle Bob]

Originally Posted by dickhein

It sounds to me like a bad lift pump. They are mechanical, no electric connections. Ez to replace. Call Brian at American Diesel. They are not expensive. Brian will freely give excellent advice.

Perhaps you didn't notice but the OP is in Melbourne, AUSTRALIA.

[TassieBloke]

Originally Posted by dickhein

It sounds to me like a bad lift pump. They are mechanical, no electric connections. Ez to replace. Call Brian at American Diesel. They are not expensive. Brian will freely give excellent advice.

Thanks for the tip.

I bypassed the mechanical lift pump by directly feeding the fuel filters with an electric Facet fuel pump from a clean fuel source. Made no difference.

[skipperpete]

Are you getting any fuel at all from the injector pipe unions when you loosen them at the pump? If no fuel at all while operating the starter then you might like to do the "last resort" diagnostic. Remove the rectangular cover on the side of the injector pump and put it in a clean tray. Inside the exposed area you will see a horizontal bar that rotates the pump elements/plungers called the fuel rack. With a clean or gloved finger try to move the rack longitudinally. It should move easily and it it should move when the stop lever is operated. If it's hard to move the rack or if the stop control has no effect or the rack is stuck tight then one of the elements has seized in the pump. If this is the case , make no attempt to start the engine because it may have an ungoverned overspeed.
Only do this diagnostic if it is absolutely certain that the fuel supply is perfectly adequate and air bubble free and has been eliminated as the cause of the problem.
If the rack is stuck, the pump has to be taken to a pump technician for repair..... easy to remove it though.

[TassieBloke]

Hi Skipperpete,

This is exactly the info I was hoping for [emoji106][emoji106]

I will again carefully check the fuel flow again using the electric fuel pump. Then will give removing the side cover a whirl in the next few days.

Thanks [emoji846]

[wrwakefield]

On my Lehman SP90 [4 cyl 90hp] I once had the opposite experience: The stop button wouldn't kill the engine.

I confirmed the solenoid was activated by the button, and the stop lever moved what appeared to be the requisite distance.

After scrutinizing everything I discovered [and it wasn't obvious at a glance...] the linkage between the solenoid and stop arm had self-adjusted [longer] because a lock nut had vibrated loose.

Readjusting the linkage length and locking the nut took care of it [for 4 years and counting...]

I know you already examining the stop solenoid, but mention this in case it applies in reverse for your issue. [i.e., the linkage tightened itself and is engaging the stop lever without soleniod activation...]

Best wishes sorting it out.

Cheers! Bill

[moseriw]

I did not find an information if you bleeded the fuel system or not. The diesel injector pump has 2 screws. RTFM and find them. Then open them. Let someone els start the engine. Wait until enough fuel comes out of the bleeding screws. Then close them.

Maybe your engine have not got enough fuel at the first attempt and you have air in the pump.

[TassieBloke]

Well, I have removed to side cover and did as Skipperpete suggested. The rack moves freely back and forward.

Rechecked also the suggestion of the stop lever and its movement. It continues to move a few degrees after the rack has returned to its apparent rest position, so no obvious restriction of fuel flow there.

What to do? My immediate thoughts are to now bypass the whole fuel filter set up (both pre-engine and engine mounted), and then use my external electric lift pump to presurrise the injection pump, and bleed it as I have before. While still pressurised (electric fuel pump running), try to start with first injection line nut cracked and see how that goes.

Comments?

[TassieBloke]

Originally Posted by moseriw

I did not find an information if you bleeded the fuel system or not. The diesel injector pump has 2 screws. RTFM and find them. Then open them. Let someone els start the engine. Wait until enough fuel comes out of the bleeding screws. Then close them.

Maybe your engine have not got enough fuel at the first attempt and you have air in the pump.

I am not sure how I should respond to this, but thanks for the comments [emoji846]

Btw, the FM did not come with the 40yr old boat. Internet searches have revealed a shedload of different nuances to the CAV pump that is mounted on this particular engine.

[Wotname]

Originally Posted by TassieBloke

Dear All,

I have got to a point where I need input from those who know ;-)

A week ago or so, I did my start up to keep things in order, and things were normal as usual. Cranked over, started normally etc. Anyway after about 5 mins, my Lehman just simply stopped. No spluttering, no catching on then dying etc, just stopped like I pressed the stop button. ..............

What am I missing? ..........

Any ideas?

Thanks

Disclaimer - I don't know much about this engine

But I know a little bit about older diesels in general so I offer the following comments on a FWIW basis.

Given the sudden unexpected stop, it does sound like the stop function has activated but you apparently have proved that to be OK so....

Presumably the injection pump is cam driven but by what shaft (camshaft or lay shaft or something else)?

Is it possible the shaft that operates the injection pump has stopped turning?

[moseriw]

OK: here is your original manual

Lehman-SP135-owners.pdf


For my Lehman 2712E it look like this:

[skipperpete]

Originally Posted by TassieBloke

Well, I have removed to side cover and did as Skipperpete suggested. The rack moves freely back and forward.

Rechecked also the suggestion of the stop lever and its movement. It continues to move a few degrees after the rack has returned to its apparent rest position, so no obvious restriction of fuel flow there.

What to do? My immediate thoughts are to now bypass the whole fuel filter set up (both pre-engine and engine mounted), and then use my external electric lift pump to presurrise the injection pump, and bleed it as I have before. While still pressurised (electric fuel pump running), try to start with first injection line nut cracked and see how that goes.

Comments?Attachment 200883

It looks fairly clear in the pump pics that you have been bleeding the pump case vent screw and if you get a good fuel flow out of that bleed point there is no logical reason why this engine won't fire up, especially knowing that the rack moves freely. At this point a diesel mechanic would open all the injection line nuts and get an offsider to crank the engine ..... with the seacock closed.... and operate the rack directly by hand until fuel starts to appear at the unions, then lock up the nuts and try a start. Watch the pump elements and springs in the window for the normal movement up and down as the engine rotates. There is an outside chance that the injector pump drive gear retaining nut has come loose and the key has sheared , either changing the timing or completely disengaging from the pump. This could explain the sudden stop.
It's also possible to observe the pump gear rotation through the little timing window by removing the hex plug on the pump mounting flange and rotating the engine manually with a socket and bar.
I'm really baffled why she won't fire up , these Fords start quickly even after long periods of layup (10 years and more) wit the barest amount of priming. 🤢[emoji848]