Engine woes

[pjcomeau]

Over the winter I had my M25XP refurbished (including having the injection pump refurbished) and now after installation we have a couple problem not easily being resolved

1) We keep having to bleed at the first injector. Run engine for a while, then stop let it sit for a while (e.g. overnight), then try again and same problem. bleed at first injector (with it unscrewed, turn engine over a few time, tighten back up and then starts/runs ok). Have done this a few time. Cannot figure out where air coming from. Once running, in neutral, the engine runs smooth, can rev up (kept it under 3200), no smoking, good water flow.

2) After sorting out (temporarily) problem 1, I put into gear and I cannot get above 1700 RPM (may not be exact, but not moving much over 3knots).  Also, there is no smoke.
So I'm assuming fuel problem. From all the threads I've seen here, I know I don't have a screen on the pickup tube, I have the traditional 2 micron twist on Racor filter (replaced during re-installation of engine), the traditional facet lift pump. I could go ahead and replace everything from tank to filter on engine, but with my luck this would not solve my problem and more money spent and still not a properly working engine. Any tips on how to determine problem. I saw that there was a trial by Stu running without lift pump, but with it running (I get slow click when bleeder knob closed and faster clicks when knob open) are there known problems (I will confirm filter inside it, but was not long ago I had it replaced and was clean even when i replace it). As for the Racor filter are there known problems (other then being clogged) that could cause problems. Any tips on determining where restriction may be happening (or even a way to determine if there is a restriction problem in the first place)?

Could the two problems be related.

[KWKloeber]

The experts say that a 2u primary filter is too fine, it will clog too easily.  (I have not had that happen to me (yet!)).

If you suspect a vacuum leak, reverse the process.
Put low air pressure onto the line coming off the secondary filter to the injector pump.
Pinch off, or better plug, the line at the tank fitting.
See if it holds pressure, if not use a spray bottle with dilute detergent or window cleaner to find the bubbling air leak source.

OR

Get a cheap brake line hand vac pump at Horror Fright.  They work very well.  again, pinching or plugging off the hose @ tank, apply a vacuum on the secondary-filter-to-injector-pump hose, and see if your system holds the vacuum.

When you are running, you can crack loosen/tighten the fuel line compression nut on each injector 1-2-3 (use plenty of rags, paper towels, fuel will spray).  If the cyl is firing,  you'll feel an RPM will drop.  If a cyl isn't firing, you won't get the RPM drop.

report back!

-ken

[Ron Hill]

pjco : That sounds exactly like the problem that I had - before I had the injection pump rebuilt!!  Great in neutral and no RPM in gear!!

A thought

[britinusa]

Tough one.

If you disconnected the fuel return hose from the tank and put the end into a fuel jug, then when the pump runs you should have a significant stream of fuel if the bleed valve is partially open.

At least that would confirm that fuel is flowing.

After I repaired a leak in our fuel tank, the fuel did not flow, but the engine ran for more than 5 minutes on just the fuel in the supply hose from the fuel pump. I replaced the fuel pump and primed it (suck on the pump outlet via a transparent hose to avoid sipping any fuel)

Paul

[Robert Mann]

The engine in the Mk 2 will run without the electric fuel pump running.  It basically siphons fuel.  However, the flow while being sufficient to run the engine at idle and at partial load will not sustain normal speeds and loads encountered while motoring.  The electrical connector on mine broke, due to over crimping on assembly and vibration, it took me a while to figure out there was no "clicking" with 12V applied. 

[Craig Illman]

I'd agree with Ron that the injection pump rebuild or reinstallation is suspect. I don't know a good procedure to validate. The "throttle" is actually a governor control, so while it may reach adequate RPM at the dock, under load, it will need more fuel.

Craig

[pjcomeau]

I had the pump rebuilt by a reputable shop that nany others have used (there specialty) As for re-installation  shouldn't  it be noticeable when not in gear too?
Someone mentioned that the  lift  pump may  be  a  problem. I thought I found a replacement locally, but after more research  found that this pump (facet gold-flo) comes in different capacity. The one I  found is 32gph with with max pressure 4 to 5.5 psi. I see on Catalina  direct  site that  it should  be 32gph 6.5 to 8 psi. So I'm assuming the one I found is not adequate ?

[Dave Spencer]

Pierre,
The 4 to 5.5 psi pump will be just fine. No need to fret about 1 or 2 psi for the electric fuel lift pump.

[sailaway]

Did you change the prop if your over pitched it will go slow and smoke. If not its fuel that's all a diesel has. Small micron filters are trouble seen it before. Charlie

[sailr4]

Don't want to dismiss the obvious.  Is your prop clean? It doesn't take much fouling to significantly reduce the rpm's.

[Ken Juul]

You need to start at one end of the fuel system and work your way through it.  You said no screen in the tank, good.  Is the fuel fresh?  Diesel looses it kick after a few months.  Are all the fittings tight and o rings in good shape on the Racor?  Are all the hose clamps tight?  move on to the secondary filter, etc.  My guess is you are sucking air, just need to find where.  Even the best of shops can screw up, if you can't find anything wrong, I'd have the shop double check the injection pump install.

[Ron Hill]

Pierre : I'd definitely have the guys that rebuilt that injection pump recheck it.
Least I remind you that the engine in the C34 will run by gravity feed only - did that for over a year!! 

A thought

[sailaway]

Another place to look the electric fuel pump has a screen in side it. I have seen mine it was terrible. Charlie