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Discussion Starter · #1 · (Edited)
Hi All, sorry for the repeat post, but don't think the "diesel" thread gets as much traffic. This is about my Universal 5424 diesel.

Story: Firday I changed the Racor fuel/water separator and the engine fuel filter along with 3-4 feet of fuel line. I filled up the filters with fuel before screwing them in, and bled the system at the injection pump using the electric pump and it started right up and ran OK dockside. Next day, took her out and we died (ran out of fuel) three times. Found out I didn't bleed at the engine fuel filter. :mad: So today I bled the fuel filter, then the injection pump and purred like a kitten, never stalled, just like new until we tried to get max power. It would only get to about 2400 RPM (max is 2800). Before I did the fuel filters, 2800 RPM was available on demand. We went out and motored for a good hour and could never get above 2400. I am really perplexed. Anyone had this happen to them?

Dave
 

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The only thing I can think of is gunk in the jets, in the injectors.


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My first thought would be the state of the bottom and the prop; are they clean?
I have had a Racor filter plug up before the cartridge, in the intake tube, but that is extremely rare.
Are the engine rpms constant at idle? If not, this is a sign of air entering the system. I would make sure you have not rolled or crimped a gasket (did you lube the gaskets with oil before reassembling the filters?) and that everything is air tight. Also check that the throttle cable set screw on the engine hasn't slipped or on the throttle handle.
Your injector tips shouldn't just foul without very dirty fuel bypassing the filters, so that should be a last resort.
 

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Senior Smart Aleck
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Hi All, sorry for the repeat post, but don't think the "diesel" thread gets as much traffic. This is about my Universal 1524 diesel... I am really perplexed. Anyone had this happen to them?

Dave
There is a knob on the top of my Racor filter housing for a valve that is used to shut off the fuel supply when changing the filter. You tighten it and loosen it in exactly the opposite the normal expected direction. The valve allows one to change the filter and/or drain the bowl of sediment without the bowl refilling during the process.

Did you re-open that valve completely at the top of the Racor filter housing after changing the primary fuel filter?
 

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You changed the filters, now you have lower than normal rpm ....

Now go back and recheck your filter installation and carefully scrutinize if or not you 'pinched' a filter gasket or a filter sump O-ring, overtightened and cracked a tubing connection, etc. What you describe is quite similar to a 'small' air leak in the fuel system ... the small amount of air is drawn into the delivery system and the small bubbles of air that are 'entrained' dilute the 'total heat value' of the fuel .... not enough air leak to stall the engine but just enough to degrade engine performance. Such gaskets and 0-rings should not be installed dry; but, 'lubricated' by wetting them with diesel oil during the installation - lubricating them will allow closure without 'distortion' of the seal. Straight 30 weight oil is a better 'lube' for these 'gaskets'.

If you 'opened' any 'compression fittings' (not flare fittings) in the system, carefully open them and also recheck (w/ magnifying glass or pocket microscope for cracks on the 'nut') to see if the small brass 'ferrule' thats inside the fitting still fits 'tight' onto the copper tube. If not, then cut back the copper tube and reinstall the ferrule onto 'undeformed' copper. Compression fittings are notorious 'leakers' -- should only be loosened/tightened 'once' ... REPLACE with a proper flare fitting or 'ring-seal' fitting.
 

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x2 on lubing seals, o rings gaskets, etc...I always use oil when new...in fuel related scnearios...after that they get their shape and its a matter of not messing with that shape to get it back on...
 

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additionally .... the modern 'blends' of diesel fuel can cause the old standby rubber compounds Buna and Neoprene to 'swell' and soften, especially so when there is any trace of 'bio-fuels' (reclaimed cooking oil, etc.) added to the blend. Always use NEW o-rings and gaskets when changing fuel filters.
 

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Discussion Starter · #8 ·
Thanks Guys!

All good thougths. I'm going to the boat tomorrow and I'll go back through the "basics". I will report back what I find and what the results are.

Dave
 

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If you have an electric fuel pump, it probably has a filter that is clogged too. Also, some boats have fuel pickup hoses in the tanks that are "protected" by a mesh screen which clogs up.
Might just be coincidence that it happened when you changed the other filters.
 

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Discussion Starter · #10 ·
If you have an electric fuel pump, it probably has a filter that is clogged too. Also, some boats have fuel pickup hoses in the tanks that are "protected" by a mesh screen which clogs up.
Might just be coincidence that it happened when you changed the other filters.
Maybe... I learned a long time ago in mechanics... "if it worked fine before you messed with it... you did something to it to make it not work". Now that being said... your correct - there's always that possibility of coincidence. The electric pump screen is easy enough to have a look at. Thanks.
 

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Discussion Starter · #11 · (Edited)
Follow up report. I removed both the Racor and the engine fuel filters, checked, cleaned and lubed all seals and O ring, replaced the engine filter and bled per the manual (key on - electric pump on, open the the engine filter bleed, got flow, then open the fuel control bleed, get flow). Went out last night and it went to 2600, pulled it back, then up again - hit 2800 RPM (max rated) and stayed there. Runs great throughout the RPM range just like it did before I touched it.

FOLLOW THE OWNERS MANUAL BLEEDING PROCEDURES regardless of how much you think you think you know how to do it.
 

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Have a look at the Racor filter insert. They do them in several grades, from 4 micron to 20 I think and some engines don't like the fine 4 micron one as it is a bit tougher to pull the fuel through it. Yanmar state in their manual not to use the 4 micron filter because of that. I use it in my Lombardini and that way I don't have to change the filter on the engine. Its worth having a look at.


ATB

Michaell
 
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