Universal diesel surging problem in my sailboat

[acudavid]

Hi Everyone! I am new to the forum. I sail out of Marina Del Rey and have a Capri 25, a Lancer 30 and the boat I am writing about, a 1979 Catalina 30. The Capri is for single-handing and the Catalina is more passenger friendly, so I am planning to sell the Lancer.

The Catalina was repowered by a previous owner and I have little info about the replacement motor. From what I can tell it is a Kubota 750 aka Universal M20 It is a 2 cyl. The serial numbers mean nothing to Westerbeke and Kubota. I have no documentation.

It ran fine when I purchased it, but the next day was hard to start and would surge. Since then we have replaced both injectors, the 12 volt fuel pump, the injector pump, various lines, and the fuel filter. Everything has either been replaced or looks very new. The motor surges at all rpm levels.

I ran an external tank to the hose that connects directly to the fuel injection pump, and it still surges.

I am wondering about a governor? I don't have a manual and am having trouble. Anyone have any experience? I am getting desperate!
Thanks

[Lepke]

Probably the governor unless you have loose linkage or cable.

[Engine man]

The Universal M20 was a Z751 Kubota. TRANSLATION - 2 cylinder diesel, about 0.75 liter displacement = 16 horsepower. Made from 1976 to 1982, about 1000 units were built by Universal. Weight is 365 pounds. I have a parts engine here.

Methinks you have a fuel supply problem. First, charge your start battery. Then Get a CLEAN container of fresh fuel, use clear vinyl hose to connect the container to an electric fuel pump [ can be bought at an auto part store] then to the secondary fuel filter on the engine. Now start the pump, and bleed the system according to the manual. Set the fuel control [in the cockpit] to maximum speed, CLOSE THE INTAKE WATER C-COCK, energize the glow plugs for 30 seconds, shift into neutral, and start the engine. Once it starts, immediately open the c-cock and lower the engine speed to 1500 rpm.

If the engine is hard to start, check the glow plugs for resistance using a VOM. Also check that the wire leading to the plugs is actually energized when you are using the glow plugs.

You should be using Shell Rotella 15W 40 engine oil, or equivalent DIESEL GRADE oil. This will assist in easier engine starting, and a better running, longer lasting engine, as compared to a straight weight oil [ such as 30 weight]

I WOULD NOT mess with the governor unless all other possibilities are eliminated first. Joe

[capt jgw]

Sounds like you covered the usual suspects. Surging is often a clogged filter but apparently not this time. I had a similar problem once and it turned out to be something completely different. The alternator was bad and would cut in and out. Load the engine, unload, load, unload, etc. Sounded just like a clogged filter. I noticed the volt meter was also surging up and down but a little ahead of the engine rpm, the meter would jump up to 14 volts then the engine would slow. Meter dropped to 12 volts, engine would speed up. I disconnected the alt and no more surging. New alternator fixed the problem.

[Bill O]

Originally Posted by acudavid

It ran fine when I purchased it, but the next day was hard to start and would surge. Since then we have replaced both injectors, the 12 volt fuel pump, the injector pump, various lines, and the fuel filter. Everything has either been replaced or looks very new. The motor surges at all rpm levels.

I ran an external tank to the hose that connects directly to the fuel injection pump, and it still surges.

Thanks

Seems like you've hit most of the common issues that would cause a surging problem. To me, it seems like a minor air leak causing the surging. Do like the idea of checking the alternator, since it's very simple to do.

Which fuel filter did you change, external or the one on the motor (secondary filter)? Assumed you bled the fuel system changing the filter on the motor.

Since you have eliminated the tank pick up, would also recheck the primary filter for air leaks and replace all the o-rings. Do you have a vac. gauge on/after your primary? I find these very useful to see some fuel problems at a glance.

If all else fails, call Kubota or even Beta Marine to see if their tech people have any other things to check.

[c.K.]

Originally Posted by acudavid

Hi Everyone! I am new to the forum. I sail out of Marina Del Rey and have a Capri 25, a Lancer 30 and the boat I am writing about, a 1979 Catalina 30. The Capri is for single-handing and the Catalina is more passenger friendly, so I am planning to sell the Lancer.

The Catalina was repowered by a previous owner and I have little info about the replacement motor. From what I can tell it is a Kubota 750 aka Universal M20 It is a 2 cyl. The serial numbers mean nothing to Westerbeke and Kubota. I have no documentation.

It ran fine when I purchased it, but the next day was hard to start and would surge. Since then we have replaced both injectors, the 12 volt fuel pump, the injector pump, various lines, and the fuel filter. Everything has either been replaced or looks very new. The motor surges at all rpm levels.

I ran an external tank to the hose that connects directly to the fuel injection pump, and it still surges.

I am wondering about a governor? I don't have a manual and am having trouble. Anyone have any experience? I am getting desperate!
Thanks

An unlikely suspect, tank pickup usually a flaired compression fitting it is not good enough to check how tight the nut is but the flaired nipple see if you can hand spin it . if so grind down the nut a bit and try again ( i had this issue as well )

[sinnerman]

Info(PDF) in the Universal engines (which are made from Kubota tractor engines as you stated:


Parts breakdowns for the universal engines:


https://shop.toadmarinesupply.com/ma...tname=catalogs

[sinnerman]

When you set the throttle on the diesel engine, you are actually setting an engine "Speed" for the motor to regulate at.

If the speed drops below the set speed, the governor system , through springs directs the injector pump to send more fuel to the injectors to increase engine speed.

If the engine goes above the set speed, the fuel quantity to the injectors is reduced. The governor and injector pup are continuously regulating to adjust for changes in engine load to keep the speed constant.

That being said, the rack in the injector pump could be sticking.

Another item could be the springs:
On the Kubota 3 cylinder I have , there are TWO springs (that sit one inside the other) which transfer the governor feedback to the fuel injector rack. If one of the springs is missing, stretched or disconnected, it may over-correct and cause the engine to "hunt" .

Hooking the fuel hose directly to the injector pump is probably not a good way to troubleshoot as I believe the pump requires the fuel PUMP's pressure to properly push fuel through the system . Gravity alone will not do it.

Make sure you do not have a problem as well with a clogged air filter or exhaust.

My two cents.

cheers

[Stu Jackson]

Also this:


Fuel Starvation and The Obscure Check Ball Valve
https://c34.org/bbs/index.php/topic,10681.0.html
and
https://forums.sailboatowners.com/th...l%20Starvation

[sinnerman]

Stu (above) is the go-to guy for these diesels..

[sinnerman]

more info

[Apollo366]

When I had this problem it turned out to be the exhaust elbow.

Ask a mech to check is all I can think of.

[Dave_S]

Do these engines have an EGR valve. I had issues with my truck and I was convinced it was fuel related but it turned out to be the valve.

[Sailmonkey]

Originally Posted by Dave_S

Do these engines have an EGR valve. I had issues with my truck and I was convinced it was fuel related but it turned out to be the valve.

Nope, no egr