12-71 fuel pump

[MVCaprice]

I have been observing low fuel pressure on our stbd side engine at the engine filter and mildly hard starts as well as some idle surging. I am suspecting the fuel pump. Has anyone experinced similar symptoms? Also is the stbd a right hand or left hand rotation pump?

 

[Avenger]

Any number of fuel system problems can cause the symptoms you are referring to. Don't condemn the pump without checking for restrictions, air leaks or other fuel quality issues. Fuel pump rotation is marked on the pump itself.

 

[dottieshusband]

I have been observing low fuel pressure on our stbd side engine at the engine filter and mildly hard starts as well as some idle surging. I am suspecting the fuel pump. Has anyone experinced similar symptoms? Also is the stbd a right hand or left hand rotation pump?

I don't know your boat, but my 1987, 63MY is CW on the Starbord, CCW on port. The fuel pump is difficult to see. An easier way might be to look at your starter motor on that side. The CCW side will say something like Delco 50TCCW.

 

[MVCaprice]

Any number of fuel system problems can cause the symptoms you are referring to. Don't condemn the pump without checking for restrictions, air leaks or other fuel quality issues. Fuel pump rotation is marked on the pump itself.

This is good advise. So far I have replaced the racor filter, engine fuel filter and also replaced a leaking reference line that was connected to the mechanical fuel pressure guage which was also bad. I have also tried altering the feed and return lines to the other tank. All signs point to the pump. Any other suggestions?

 

[Avenger]

Thanks. I always try to give goo advice.

If you really want to dig the only other things I can think of are installing a section of clear hose near the secondary filter to make sure there's no air. Also isn't there is a pressure regulator on the return from the heads that maintains rail pressure? You may want throw an eyeball on that. OTOH, we may be overthinking it and at this point it probably is the fuel pump.

 

[MVCaprice]

Thanks. I always try to give goo advice.

If you really want to dig the only other things I can think of are installing a section of clear hose near the secondary filter to make sure there's no air. Also isn't there is a pressure regulator on the return from the heads that maintains rail pressure? You may want throw an eyeball on that. OTOH, we may be overthinking it and at this point it probably is the fuel pump.

I don't think there is a pressure regulator, only a pressure release at the pump. The other possibility is a bad injector, but I am not seeing a great deal of smoke or any other bad injector symptoms.

 

[Glory]

Put a gauge on it!

 

[MVCaprice]

Put a gauge on it!

I have a guage on the pressure side of the pump at the filter housing which is how I know there is a problem.

Stbd engine has less than 5psi at idle, 40pi at Cruise. Port has 15-20psi at idle and 60psi at cruise.

 

[Boatsb]

Change the $125 pump and see if it's the problem.

It's taken more time than worth.

 

[racclarkson@gmail.com]

For what's its worth...both my 1271's idle at 4-5 psi and run in the 40-45 range at 1750 rpm cruise. I have no issues as you describe. In fact, I posted last month about running a tank dry and using my cross connect system to run both engines at cruise off of one pump for two days. My filters are clean; i.e., no known restrictions.

There is a idle screw governor adjustment for rolling rpm, but if it clears up on its own after warming up for a few minutes...

 

[MVCaprice]

Small update: I went through and cleaned up the bowls in the racors and changed the filters and noticed a slight increase in pressure in the neighborhood of 5psi at idle and at cruise. I still haven't changed the pump but I sourced a new pump to throw in when I get a chance. I'll report back with additional findings.

 

[SEVEN]

One more idea. While the motor is running look at the racor bowl with a flash light. See if there are bubbles coming from the valve at the bottom. They maybe small but if you see them replace the bowl and gasket. This could surely help solve your issue. It worked for me.

 

[MVCaprice]

One more idea. While the motor is running look at the racor bowl with a flash light. See if there are bubbles coming from the valve at the bottom. They maybe small but if you see them replace the bowl and gasket. This could surely help solve your issue. It worked for me.

It's funny you mention this. One of the bowls has a valve that I think is in rough shape. I have replacement drain valve for it that I haven' installed yet. I'll give that a shot sooner rater than later.

 

[mykim]

I'm reading this pretty late and you likely have it fixed already. Stbd 12v71 is a left hand motor. A new pump from Diesel pro is around $200. They also sell rebuilds.

I did all my own and it was very time consuming. A pro can do it in an hour or so. Also, what you are describing is classic pump failure. They seldom just quit. More likely to die a slow death.

Good luck.