Perkins Bleeds, Starts, then Quits.

[beebopbogo]

I just replaced my engine fuel filter on the ol' Perkins 4-108 and she'll only run for 15 seconds after bleeding! Air in the system?

So I bled it again, full meal deal from lower and upper bleed screw on the injector pump, to the injector inlet pipe and finally the 4 injector pipes. After running the starter and cracking injectors from 1 to 4 she'll start right up before reaching the 4th injector. I set a high idle and cracked the 4th injector for a couple seconds but it already had string squirts of fuel coming out and closed her back up.

She ran for a total of 15 seconds before just shutting down. No slowing it stumbling first, just done! As if I had hit the stop switch.

Replaced all the copper washers (some were quite ratty), checked the quality of the pipe connections (all good), soft hoses all look nice and tight.

Any suggestions or tricks on how to find the leak (if indeed that's what it is?) I'm out of ideas!

[S/V Antares]

Sounds like the issue is before the on engine filter or fuel pump

1. Did it run OK before you changed the filter?

2. Do you have the CAV "on engine" filter? The o rings can be a P I T A

3. Do you have an "Off engine" filter and did you change it? Fill it before starting?

The CAV Injection pump is lubed by the fuel oil itself (no sump) a 4-108 will run about 15 seconds on the fuel in the pump if it is not getting any from down stream (Filter ,tank etc) Sounds like you are sucking air in somewhere.

I put an outboard fuel bulb between the tank and engine and bleed it. Then squeeze it while the engine is running. If it runs but stops when you stop squeezing look for the leak Good luck With a little logic and patience you will get it.

[beebopbogo]

1. Yes. Ran great for 8 months, then changed the Racor filter, motored four more times sailing that week, the suction gauge on the Racor was still in the red so I changed the secondary filter on the engine.

2. Over the course of 2 weeks now, I've reset the filter twice double and triple checking the o-rings and seating of the filter, once myself, the second time by a Perkins mechanic. I feel like I've checked every source for leaks.

What are the symptoms of a failed lift pump? The Perkins lift pump is mechanical just prior to the engine fuel filter. However,
I have one of those cylindrical $150 Napa electric fuel pumps running the entire time providing continuous fuel from the tank to the Racor filter. Would that provide enough pressure if the lift pump failed? Hmmm... Maybe I could bypass the lift pump.

One more note: it seems to bleed fine, filling the injector pump with pure fuel, no bubbles. But once running the engine, air is introduced. Why would that be?

Sent from my XT1030 using Cruisers Sailing Forum mobile app

[LeaseOnLife]

Originally Posted by beebopbogo

1. Yes. Ran great for 8 months, then changed the Racor filter, motored four more times sailing that week, the suction gauge on the Racor was still in the red so I changed the secondary filter on the engine.

The Racor suction gauge being in the red would indicate a blockage at or before the Racor filter (between tank and RACOR filter).

That blockage could cause air being sucked in between RACOR and engine.

[SkiprJohn]

It really sounds like you have an air leak in the system and need to start at the fuel inlet pipe in the tank and trace from that to the injectors. Since the last thing you did before it started failing was change the filters then that's probably where you'll find the air leak but starting from the beginning is the best way to sort all leaks out.

If you can bypass your filters with a fuel can that uses gravity feed by tapping in after your filters and see if it runs good from there. You can eliminate each spot by tapping in at different places with your fuel can.

You can clean and dry every pipe and hose very well and use your electric fuel pump to see if you can find a wet spot anywhere along those areas. If fuel will leak out then air can leak in. Check the bottom of each filter housing to make certain no air can get in there. Any bleed or drain screws can allow air in.

Make certain that filters aren't installed upside down or gaskets are not installed the wrong way.

I wish you the best of luck. These things are really hard to sort out.

[Wolfy]

If you have a "on Engine" screw on type Fuel Filter (Secondary) check that the old Square type "O" ring from the old fuel filter is not still stuck up against the upper housing....if the fuel filters haven't been changed for a while this can happen....so, if the old square type "O" Ring is still there and you screw on the new fuel filter...all you get is air being introduced into the system due to having two "O" Rings.
With the Racors....did you remember the really small "O" ring at the top of the filter housing....where the securing "T" screw is located??
Worth a look.....
Your sucking air in from somewhere.....must be something really silly....

[steamgoat]

Maybe you have a strainer on the fuel pick up in the tank,that being pluged would cause the racor vac gauge to be in the red.Blow through the line back into the tank to see if it clears.

[lancelot9898]

The O rings on the filters are always suspect and not getting them seated properly or lubricated could be the problem. As an aside, I've always followed the instructions in the Perkins 4-108 workshop manual when bleeding the fuel line. Some steps I might skip and still be able to start the engine, but bleeding the air out of the lines was always a pain. Last week I replaced the fuel filter and had to bleed the lines. However this time I discovered for the first time that I could do it entirely just cracking two unions around the fuel filter itself. The first union is the return line from the filter to the tanks and the second union is the line from the filter to the injection pump. (My filter does not have a vent valve.) I opened and closed those points in sequence while pumping the lift pump until solid fuel came forth. Started right up and ran without having to mess with the high pressure side of the fuel line including the injector unions.

[gordwedman]

I recently installed a pair of Racor 500fg filters in series and I could not get the first filter to completely fill when using my electric bleed pump. Figured it was somehow defective so I removed it. That is when I discovered a hairline crack in the inlet hose where it was clamped to the hose barb. It seems that being on the suction side it never had enough pressure to leak fuel but would admit some air when I ran the bleed pump.

[Lancerbye]

The problem you are having sounds like the same one that happened to a fellow in the marina here. He had changed the secondary engine filter, the primary filter etc. The engine would start run 10 to 15 seconds and stop. He did all kinds of things trying to solve his problem. His was a perkins 4.154. Since he knew I had Perkins he asked for my help. So I helped him chase this for awhile and examined the secondary filter for the second time. Turns out that the cross reference for the original filter is wrong. The so called replacement has no holes in the top of the filter. I had some Fram originals for my Perkins 4.236. Gave him one and the engine started right up. After that experience I have little faith in the jobber cross references. Examine the top of the secondary filter and compare it with the original that you took out.

[KDH]

Do you still have the original t handle for your primary racor filter? I bought a vacuum gauge but have been unable to get it to work as it leaks air even when installed properly! This once resulted in an hours long delay in bleeding the engine. Also, you have to bleed the secondary filter.

[S/V Antares]

It would appear to be a restriction before the Racor. Open the Racor and check the level If it is an inch or two below the top it is pulling air in the filter or before it.

I agree it may be the pickup tube. Run it on a 5 gallon jug to the electric pump >. Don't worry about the return flow.

Another great tool is a simple short piece of clear vinyl hose. Place it in line beginning at the tank connection and look for bubbles. Move it to the next connection up stream if no bubbles show up.

[S/V Antares]

One other quick item..... the Fuel pump (Cylindrical type ) has a filter in the bottom if it is the one I think it is.

[beebopbogo]

Update to my bleeding problem: ("Bleeding" is an expletive at this point, btw.)

I replaced all the rubber fuel hoses with clear hose temporarily for this troubleshooting exercise. I also removed the electric fuel pump to return the Perkins setup to its original state.

1) Opened the fuel tank access port, dropped an end of the clear hose in 6 inches and secured it.
2) Plugged the other end into the Racor.
3) With a second length of clear hose, I connected the Racor's "out" to the mechanical lift pump's "in." So clear hose from Tank --> Racor --> Lift Pump. Then hard lines connect Lift Pump --> Engine Filter --> Injector Pump --> 4 Injectors.

I bled all the air out of the lines, then blocked the tank hose so I could fill the Racor without it draining back to the tank. Then pumped some more until the fuel was pure, not even a speck of bubble. So no air is getting in, right?

I completed the bleed process at the bleed ports and injector pipes and started the engine. 20 seconds of no bubbles visible and smooth running. Then it slowed for 5 second before dying. But get this. No bubbles in the clear house until AFTER it started slowing! I'm guessing these bubbles are somehow back flowing from an air source AHEAD of the clear hose. Lift pump? Filter? Injector pump?

I think prior to the lift pump can be said to be in good shape.

I was thinking how to supply clean Jerry can fuel directly to the injector pump using gravity to supply the pressure. But how do I get a tight fit to the pump inlet? I may have to engineer something using a fuel pipe from Napa... Unless there's an easier way to troubleshoot the question: bad lift pump, filter, or injector pump?

For those of who who will immediately say "gotta be the filter," I already disassembled it, replaced all (yes, all 3) gaskets, used the exact duplicate filter as the one that's worked for the past 8 months (Wix 33166), replaced the copper washers with new ones and snugged tight, and checked the quality of the fuel pipe bulbs and threads. All looking awesome.

Sent from my XT1030 using Cruisers Sailing Forum mobile app

[DeepFrz]

When you replaced the fuel line did the vacuum gauge reading drop to near zero? If so them maybe you have two problems.

There should be a one way valve in the Racor to stop fuel from flowing back so you shouldn't have had to block the fuel line. Are you sure you have the fuel lines in the correct in/out locations?

You talk about plugging the hose into the Racor. Did you use a proper fitting or just jam the hose in?

I agree that running CLEAN fuel from a can or bottle into the fuel system upstream of the lift pump to be the next step. At least that would be my next step. Edit: it doesn't need to be as large as a Jerry can.