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Bleeding the Bleedin’ Perkins

Fuel Flow Diagram

Fuel Flow Diagram

  1. Tools required:
    1. Socket wrench.
    2. 12” socket extension.
    3. 7/16” open ended crescent wrench (to hold the anti-stall adjustment).
    4. 5/16” socket (vent screw on top of governor housing).
    5. 5/16” crescent wrench (side of fuel injection pump body).
    6. 1/2” open ended crescent wrench (fuel injection pump inlet).
    7. 16mm open ended crescent wrench (atomizers).
    8. Extra starter button (or a buddy to help crank the starter).
  2. The Delco-Remy starter has strict starter limitations.
    Delco-Remy Starter w/ external solenoid

    Delco-Remy Starter w/ external solenoid

    1. Never crank more than 15 seconds in a row.
    2. Wait 5 minutes between cranks.
    3. It is tempting to keep cranking, but I have personally burnt out my starter by cranking 15 seconds on, 30 seconds off, 15 on. It will overheat and you’ll need to rebuild the starter’s guts.
  3. Following are the steps described in the manual in outline form. For more detail, read the manual.
    1. Step 1 (Hydraulic head locking screw and air vent screw):
      1. Slacken vent screw on hydraulic head on the side of the fuel injection pump body.

      2. Hydraulic Head Vent Screw

      3. Slacken air vent screw on top of governor housing on fuel injection pump. Ensure anti-stall device is not upset.

      4. Governer Housing Air Vent Screw

      5. Operate priming lever until bubble free fuel issues from each vent. This may take hundreds of pumps if there is a lot of air in the system. To help bleeding, I added a small electric pump inline between the Racor filter and the lift pump. Now I can just turn on the pump for 2 minutes and bleed everything out at ease!)
      6. Tighten the head locking screw.
      7. Tighten the governor vent screw.
    2. Step 2 (Pipe union nut):
      1. Slacken pipe union nut at fuel injection pump inlet.

      2. Pump Inlet

      3. Operate priming lever until bubble free fuel issues from the threads.
      4. Re-tighten.
    3. Step 3 (Unions at atomizer ends):
      1. Slacken the unions at the atomizer ends of the high pressure fuel pipes.
      2. Set the accelerator in the fully open position and ensure that the stop control is in the “run” position.
      3. Turn engine with starter motor until fuel oil, free from air bubbles, issues from all fuel pipes. Some 30 to 60 seconds of rotation may be necessary before this condition is reached (Not all at once! Wait 5 minutes after every 15 seconds of cranking), and the time will be dependent upon speed of rotation and effectiveness of bleeding operation.
        1. Note: Cranking limits for the Delco Remy starter is limited to 15 seconds on 5 minutes off. I needed to refurbish the starter after cranking 30 seconds on, 2 minutes off, 30 seconds on when it started smoking and burnt itself out.
        2. Tighten unions on fuel pipes and engine is ready for starting.
    4. Step 4 (Start the engine and clear all air from injectors)
      1. Reduce the throttle from full open to a high idle before cranking.
      2. Crank the starter.
        1. The cylinders should start to fire. When they do, you will hear the engine try to speed up, hiccup, and almost start. If it doesn’t start after 15 seconds, wait the 5 minutes.
        2. The next cranking session usually causes the engine to start up and run. If it doesn’t, try cracking 2 injectors and crank for 15 seconds, then tighten again. Wait the 5 minutes, then crack the other 2 injectors and crank for 15 seconds. It should at least stumble by this point.
        3. If it’s not firing at all, there may still be air in the injector pump or some other issue. See “Troubleshooting” below.
      3. When the engine starts, adjust the throttle to a high idle if it isn’t already.
        1. The next step involves cracking the injectors, so a high idle is required to keep the engine running.
      4. The engine may be running, but is it running on all cylinders? The next steps will ensure all injectors are air-free.
      5. Crack the first injector.
        1. The engine will stumble but hopefully keep running.
          1. Stumbling is good. It means that injector was running well before you cracked it.
          2. Another good sign is fuel pulsing out in high-pressure squirts.
          3. If no fuel is squirting out, wait until it does.
      6. Tighten the first injector when clean fuel exits the union and the engine should run smoother.
      7. Continue for the rest of the injectors.
        1. If all injectors are bubble-free, each of them will cause the engine to stumble when cracked.
    5. Step 5 (Run engine.)
      1. Turn off the engine and wait a few minutes.
      2. Start the engine again to test for a successful bleeding procedure.

Tools required
Remote start button
Add an electric fuel pump to make life easy!
Connect the start button to the solenoid: Clip one side on the power supply from the battery, the other to the “S” terminal
Lift pump priming lever by the fuel filter
1st vent screw on the hydraulic head locking screw
2nd vent screw on top of the fuel injector pump governor housing
2nd vent screw, closeup
3rd bleed point: Crack the hard line union at the injector pump fuel inlet
Final step: high pressure line unions at the atomizers
  1. Troubleshooting
    1. There are a few possible issues that can prevent the engine from starting.
      1. Air bubbles (most likely).
      2. Fuel restriction (algae, erroneous gaskets, crimped lines).
      3. Air leak.
      4. Bad mechanical lift pump.
      5. Bad injector pump.
      6. Compression? Timing? Valves? Other non-fuel related issues.
    2. Air bubbles
      1. If the engine won’t start, the first step is to completely redo the entire bleed process. Make sure clean fuel with no bubbles comes out at each step. Pump 50 pumps at each step to be 100% sure no bubbles are hiding midway down a line. 50 is more than required to clear the lines.
      2. The engine should start.
    3. Bad mechanical lift pump.
      1. If while bleeding, you don’t feel a strong flow of fuel while pressing the lift pump, maybe it’s not pumping fuel.
      2. It should have smooth resistance as you push down on the lift pump lever.
      3. It then springs back up with zero resistance.
      4. You might also hear the fuel flowing in the system and/or the fuel dropping back into the tank from the engine filter’s fuel return line.
      5. I can pump about twice per second using my thumb.
      6. If you suspect a bad lift pump, try disconnecting the filter fuel return line and see if fuel squirts out when pressing the lift pump lever.
    4. Fuel restriction
      1. Before we get to the horrendous task of tracing an air leak, did you check the filter gaskets? I put the wrong size gasket on the engine filter once where it blocked the holes and the fuel couldn’t flow fast enough to keep the engine running. It sounds hard to do, but the filter came with two sizes of gaskets and I chose the wrong size. Oops.
        1. The symptoms were exactly like an air leak. I was able to bleed the system, filling the injector pump with bubble-free fuel.
        2. I would start the engine and it would run for 15 seconds.
        3. The engine was burning the injector pump fuel but the replacement fuel wouldn’t flow fast enough.
        4. When the engine burnt all the fuel in the injector pump, the engine would die.
        5. What about algae? Maybe it’s blocking a hose. Try disconnecting the hard line at the injector pump inlet. Then pump the lift pump. Solid squirts of fuel should come out of the pipe. If it seems the squirts are slow or there’s a lot of pressure on the lift pump to get the fuel to flow, maybe it’s a restriction somewhere. See the Air Leak section next to trace the fuel restriction.
        6. Check everything with a flashlight and mirror to check for crimped lines.
    5. Air leak
      1. If the engine starts, but only runs for 15 seconds or so before dying, it could be an air leak on the suction side of the system.
      2. A good tool to test for a leak is to replace all the soft fuel lines with clear hose. Then you can see if there are bubbles in the lines while bleeding and while the engine is running.
      3. You can replace the soft lines all the way from the fuel tank to the mechanical lift pump inlet.
      5. If there are no bubbles in any of the clear lines, maybe there’s a leak downstream of your temporary lines. You can’t replace the hard lines with clear hose because of the compression nuts, but you can try forcing fuel out of a crack.
      6. Disconnect the hard line at the fuel injector inlet.
      7. Plug the line with your thumb and pump the lift pump. Pump some pressure up and check for wet spots. Drying everything thoroughly helps spot the leak.
    6. Isolate the problem (Skip components and gravity feed fuel directly to the injector pump)
      1. Get a bucket of clean fuel and set it up on deck.
      2. Run a clear hose from the bucket down to the engine.
      3. Find the hard pipe that runs from the engine fuel filter to the fuel injection pump inlet.
      4. Disconnect the hard pipe from the filter side. (Filter fuel outlet fitting)
      5. With one end of the clear hose in the bucket, let the hose fall into the engine compartment. Then grab the other end and lift it level with the bucket. When siphoning, this will prevent the fuel from getting all over the place, including in your mouth!
      6. Suck on the end until fuel fills the hose, all the way up to a few inches from your mouth and plug it securely with your thumb.
      7. Bring the hose down and quickly fit it onto the hard pipe so there’s a path from the bucket, through the hose, into the hard pipe to the injector pump.
      8. 3 or 4 feet of height is plenty to provide enough pressure to the low-pressure side of the fuel injector pump inlet.
      9. Disconnect the lift pump’s fuel inlet line.
        1. If you forget to disconnect it, the mechanical lift pump will pump fuel out the filter outlet hole while the engine runs.
      10. Bleed the injector pump using the standard method from the manual.
        1. (Head locking screw and governor vent screw)
        2. (Pipe union nut at the injector pump inlet.)
        3. No need to pump the lift pump (it’s disconnected, remember??)
      11. Bleed the atomizers using the standard method from the manual.
        1. (Crack and crank until fuel squirts out.)
      12. Reduce the throttle to high idle.
      13. Crank the engine.
      14. If the engine runs well, the injector pump works.
      15. If not, it’s an injector pump problem.
        1. The injector pump is a very precise piece of machinery and requires a professional to work on it.
        2. It’s also expensive! I paid $585 to have mine refurbished in Hawaii.
        3. The mechanic suspected algae was blocking the fuel flow in the pump and after the refurbishing it worked perfectly using the gravity feed method.
        4. See “Removing the Injector Pump” for more info.
      16. The problem now lies between the lift pump inlet and the injector pump inlet. i.e.:
        1. Lift pump
        2. Engine fuel filter
      17. I’ve never removed my lift pump, but that’s always an option. Check it out.
      18. Triple check the fuel filter.
        1. Are you SURE you used the correct micron number?
        2. Are you sure you fit all the gaskets?
        3. Are you sure the gaskets fit correctly, no weird crimps or twists in it?
        4. Try completely disassembling the filter and reassembling using a new one. It’s a simple part and easy to see a problem once it’s in pieces on a clean rag.
    7. Compression? Timing? Valves? Other?
      1. I have no experience with these issues, but if they ever pop up I’ll be sure to report my findings here.
Dropping the sandwich type filter (See “Replace Fuel Filters” for details)
The top cap should have two gaskets lying flat and smooth, no twists. See the large one in the rim and the small one around the center?
What’s wrong with this picture? The filter in the background has an extra gasket blocking the fuel flow! The bottom cap in the foreground is good.
I found a crack in the return line fitting and had to replace it. I replaced the two copper washers while I was at it.

8 Responses to Bleeding the Bleedin’ Perkins

  1. James Thomson says:
    August 10, 2017 at 8:43 am

    Thanks for the guide!
    I have a Cal 39 Mk II with the 4-108.
    Always been a right pain to bleed.
    The bleed screw on top of the injector pump seems essentila on mine to get it bled.
    I never tried bleeding at the inlet to the IP before. I would have though that would be needed to be done before the bleed points on the IP itself, but seems to work second for you.
    Also, where t bleed at the secondary filter was always a query. Like you I also undid the banjo bolt as that seemed the only way to bleed it.
    I like the idea of using clear tube to check for air leaks.
    Do you leave the clear tube on the whole time?

    One trick that always seems to get me out of trouble after I have bled everything and the engine just won’t quite kick in to action, is to spray some WD40 in the air intake ( as Nigel Calder suggests). Got us out of so many pickles!

    Reply
    • Adam SailorsLifeForMe says:
      August 10, 2017 at 8:50 am

      Thanks for the comment.

      Those clear tubes are just for testing. They are thin walled and I’m not sure how long they would last as a permanent addition. Nobody wants fuel dousing the engine compartment if the hose popped!

      As for bleeding the inlet after the first two bleed points, I was just blindly following the Perkins Manual instructions.

      Good idea with the WD40 or starting ether to give the engine that extra kick. Might save some battery power!

      Reply
    • Al says:
      May 17, 2020 at 3:32 am

      James – how good are you now at bleeding your Perkins? I just can’t seem to nail getting our 4.108 to start :-(

      Reply
  3. Grant Hamilton says:
    October 24, 2021 at 9:03 pm

    How to have a Cal 39 with the Perkins for 108 and yes I to have an engine problem after servicing the filters
    Unfortunately a mechanic opened up the anti-stall device and now I’m just chasing my tail trying to get it to work
    If I open the bleed screw on the top the engine goes to full RPM soon as they tighten it down it’s like there’s a fuel restriction and the engine slows right down
    I can’t get it to go above probably 2000 RPM

    Reply
  4. Nothus says:
    July 31, 2022 at 12:11 am

    Thank you for the helpful videos, which gave me an idea of what I was looking for. We have a 4.107, and though the instructions here are a bit different (start with vent screw on filter, step 2 unnecessary, & only 2 atomizers loosened), your videos helped me figure it all out.

    Reply
  5. Thomas says:
    December 17, 2022 at 2:02 am

    Thanks again for this very useful guide. The videos are absolutely a must watch for supplemental info, like how far to unscrew and what to look for. To add from my own learning experience on my boat, bleed point 1 and 2 can bleed quite a bit of clean fuel before any bubbles show, so definitely don’t just crack and move on. Bleed point 3 didn’t do anything at all until I removed the fitting completely, then it popped and squirted, at which point I could rethread it. Careful not to cross thread here. Each time I turned the fitting, a little bleeding would occur, so I just squiggled it forward and back until it just ran clean fuel by the time I’d tightened it down about 6 full turns. Bleed points 4 though 8 just as the guide says but with the clarification that the injectors and atomizer terminology is interchangeable in this guide. Crack the four, crank intermittently until all wet. Close. Then crank while opening and closing one then the next then the next.

    Reply

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