Perkins 6.354: Starts, surges, then dies

And lube the new o rings/seals with either diesel or Vaseline so they seal well.

sunchaser said:

Brian

Two questions

1. What is the level of the fuel in the tank in relation to the Racor?
2. Are both engines drawing from the same or different tanks?

The fuel lift pump change out will certainly fill in a few blanks.

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If the tank were completely full, the level would be to an inch or two below the tops of the Racors. But the fuel level now is considerably lower, maybe even below the bottom of the Racors.

The boat has only one fuel tank. Each engine has a separate "tap" into the top of the tank, with its own tube, shut-off valve, line to the Racor, etc. IOW, completely separate fuel systems, drawing from a common tank.

jleonard said:

And lube the new o rings/seals with either diesel or Vaseline so they seal well.

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Yep, learned that from my dad, the first time we changed the oil in my car when I was 16. Never install a dry gasket or o-ring.

Shoalwaters said:

Ah Ha! So problem appears after filter change eh?

There is an O-ring seal around the shaft of the T-handle. Did you change that too?

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Yep. And today, I'm going to swap the lids between the two Racors as a test of something in the lid leaking. But it's such a simple thing (the lid, gasket and o-ring), and everything looks clean and in great shape, I doubt that's it. Thanks, though.

RT Firefly said:

Greetings,
Mr. BS. Aha! It has to be....EXACTLY the same scenario as I conveyed in post #19. Engine stalls, Racor low on fuel. Replace that 4' of heavy gauge flexible fuel line.

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Alright, RTF - that makes the most sense, so that'll be today's Job One.

Greetings,
Mr. BS. Well, sir, if it ISN'T the problem I give you permission to be the first this week to call me a craven, flap mouthed wagtail.

Do you have a vacuum gauge on top of your Racor? IF so is it rising at all or staying on 0? These are a great tools for trouble shooting issues like you are having.

On many vessels the Racor is well below the fuel level providing the desired flooded suction at that point. With your Racor bowl partially emptying it indicates either fuel is draining back to the tank due to a air leak at the Racor or line up to injection pump. Or as RT suggests a Racor feed line issue.

Keep at it Brian you will get there

RT, as it's Saturday, and my local hydraulic supply shop is closed, this will have to wait until... well, after Thanksgiving at this point. (Heading out of town Monday morning for a week.)

Sunchaser, there is a vacuum gauge on top of the Racor, and it's inconsistent. During this ordeal, I've seen it go up to as much as about 3 inches while the engine is running, but yesterday while it was running, it was resting on 0. If all is working as it should, there should be a small amount of vacuum, right? Too much is bad (dirty filter, probably), but too little is bad, too? (Air is pulling on the base of the gauge, rather than liquid?)

New lift pump and Racor rebuild kit both ordered. Soon, I will have replaced or rebuilt the entire system from the top of the fuel tank to the lift pump. After that, it's a solid metal pipe to the on-engine filter, and only solid metal pips from that point on.

BTW, today when taking pix of the lift pump to make sure I buy the right one, I noticed the one on the trouble engine is pretty old, while the one on the other engine looks to have been replaced quite recently. Doesn't prove anything, I know, but does seem to add a little suspicion to the lift pump.

Glad I've got some time before the next planned voyage. Thanks, all, for the input!

Gabe n Em said:

quick cheater for the lift pump instead of laying on the engine (god forbid it's hot):

1. drill a small hole near the end of that lever.
2. run a string/wire/whatever through it
3. attach it to the ceiling(bulkhead?) above the engine so you can just reach across and pull the string (line?) instead of leaning way down to get to the damn lift pump lever.

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That is a great idea. I like the way you think.

One sneaky quick test is to get engine running, then turn off fuel supply valve on top of tank. Watch racor vac gauge, should go up rapidly since supply is off. Then open valve and gauge should drop to zero.

Watch bowl when valve is opened and see if there is a big burp of air coming through cyclone, if so you may have a vacuum leak.

If vac gauge does NOT show high vac with valve closed, then lift pump is probably weak.

Always keep a spare lift pump on the boat!! They poop often and randomly.

Several birds with one stone - I like that!

Greetings,
Mr. BS. Another variable in the equation... http://www.parker.com/literature/Racor/Mobile_Air_Separation_In_Diesel_Fuel.pdf

Nickair said:

That is a great idea. I like the way you think.

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(Referring to attaching the string to the primer lever, so you can actuate it when on the opposite side of the engine, where the injector pump is inconveniently located.)

And it works like a charm! Mine already had a small hole drilled in the end of the lever, so it was super simple. I just left it in place (stowed safely, of course), for next time.

RT Firefly said:

Greetings,
Mr. BS. Another variable in the equation... http://www.parker.com/literature/Racor/Mobile_Air_Separation_In_Diesel_Fuel.pdf

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RTF,

That all makes perfect sense (and it explains how the engine runs just fine once I manage to get it started, in spite of the fact that air is obviously entering the fuel system somewhere) - except that my other engine draws from exactly the same fuel tank, but doesn't suffer the same problem.

I'm definitely going to try the "shut off the fuel and watch the vacuum gauge" trick suggested by Ski, though. I obviously need to fix this problem, but I'd also love to know exactly what the problem is - and if I just replace / rebuild all the components, I'm almost certain I'll fix the problem, but won't know for sure what it was.

You state that both engines feed off one tank. That means the engine that is working feed is fine. Start there, where the hoses diverge to the filter. I have had Racors have the tops get un seated and not secure correctly (cocked a little bit) if the filter isn't fully down in the housing.

It sounds as if the filter is the air inlet. Make sure you change the little washer under the T handle. ( not just the rubber oring of the lid. ). Also, ensure the rubber gasket doesn't have a twist in it. BTDT!

Snug up on the hose clamps into the filter and to the common connection between the other engine feed line.

Greetings,
Mr. BS. Just another factoid provided by my offsite expert but something else you should be aware of and he and I agree you DO have other issues. MY money, as I've said too many times, is on that supply hose from the tank to the Racor. I've got a bunch of crow recipes standing by.

RT Firefly said:

Greetings,
Mr. BS. Just another factoid provided by my offsite expert but something else you should be aware of and he and I agree you DO have other issues. MY money, as I've said too many times, is on that supply hose from the tank to the Racor. I've got a bunch of crow recipes standing by.

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+1

One of the things that no one seems to have brought up on this thread is that Perkins engines have small rubber grommets in the fuel line connections.
For example, where the fuel lines enter/leave the fuel filter/injector pump/lift pump.
If you were to unscrew a pipe and withdraw it gently and look inside, you will see a black rubber grommet (like a small piece of black rubber pipe), you can withdraw this with a pair of small tweezers/fine long nosed pliers.
If this has been removed previously/ or is cracked/damaged in any way it's possible for a very fine amount of air to into the fuel system enter slowly and cause some surging, or if sufficient air enters, or throttle opened can stop the engine.
I hope you find this helpful.

Ski in NC said:

... Always keep a spare lift pump on the boat!! They poop often and randomly.

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I keep a cheap spare electric pump onboard with alligator clips and enough wire to run to the power bus.

Irish Rambler said:

One of the things that no one seems to have brought up on this thread is that Perkins engines have small rubber grommets in the fuel line connections.
For example, where the fuel lines enter/leave the fuel filter/injector pump/lift pump.
If you were to unscrew a pipe and withdraw it gently and look inside, you will see a black rubber grommet (like a small piece of black rubber pipe), you can withdraw this with a pair of small tweezers/fine long nosed pliers.
If this has been removed previously/ or is cracked/damaged in any way it's possible for a very fine amount of air to into the fuel system enter slowly and cause some surging, or if sufficient air enters, or throttle opened can stop the engine.
I hope you find this helpful.

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IR,

I've encountered this before on this engine, but since I'm getting air in the Racor, which is well below the lift pump, on-engine filter, injection pump and all associated metal piping, I don't think that's my problem.

RTF, I'm going to replace ONLY the fuel-tank-to-Racor line first, and try that. I've just GOT to know if you're right! <big smile!> If that keeps the air from building up inside the Racor - I'm still going to rebuild the Racor, because it's probably way past due for it. And I'll replace the Racor-to-lift pump line, because it's the same material and vintage as the tank-to-Racor line.

And then, because I've got nothing better to do (ha!), I'll duplicate all of this on the other engine - except for the lift pump, which is obviously much newer than the one on the problem engine.

But it'll be after Thanksgiving before I get to try any of this. I know, the suspense is going to be terrible!

Greetings,
Mr. BS. Good grief! I don't know if I can take all that pressure...



Have a happy thanksgiving in any case.

Take the lift pump apart and see what's up.

bayview said:

Take the lift pump apart and see what's up.

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I will definitely do that. But only after I've got the new one in place and working.

UPDATE: Problem seems to be solved. Unfortunately, I ended up doing two things at the same time, so I will probably never know which of the two it was. Worse than that, I've lost my opportunity to call RT Firefly "a craven, flap mouthed wagtail".

While I was waiting for a weekday (when the hydraulic shop would be open), I went ahead and rebuilt the Racor.* Then, I was going to be in the vicinity of the hydraulic shop before I was going to get back on the boat - so I got the new supply line. Replaced them both, spent a LOT of time getting everything bled**, and now it seems to be OK. Engine has started and run without a hitch several times in the 3 days since then.

I really wanted to cut the fuel line apart and inspect the inside of it - but I forgot to get it back from the hydraulic shop after they built my new one, and when I called them a few hours later, the trash man had come and taken it away. Daggone it!

I still have the new lift pump that I'd like to install, and then disassemble the old one. But the other couple who owns the boat with us are taking it on a several day voyage down the ICW just after Christmas, and I won't get a chance to wring out a new pump before then, if I put it on now. Should I just let sleeping dogs lie for now, and send the new pump with them, just in case? (What am I saying - of course that's what I should do. Just typing it out made the alternative seem kinda silly. I will, however, do the test with the vacuum gauge and the fuel cutoff, to see how much pull the lift pump is generating. If it's pretty low, I may risk the swap now.)

*The Racor rebuild was a simple - although messy - job. If yours is starting to accumulate some crud inside it, don't be afraid to tackle the job. Gunk Engine Degreaser (or equivalent) for cleaning all the parts, then hot soapy water for rinsing the Gunk off (except for parts that I couldn't then dry completely with compressed air), then hot clean water for rinsing the soapy water off, then dry everything with compressed air and clean cloth. Reassemble with a little motor oil on all the gaskets and o-rings - good as new!

**I learned a valuable lesson about bleeding the lines after a major "interruption" such as I did (replacing the Racor and the fuel supply line): be sure to bleed each of the injector lines at the injector. By bleeding only the fuel line at the injector pump, and the bleed screws on the pump itself, I was getting nowhere. Only when I "cracked" all of the injector lines and cranked the engine several times did I finally get all the air out of the system. Will the injectors not allow just air to pass through them into the cylinder? Is there something inside them that has to be forced open by fuel under pressure? (Again, as I type, that makes sense. If there wasn't, the fuel would just constantly dribble into the cylinders. Right?)

Thanks, as always, for everyone's input on this. It's been my biggest maintenance puzzler since we got the boat, and all the advice here helped a ton. TF is fantastic!

Greetings,
Mr. BS. Alas, an opportunity missed is an opportunity lost BUT the main thing is you seem to have solved your problem. Well done! IF, perish the thought, there are still ongoing problems, rest assured you can pretty much guarantee the cause will NOT be either the fuel lines or the Racor. Thanks for the report and don't worry, IF you wait long enough you can still mean mouth me. I am wrong on rare occasions or at least I'm not 100% right (don't go there people).

Yea... Bleeding those motors can be pretty fussy. When I re-did my fuel rig, I added a small ball valve to the output side of the Racor so I could completely remove it without losing prime to the motor. If you're careful, you can even change out the lift pump without needing to crack the injectors. That is the biggest PITA to me.

The reason you have to crack the injector lines is because air can be compressed, fuel can't.
As regards the lift pump, if it ain't broke don't fix it.
Mechanics make money repairing other peoples fixes.


It seems no one like's bleeding diesel engines, I explain in a previous post how to avoid it by fitting a modified filter head to accept a 'spin on' filter incorporating a button pump. You simply start the engine until warm, stop the engine, with a plastic bag below the old filter, remove it, fill the new filter full to the top with diesel, spin it on, clean any spills, start the engine on idle, push the button on the pump a few times until it's running smooth, Job done !

SPOKE TOO SOON!

Back on the boat today - wanted to see what the vacuum gauge on the Racor would do if I restricted flow to it (with the shut off valve at the tank), as a way to test the strength of the lift pump (as recommended in a previous post). Started the engine, and it ran for about 4 seconds, then died. Wouldn't restart. I didn't have time to mess with it today, so it's back to the boat tomorrow.

Oh, joy.

(Irish Rambler - sounds like a cool idea, but I don't have the physical space to do that. I can barely get the existing on-engine filter canister in and out of its space because of all the hard fuel lines and engine brackets that surround it.)

Switch the fuel supply lines and see if the problem follows the fuel supply. This will tell if the problem is fuel delivery or engine system fuel pump or injection pump

Greetings,
Mr. BS. Wagtail here. Apologies for the misdirection. Seems like the likely culprit is the fuel lift pump since you've virtually eliminated all else. If not, I'm at a total loss as to what the issue may be. We have Lehmans but the basic system is the same unless I'm missing something. Fuel in tank, pickup in tank, line to Racor, line to fuel lift pump, through lift pump to fuel injection pump, to injectors, to combustion chamber...
If air is still getting into the system, logic dictates that it is on the suction side of your lift pump. It is indeed a frustrating, head scratching conundrum...