6-71 Fuel Pump Problem

[Passages]

Passages got splashed today and I immediately set about coaxing the engines back to life.

Port engine would not fire. Spins freely but not even a hint of firing. Air-Seps are clean. Fuel Tank was at 1/8 but I added another 15 gallons of fresh stuff. Disconnected the primary filter output hose and put the end in a bucket of diesel. Disconnected the secondary "in" hose and directed that to a jar. Cranked the engine for (3) 5 second bursts. No fuel delivery.

Am I missing something - like air in the fuel line - or does it sound like I need to bite the bullet and replace the fuel pump?

 

[Genesis]

Not yet.

Its possible that the system drained back during storage.

Check the secondary filter cannister. Drop the element and see if its dry. If it is, snug it back up and crank again a few times, see if the level is coming up.

Also check the check valve that should be in the line and make sure you didn't pick up a slug of crud in there that's plugging it up.

 

[Cobra29]

Had a similar problem after changing Racor's. When opening the check valve back up, it was maybe 4 degrees off of being in line. Enough to stop fuel flow on my boat. After an hour of tearing everything apart, I noticed that, moved the check valve so that it was exactly in line and everything started and ran fine. Stupid, I know but I hope that is the dumbest thing I ever do. Difference was that my engine ran for about 5 minutes before shutting off.

 

[Pascal]

i've had a similar and intermitent issues on the stbd engine (8V71) once in a while it won't fire or it will fire, stop after 10 or 15 seconds and not restart.

I have to insert a hand pump at the primary outlet and re prime the system by forcing some fuel thru the secondary and to the pump. I quicly reconnect the line and it fires right up.

it's one of these pesky glitch which don't happen often enough to make it worth tearing everything up but i will eventually have to fix it...

it seems to happen mostly when the tank is under 1/3 full so I'm guessing it must be sucking a little bit of air somewhere. Next time, I'll flip the fuel valve when it happens to see if' it's a plumbing issue between the tank and fuel mainifold or between the manifold and fuel pump...

 

[Freestyle]

I lost fuel to an engine underway and called my mechanic. Here is what he told me to do and it worked.

First the pump is a gear type pump that can self prime. So he had me take a bottle of WD-40, spray it into the air filter while cranking. The boat started by butning the WD-40. With the engine running the fuel pump primed itself and all went well.

Although it worked, I am sure this idea will get some criticism from the big brains of the site because it just felt stupid spraying WD 40 into an engine. Safer than ether though.

Bruce

 

[Scott Mather]

On Our 6-71's I have run the engine out of fuel a couple of times.

You just have to manually fill the main filter on the motor and the secondary
Racor's. The motor has always fired right up after this.

 

[Nonchalant1]

First take off your sedondary fuel filter (on the engine), pour it full of fuel, and put it back on. Then, do you have a manual fuel priming pump? My boat has a little manual fuel priming pump. It's a very small simple pump connected right in the fuel line between the fuel tank supply hose and the RACORs, with a black knob on the top, used when you change RACORs. I pump up fuel with it to refill the RACOR, then put the top on the RACOR tight and turn OFF the fuel supply valve to the tank and then pump some more. This pumps fuel towards the engine, including filling the Flo-Scan cannisters if they have air pockets. Works for 8V71s.

Doug Shuman

 

[Passages]

Thought I'd give everyone a follow up. As suggested, I topped off all the fuel canisters with fresh Diesel. No luck.

I then ran off to our local DD dealer for a $90 rebuilt fuel pump. Actually twice - (NOTE THAT THE PORT ENGINE NEEDS A RIGHT HAND ROTATION FUEL PUMP) Installed pump and Still no luck.

As a sense of desperate panic set in I went to seek out the advice of the yard mechanic. He shrugged it off saying " i kin get er started in 10 seconds." He proceeds to pull out a can of ether but at this point, I'll try anything. Sprays the air filter and the engine came to life immediately.

I now wonder if I should have started with ether (or WD-40 according to Freestyle) and avoided 2 trips to the Detroit dealer. Live & Learn.

 

[first230sl]

So I take it that the issue was indeed a priming issue - and running it on ether kept the pumps going long enough and fast enough to get the fuel properly up to the injectors?

Just want to be sure I understand.

Thanks

Thought I'd give everyone a follow up. As suggested, I topped off all the fuel canisters with fresh Diesel. No luck.

I then ran off to our local DD dealer for a $90 rebuilt fuel pump. Actually twice - (NOTE THAT THE PORT ENGINE NEEDS A RIGHT HAND ROTATION FUEL PUMP) Installed pump and Still no luck.

As a sense of desperate panic set in I went to seek out the advice of the yard mechanic. He shrugged it off saying " i kin get er started in 10 seconds." He proceeds to pull out a can of ether but at this point, I'll try anything. Sprays the air filter and the engine came to life immediately.

I now wonder if I should have started with ether (or WD-40 according to Freestyle) and avoided 2 trips to the Detroit dealer. Live & Learn.

 

[Passages]

Yep, cranking the engine only got the the RPM's to about 2-300 according to my tach. With ether, it bumped it up to about 600 for a few seconds which was enough to bleed the air and get the fuel flowing.

Question to Group - What's the real deal with ether? I have never used it before but have heard elsewhere that it should not be used because of possible engine damage. A properly tuned engine should never need it. The yard mechanic says he uses it all the time (on cranes & yard equiment) In my case, it was just what I needed. Should a can be kept on board just in case?

 

[ADaily3224]

A much safer way to start a "DRY" engine is to put some diesel in a plastic spray bottle, like an old windex bottle. Have someone turn the engine and hit the intake with a few pumps, it will fire. Tony D

 

[Genesis]

NO!

Ether is extremely dangerous. It can detonate while the piston is on the way up, and if it does, the result can be holes in the pistons or rods through the block.

WD40 used to be mostly kerosene. It was "safer' than Ether, but still not safe. I believe the formula has changed however, and it may not work well anymore.

I've never seen a Detroit I couldn't re-prime without using a starting assist, assuming the check valve on the inlet side of the fuel system is there and WORKING. If its not then its entirely possible to be unable to pull fuel successfully from the tank.

 

[Pascal]

passages,

fillin the filters never helped when that happens to me, it takes a little extra pressure from a hand pump to force some fuel into the lines and up to the pump. I understand you can't really push fuel past the pump but the pressure helps in my case.

 

[Genesis]

I do not put anything into the intake other than AIR!

If your fuel system will not re-prime without all this garbage going on fix the problem instead of applying band-aids. If the correct solution for your configuration is an electric priming/boost pump, install one. A Walbro is about $100 from Depco and that plus a check valve will do it.

Unless someone has radically screwed with the original configuration on these boats there simply shouldn't be a problem. I've seen some Berties screwed up so bad that they would NOT reprime unless the tanks were full to the vents, but never on a Hatt. At least not yet.....

The fuel pump on the engine is a gear pump and is positive-displacement. It WILL pull air through and re-prime UNLESS you have an air leak in the system somewhere or its relief valve is stuck or has something in it preventing it from closing correctly. If you have either problem find and FIX IT. If you need to pressurize the "suction side" with the engine off to find the leaks, do so. Those leaks are hurting your performance SEVERELY, because any air in the fuel compresses and causes improper injection.

Detroits require proper fuel pressure in the rail to run right, and they, like every other diesel, require clean fuel with no entrained air bubbles.

The filter most people forget is the one on the engine - on the PRESSURE side of the pump. That has to fill before the engine will start. Problem is that while the pump will do it, at cranking speeds it takes a LOOONG time. So drop that cartridge housing and fill it with Diesel Kleen (or fuel) - just make sure you don't cross-contaminate the output side, because that is your "last chance" filter before the gunk gets to your injectors and fouls them!

 

[wshelton]

I have DD671s and watched my mechanic prime my engine one time after changing the fuel filters. He used a can of starting fluid sprayiing it into the air filter as I cranked the engine. He massaged the sraying enough to run the engine long enough to prime itself and all was well. I used this method later too, this time I ran out of fuel. On thing though. It takes two people. One to hold the start button on the engine while the other guy is spraying the starter fluid. Glad I had seen this done before. I ran out of fuel on the Ohio River. Fortunaley I had the use of the other tank to draw from after geitting restated... Also the other guy, my son.

 

[Genesis]

I'll show you guys the correct solution to this problem tonight. I've got pictures of my new fuel filtration/priming system, right next to the 'old technology' one it replaces (only have one side done thus far)

Never will I again have to worry about anything silly like this, and I get polishing out of it "for free" too.

 

[Genesis]

As promised...

From right to left....

(not visible - Fuel shutoff), Fuel inlet, strainer (30mic relative, plus water-block), filter (10mic "stratapore", rated for the new common-rail engines like the QSM-11s - radically more than you need for Detroits but overkill is good), output shutoff (to isolate for filter changes), then suction for the Walbro, a check valve, pressure on the Walbro, vacuum gauge (not visible in the first picture but is in the second), then diverter valve back to the return line. Both the strainer and filter elements have water drains at the bottom (finger-operable; no wrench required)

The check valve in the line to the engine's fuel pump has been REMOVED. It was a 1/4" bore thing - Detroit original - but that HAD to be restricting flow at higher output.

The wiring to the pump is temporary (I had to run jumpers there to prime the system so I could start up after installing it, and of course to test for leaks); that will be replaced by a spring-wound timer in a utility box on the forward firewall.

Now, the idea is this:

1. The Walbro makes it trivial to reprime the engine. Turn it on, it sucks fuel through the filters. To prime you OPEN the diverter valve (to return) and energize the pump until it stops cavitating. Now close the diverter. The pump will go into "tick-over" mode as it reaches its rated pressure (4 psi). When you hit the starter you now are FORCING fuel into the pump, bypassing any air that's in there immediately. On a completely dry start (which the first one was after installing this) I got instant light-off. If the pump is left running there's no foul, since the check valve allows full flow through to bypass the pump if necessary.

2. To polish the fuel tank, you open the bypass and energize the pump. The pump is continuous duty rated, so it can be run for a long time. It will turn over my tank (300 gals each side) in about an hour and a half; figuring you need 10 "turns" to insure you filter it all, overnight will just about do the job.

3. To TRANSFER fuel, you set the suction and return selectors in the lazarette as desired, open the bypass, and energize the pump. Voila. Be careful - you can overfill a tank this way REAL easily! However, this allows you to easily transfer fuel if required as well.

Oh, by the way, note the size difference between the two systems - the new one and the old dual-RACOR (redundant.) Which would YOU rather have in your engine room? Never mind that there's no more taking the RACORs apart and cleaning them, plus changing that damn bottom seal (the one you might not even know is there between the tube and baseplate - its a real pain to both get apart and reassemble.) With the priming pump I can replace a pair of clogged filters within minutes if necessary and re-prime the system, so there's no real need for the "instant swap" capability of the RACOR setup. Plus the vacuum gauge is "in your face" from the top of the engine room hatch.

Sorry about the very visible mess - I took these this evening and I'm not quite done, as I have to put in the timer box and of course do the other side.

Something to think about.... this wasn't terribly expensive to put together either....

 

[HATT 46]

Passagess, thanks for(correctly) pointing out the fuel pump rotation issue. I installed the wrong fuel pump, the one marked "R", on the stb. engine and it worked only when I reversed the "IN" "OUT fuel hoses. Any thoughts?

 

[Genesis]

Don't do that.

The pressure regulating valve won't work right with the pump reversed.

 

[Traveler 45C]

I suppose in an emergency, priming the engine with starter fluid will be quicker. But, you may experience engine damage and DD specifically says don’t do it.As Genesis pointed out, the starting fluid may detonate as the pistons are on their way up. Not good! Or, the fluid may cause Air Box deposits to break loose and be ingested by the engine cylinders. Really not good!!!

I also had a difficult time trying to start the engine after a filter clogged. I had to refill all filters, crank the engine (2 or 3 sets of 10 secs). Refill the filters and then another round of cranking. This I had to do a few times until the engine finally primed itself. Too much time, mess and cranking for me, especially in heavy seas!!!

Genesis, I like your set up. Smart, logical and efficient. It solves many issues while adding benefits. You really need to write a book!

Now I’ve got more items on my “To do” List… I’ll put another 6 pack in the fridge for you.