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That had to hurt him a bit! Well, the lesson is to not remove the injectors and try to run them on the engine I guess...but who would do that anyway? The question as to the spray from the injectors being at a level that could hurt your fingers seems to hinge on the point that you will not be exposed to the injector output at all..it is still buried in the engine. The fuel being delivered to the injector tip is in a far larger hose, and under far less pressure than the flow at the tip of the injector. Also, if you are careful, you will not even get any fuel on you when you do this. (I have to do it this weekend in fact..still have a bubble of air in one injector line which causes that cylinder to fire and run a bit after the other cylinder does. They eventually both get going ok.. but I like to have the engine start on the first compression stroke..in case the battery ever gets so weak that all it has left is the energy to rotate the engine one time. It's cheap insurance).
Larry DeMers
s/v DeLaMer
Cape Dory 30
Olli Wendelin wrote: I have heard of this type of injury happening in a diesel shop while rebuilding fuel injectors. While testing injectors someone would get there hand in the way of the spray from the injector.
My YSB12 engine is not self bleeding. I must crack open the nut on the high pressure line at the injector to bleed the line. I agree that this will not create this type of spray when the nut is cracked open prior to cranking the engine.
I did see this type of injury once. A buddy was cutting concrete on a dock piling (underwater) and passed his finger in front of the hydroblaster. This is 18000 psi max but I think they were running at half that. It cut to the bone and injected river water. He ended up in the hospital for a week. The biggest problem ended up being infection.
Take a look at the "crush" washer on the fuel filter. Is it really a solid copper washer that maybe has been chewed up a little from reuse??? Be careful of the bolt there, if it is hollow (threaded portion is drilled out) as they WILL break if overtighted. If still having problems, look at all connections, hoses, fittings before the engine filter where you are seeing air when bleeding. Does your Racor have a bleeding pump on it that needs to be locked down so as not to leak (draw air)??? The high pressure side (past the injector pump) should mostly self bleed, as you are pushing fuel/air to the injectors. The problems are the pumps which, depending on design, cannot usually pump air, hence airlock. The pressure to the injectors are up in the thousand(s) range (again depending on engine and usage), and if there is pressure when you crack an injector fitting, the fuel through that initial tiny opening, could suprise you in the hand OR FACE. The big safety concern is the bench testin gof the injectors, filled w/ fluid and pumped up to just shy of openning pressure. There is no high tech stuff here, so go thru the low pressure side, in a logical manner and the leak will be found!!
A few comments have been posted on the low pressure side being a potential problem. OK - but the question I have is this - if the leak is somewhere on the low pressure side, why would the engine keep running once it starts? It ran for 3+ hours at 2000 RPM after we got it running the other day. Wouldn't a leak in the low pressure side allow air in by suction and cause the engine to quit? I was more inclined to think of a leak past the lift pump that allowed air back in after the engine shut down and "depressurized", perhaps through the washer on the bleed screw, (which may be the wrong size). I am picking up some of the correct washers and an OEM filter tomorrow from the Volvo dealer. Will work on her this weekend and hopefully report success to you guys next week. Thanks for all the info. PS - If the thing was running on only one cylinder, would it be VERY obvious? It sounds smooth (at least as smooth as a diesel should I think) but it has always sounded that way. When I tried to bleed it before at the injectors, I never had any fuel from the fron cylinder, but when it started, it seemed to run just like it always had. I guess that this time, I will crack the nut on the injector when it's running and see if there is any performance degradation.
Also - If Larry DeMers happens to read this - I think you mentioned the return check balls getting easily gummed up. Is this "user servicable" or is it another Y2K issue (yet another 2 grand) to scope out. Thanks.
Saying the suction side (pre lift pump). Half way thru the lift pump, it goes from suction, to low presure (and a good amount of volume). From there, it is low pressure until most of the way thru the injector pump, which precisely metered and timed very high pressure (but very low volume). When you have problmes, could you be moving things and causing a suction leak to reseal it self??? I take it the fuel flow is from teh tank, thru the new Racor, thru the lift pump, thru the Volvo filter, to the injector pump. Take a close look at the "new" Racor. Any plastic to have a hairline crack, the o-rings not chewed up, the pipe fittings attached w/ pipe sealant (dope or tape), the fuel hose clamps to them tight (good hose too)??? Look at the fuel line connections at the fuel tank, that were moved around to up the Racor on. Anything from the tank to half way thru the lift pump is suspect. After the lift pump should be show as a leak (and possibly reduced top end rpm). Remember, a diesel controls fuel only, it can have as much air as it wants.
Note: Dont go wild w/ teh thread sealant on any pipe fittings. pieces or globs can clog other things down the line (filters, etc).
Sorry about the comment on the copper washer being chewed. Forgot which filter would be where and got the Racor and primary reversed.
Thanks Mark I'll check this over very carefully. The Volvo guy said to see if there are any bubbles in the Recor right at engine shutdown, so I'll look there too. I'll also check the fuel line connections to make sure they are tight. Hope to have some answer by Monday.
John
Mark Yashinsky wrote: Saying the suction side (pre lift pump). Half way thru the lift pump, it goes from suction, to low presure (and a good amount of volume). From there, it is low pressure until most of the way thru the injector pump, which precisely metered and timed very high pressure (but very low volume). When you have problmes, could you be moving things and causing a suction leak to reseal it self??? I take it the fuel flow is from teh tank, thru the new Racor, thru the lift pump, thru the Volvo filter, to the injector pump. Take a close look at the "new" Racor. Any plastic to have a hairline crack, the o-rings not chewed up, the pipe fittings attached w/ pipe sealant (dope or tape), the fuel hose clamps to them tight (good hose too)??? Look at the fuel line connections at the fuel tank, that were moved around to up the Racor on. Anything from the tank to half way thru the lift pump is suspect. After the lift pump should be show as a leak (and possibly reduced top end rpm). Remember, a diesel controls fuel only, it can have as much air as it wants.
Note: Dont go wild w/ teh thread sealant on any pipe fittings. pieces or globs can clog other things down the line (filters, etc).
Sorry about the comment on the copper washer being chewed. Forgot which filter would be where and got the Racor and primary reversed.
John Dupras wrote: A few comments have been posted on the low pressure side being a potential problem. OK - but the question I have is this - if the leak is somewhere on the low pressure side, why would the engine keep running once it starts? It ran for 3+ hours at 2000 RPM after we got it running the other day. Wouldn't a leak in the low pressure side allow air in by suction and cause the engine to quit? I was more inclined to think of a leak past the lift pump that allowed air back in after the engine shut down and "depressurized", perhaps through the washer on the bleed screw, (which may be the wrong size). I am picking up some of the correct washers and an OEM filter tomorrow from the Volvo dealer. Will work on her this weekend and hopefully report success to you guys next week. Thanks for all the info. PS - If the thing was running on only one cylinder, would it be VERY obvious? It sounds smooth (at least as smooth as a diesel should I think) but it has always sounded that way. When I tried to bleed it before at the injectors, I never had any fuel from the fron cylinder, but when it started, it seemed to run just like it always had. I guess that this time, I will crack the nut on the injector when it's running and see if there is any performance degradation.
Also - If Larry DeMers happens to read this - I think you mentioned the return check balls getting easily gummed up. Is this "user servicable" or is it another Y2K issue (yet another 2 grand) to scope out. Thanks.
John Dupras
s/v Mariah
John, when I was having problems with my md7a fuel system the engine would start and run fine, the problem being I couldn"t get it started again after shutting it down. the problems were, 1. compromised fuel line, this was discovered by using a vacuum gauge on line. 2. the fuel line looped up above fuel tank then dropped down to fitting on tank creating a air lock in line and a bear to bleed out. this was fixed by shortening line to run directly into fitting then down to engine. (all downhill) all fittings were cleaned and teflon tape used when re set. 3. the fuel pump itself was malfunctioning. pulled and replaced. also, the hand pump on fuel pump can be really slow moving fuel/air through lines. I used the vacuum gauge to bleed up to fuel pump. the primer bulbs for an outboards external tank works great as well moves a lot of fuel quickly. If you don't have an inline fuel shut off valve just upstream from racor, they work well stopping air from running up fuel line to tank. good luck Ben